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JeepsAndGuns
10-02-2011, 07:49 PM
Well, yesterday I finally got brave enough to try the 7427 pcm. I wasnt brave enough to jump in feet first and go all out. So I spent a couple hours and built a adapter from the plug from a junk 7747 ecm and some spare pigtails from a 7427. That way if it ran bad, or needed lots of tuning, I could simply unplug it and plug back in my old 7747 and drive it when I needed.
First lesson learned, dont get in a rush and install the eeprom in backwards! :laugh: I bought the moates G1 adapter, and I was so used to pin 1 being at the handle end of my zif socket like I have on my 7747, I just threw it in the same way. Turns out, pin 1 goes in away from the handle on the G1.
After I turned on the key, and the fuel pump never shut off, and I couldnt get aldl connection, I figured out the problem. I dont know if I corrupted the bin on the chip, but I didnt want to risk it. So I threw it back in the autoprom, erased it then re programmed it. I installed it and it works fine, so I didnt fry the eeprom.
Started the datalog and went for a small test drive.
After the drive, my first impression is wow. What a vast improvement. It idles smoother and better, acceration is smoother and more crisp, steady cruise is smoother, throttle response is better, and even decel is smoother and better. Light accel is better/smoother, wot accel is better/smoother. Even seems to have just a tiny bit more power. Seems pretty much all rpm ranges are better.
All this from a mildly modded stock bin. I imported my timing table from my old 7747 tune, and then just did some smoothing of the fuel maps. I also followed the steps and disabled all the trans controlls and turned off all the trans trouble codes, also disabled egr and turned off that code.
Going by the datalog, seems all cells from about map 50-20 I was rich, map 60-80 were pretty close, and map 90-100 was a touch lean. So just a few logs and tuning and I think it will be all set.

Now for the one and only problem I am having---the knock sensor. I made a small jumper wire to go in the plug for the esc to connect the knock sensor to the correct input on the pcm (using the old esc signal wire) but I am getting the knock sensor or circuit error code. So the check engine light is staying on. Its the only error code I get.
I looked up on advance autos website and looked up a 89 and a 95 chevy 1500. The knock sensor I am using is for the 89 350. When I look up the 95 1500 truck, it shows two knock sensors. One for a auto, one for a manual trans. The one it lists for the manual trans is the same part number of the one it lists for the 89 truck. The memcal I am using is of corse from a auto truck. So do I need to use the knock sensor it lists for the auto trans models? I'm thinking mabey the esc in the memcal is not seeing the knock sensor I am currently using.

EagleMark
10-02-2011, 09:49 PM
Subscribed since I am putting together a 427 for my sons IH Manual trans...

dave w
10-02-2011, 11:16 PM
The knock sensor I use when I convert to a '427 is a Standard Ignition KS6. The KS6 measures about 4K ohms. Most likely the knock sensor your currently using is 100K ohms? Try installing a 4K resistor instead of the current knock sensor and see if the error goes away.

Maybe you need to bypass the old ESC module mounted near the EGR valve?

dave w

JeepsAndGuns
10-03-2011, 02:59 AM
I have a custom install on a non chevy engine, no egr and the esc is on the firewall in my setup. But I unplugged it and installed a jumper wire between the pins in the plug to connect the knock sensor to the pcm. I will try a resistor like you mention, is it something common I can find at somewhere like radio shack? Do I just put it inline somewhere between the knock sensor and the pcm?

I had a code pop up today while doing another datalog. I dont know/cant remember if it was there yesterday or not. But on the error code list in the datalog, I am getting a error next to 36 throttle kicker failure. What does that mean? I remember seeing paramiters in the bin about throttle kicker settings, but didnt really pay attention to them.

EagleMark
10-03-2011, 07:49 AM
Yes radio shack will have them, may need a couple depending on what sizes they have. Wire them in series (in line) to make 4K. Not parrellel (next to each other). I bought a BIG pack that has 100s of them for $5. and built VATS bypass plugs.

Your overall first impression has got me excited to get the kids truck done! :thumbsup:

Six_Shooter
10-03-2011, 08:05 AM
Yes radio shack will have them, may need a couple depending on what sizes they have. Wire them in series (in line) to make 4K. Not parrellel (next to each other). I bought a BIG pack that has 100s of them for $5. and built VATS bypass plugs.

Your overall first impression has got me excited to get the kids truck done! :thumbsup:

I have to ask why wouldn't you use a parallel configuration to attain a 4K ohm resistance?

The 4K resistance would be to ground with the knock sensor unplugged. This is just for testing, not a permanent solution.

gregs78cam
10-03-2011, 08:07 AM
From what I have read, the auto trans vehicles were the first to use the '6395, '7427 PCMs due to E-trans control. The manual trans still used the '7747 for a few years. The '7427, 6395, and others use a different Knock sensor and the circuitry for that knock sensor is on the memcal, so there is no need for the separate ESC. I thought there was a way to use the old KS with the '7427 but i don't recall exactly how. The info is out there, you might search TGO in the TBI board. So yes easy way is to use the right KS for the Auto.

EagleMark
10-03-2011, 01:39 PM
Yes radio shack will have them, may need a couple depending on what sizes they have. Wire them in series (in line) to make 4K. Not parrellel (next to each other). I bought a BIG pack that has 100s of them for $5. and built VATS bypass plugs.

Your overall first impression has got me excited to get the kids truck done! :thumbsup:

I have to ask why wouldn't you use a parallel configuration to attain a 4K ohm resistance?

The 4K resistance would be to ground with the knock sensor unplugged. This is just for testing, not a permanent solution.
Electricity takes the path of least resistence, ie it would all go through one resister in parellel. Next time you have resisters out try it. 1k and 1k in series is 2k. 1k and 1k in parellel is 1k.

Six_Shooter
10-03-2011, 07:24 PM
Yes radio shack will have them, may need a couple depending on what sizes they have. Wire them in series (in line) to make 4K. Not parrellel (next to each other). I bought a BIG pack that has 100s of them for $5. and built VATS bypass plugs.

Your overall first impression has got me excited to get the kids truck done! :thumbsup:

I have to ask why wouldn't you use a parallel configuration to attain a 4K ohm resistance?

The 4K resistance would be to ground with the knock sensor unplugged. This is just for testing, not a permanent solution.
Electricity takes the path of least resistence, ie it would all go through one resister in parellel. Next time you have resisters out try it. 1k and 1k in series is 2k. 1k and 1k in parellel is 1k.

You would think so, but that's not entirely the case in an instance like this. ;)

Trust me, I've worked with resistors for many years. Some of the circuits I needed to trigger had an allowable tolerance of 10 ohms, and required some creative resistor combinations to get it sometimes.

If you'd have seen some of the calculations I had to go through during my Automotive Electronic Accessory Tech training, it would blow you away. The sad part is I don't quite remember how to use Kirchoff's Voltage Law anymore. I need to go through that again.

On the other hand, if you use two resistors of the same value in parallel the final resistance will always be half the original value. So there's no reason to never use resistors in parallel.

EagleMark
10-03-2011, 09:35 PM
Great! Now that I had it straight in my head it may not be the case always... :mad1:

I had followed on online write up to make a vats bypass and they showed and said it was OK to parallel and even showed a picture. So I added up 2 resistors parallel and FAIL! Measured them and it came out to the one resister. I then got 2 new resisters that added up to exact ohms needed in series and it was still the same amount.

JeepsAndGuns
10-04-2011, 02:29 AM
The 4K resistance would be to ground with the knock sensor unplugged. This is just for testing, not a permanent solution.

Oh, I was thinking yall ment to put the resister between the pcm and my current knock sensor to make it work. I would rather just install the correct sensor.
So with the parts stores showing two of them, one for auto, one for manual, with the manual one being the same part number as the one I am currently using, would I be correct in assuming I need the one they list for automatic?

Also, what about this throttle kicker error code I am getting? I cant seem to find any info on it online :confused:

dave w
10-04-2011, 03:25 AM
I use the Standard Ignition KS6 for an automatic transmission when doing the '427 PCM conversion. The parts stores are not able to look up the correct knock sensor after the '427 PCM conversion. The old ESC module needs to be completely removed from the old knock sensor circuit.

There are four wires that go to the old ESC module:
1. 12 volt with ignition switch in the on position. (Usually Pink wire with a Black Stripe)
2. Ground. (Usually a Black wire with a White Stripe)
3. Knock Sensor wire ~ from knock sensor to ESC Module. (color varies by model year)
4. Knock Sensor wire ~ from ECM to ESC Module. (color varies by year)

Solder together wires 3 and 4, and check with an ohm meter to make sure you have continuity from the ECM to the Knock Sensor.

dave w

EagleMark
10-04-2011, 04:15 AM
I use the Standard Ignition KS6 for an automatic transmission when doing the '427 PCM conversion. The parts stores are not able to look up the correct knock sensor after the '427 PCM conversion. The old ESC module needs to be completely removed from the old knock sensor circuit.

There are four wires that go to the old ESC module:
1. 12 volt with ignition switch in the on position. (Usually Pink wire with a Black Stripe)
2. Ground. (Usually a Black wire with a White Stripe)
3. Knock Sensor wire ~ from knock sensor to ESC Module. (color varies by model year)
4. Knock Sensor wire ~ from ECM to ESC Module. (color varies by year)

Solder together wires 3 and 4, and check with an ohm meter to make sure you have continuity from the ECM to the Knock Sensor.

dave w
That sir is excellent information that should be in your 427 conversion article! :wtg:

Maybe it is but I don't remember it...

JeepsAndGuns
10-06-2011, 02:40 AM
Yes, the old esc will be completely removed from the system once I get some time. I plan on doing that when I do the ecm plug swap and get rid of my adapter harness I am using right now.
The local parts stores done have that brand of knock sensor, is there a way to cross refrence that to another brand? The monkey behind the parts counter had no luck doing so.


I did some google work on this throttle kicker failure code I am getting, and I had zero luck on finding anything. All I can find when I search throttle kicker is a bunch of stuff about carbs, when I search error code 36 I get a bunch of other error codes. And I see no pins labeled for a throttle kicker on the wiring diagrams. So for now I just turned off the error code so it doesnt come back on. :confused:

Six_Shooter
10-06-2011, 03:19 AM
What makes you think it's a "throttle kicker" error?

The most likely error is "4T60-E Shifting Error" which would be reflective of the code you're running.

EagleMark
10-06-2011, 04:33 AM
What's a thottle kicker?

there's a varity of codes depending on vin "?" here's one for a 92 93 chevy 5.7L Vin J
36 ECM detected less than 60 high resolution timing pulses between each low resolution pulse for 5 consecutive cycles.

other 36 codes could be MAF or DIS on a quad 4 engine.

What was your PCM out of?

dave w
10-06-2011, 07:10 AM
Yes, the old esc will be completely removed from the system once I get some time. I plan on doing that when I do the ecm plug swap and get rid of my adapter harness I am using right now.
The local parts stores done have that brand of knock sensor, is there a way to cross refrence that to another brand? The monkey behind the parts counter had no luck doing so.

Maybe this information will help? Bring an Ohm meter to make sure the knock sensor is 4K.

dave w

JeepsAndGuns
10-07-2011, 02:38 AM
What's a thottle kicker?

there's a varity of codes depending on vin "?" here's one for a 92 93 chevy 5.7L Vin J
36 ECM detected less than 60 high resolution timing pulses between each low resolution pulse for 5 consecutive cycles.

other 36 codes could be MAF or DIS on a quad 4 engine.

What was your PCM out of?


The PCM itself is from a 95 half ton truck, 350 automatic. BCC, BJYK was the chip that was in it. Right now I am using the moates G1 adapter and running a 27SF512 chip. The bin I am using is one posted up here on my last post. BMHK, witch is supposed to be for a 454 with a manual trans. It of corse uses the 0E (tunerpro V5) defination. I am also using the (tp V5) 0E datastream defination for the datalogging. Its what labels the code 36 as "throttle kicker failure" Also when looking through the bin, there are paramiters for the "throttle kicker" So, did some trucks actually use a "throttle kicker"? From what I have seen online, a throttle kicker is simply a solenoid or stepper motor that pushes aganst the throttle to open it slightly, in order to raise the idle.
It seems to run fine, well better than fine, like mentioned at the start, it runs way better than it did with the 7747, so I'm not really wanting to think its those other trouble codes (I saw those too when searching)

EagleMark
10-07-2011, 02:43 AM
I don't know the answers, but I'll bet the throttle kicker has something to do with the manual trans and shifting, so between shifts the engine does not go back to idle, cleaning up emmisions and making shifting easier.

EDIT: Found three for 1995

DTC - 36 MAF sensor error

DTC - 36 24x Crankshaft position sensor circuit error

DTC - 36 4T60-E Shifting Error

Full list found here:
viewtopic.php?f=9&t=311 (http://www.eagle-mark.com/Forums/viewtopic.php?f=9&t=311)

JeepsAndGuns
10-08-2011, 02:54 AM
Yea I found those same codes with google, they didnt really seem to fit since I dont have a maf sensor, or a 24x crank wheel. But whats that 4T60-E shifting error? Something to do with the auto trans?
I looked last night, and both tuner pro version 5 0E and 0D definations and adx files say 36 is throttle kicker failure. And both have paramiters in the bin for a throttle kicker. So is it possiable they have been miss labeled by the person who made the definations?

I even went as far as calling the local chevy dealer and asked parts if there was a throttle kicker on any of the 95 model trucks. He had never even heard of a throttle kicker, and could find nothing of the sorts in his parts program. I then talked to one of the shop techs and he seemed to think mabey it was used on like the kodiak HD trucks that had a pto, as a way to run the engine at fast idle. I transfered back over to parts cause he said he could look up the BCC. All he could pull up was that it was a 5 speed bin, but had no info on what that BCC was originally supposed to be for. (this is the BMHK bcc, just fyi)
One thing I might try, is to load up the BJYK bin (350 auto) that I made up and see if the code sets when driving with that bin. Just depends if I have time this weekend.

JeepsAndGuns
10-10-2011, 03:09 AM
Well I think I have figured out this throttle kicker issue, well sort of, if we really want to call it a issue.
I have noticed the last few times I have drove it, it wanted to stumble, kinda almost stall as I was pulling out from a dead stop. This was only while letting out on the clutch to pull out, if it was a rolling start, it wouldnt do it. I had to give it more throttle to pull out than I should. I thought this was odd as it didnt do it the first few times I drove it, even more so odd as the first few times I drove it, it actually pulled out better than it did with the old 7747. The issue seemed to appear as I was tuning my fuel maps. I was starting to think there was some issue with either fuel or spark starting to show itself.
As I was driving back home from a friends house, it hit me :idea: . Back when I first started getting that error code, I noticed once or twice, the code for iac failure was on too. I thought that was very odd, as the iac was working perfectly fine. So I just ignored that code. When it hit me, I realaized the pulling out issue started about the same time I turned off the error code for the throttle kicker failure. But thinking it was a external bolt on part that was not being used (like the egr valve), I went to paramiters for the throttle kicker and set the enable temp to max so it would never turn on (just lke I did the egr) And then turned off the error code for it.
So I figured, mabey this had something do do with the pulling out issue. So I went back into the bin, and set the enable temp back to what it was stock. I then test drove and the pulling out issue is gone. I watched my datalog dash while pulling out, and when you do so, it must sense from the engine load increasing and rpm dropping slightly, that you are trying to pull out, cause when I am pulling out, it openes the iac up a significant ammount, I guess thats the "kick" It opens it up to give you more throttle and air to give it a extra kittle kick when pulling out.

Only one last issue, I am still getting that iac failure error code. The check engine light is not on, but the error code is showing on the error code list in the data log. I find this very odd, as the iac is working perfectly fine. Could the error code simply be stored in the memory, and just show up now every time I drive it? I hear that you have to have these un plugged from power for several days to clear the memory, is that true? I went ahead and unplugged it and I am leaving it unplugged untill next weekend when I get some more time to do some more tuning.

dave w
10-10-2011, 04:43 AM
Well I think I have figured out this throttle kicker issue, well sort of, if we really want to call it a issue.
Only one last issue, I am still getting that iac failure error code. The check engine light is not on, but the error code is showing on the error code list in the data log. I find this very odd, as the iac is working perfectly fine. Could the error code simply be stored in the memory, and just show up now every time I drive it? I hear that you have to have these un plugged from power for several days to clear the memory, is that true? I went ahead and unplugged it and I am leaving it unplugged untill next weekend when I get some more time to do some more tuning.

I usually need to adjust the IAC / Throttle minimum air to about 10 ~ 15 steps with the engine fully warmed up and parked in neutral. There are several methods to adjust the minimum air. My minimum air adjustment method is NOT the conventional method. I simply adjust the throttle stop screw, while watching the data log, with the engine running, fully warmed up and parked in neutral.

The memory will clear after 30 seconds or less after disconnecting the power from the PCM.

EagleMark
10-10-2011, 09:05 PM
I do what dave w does, but when done TPS voltage should be under 1.0 volt. Optimum is .54. but told from pioneers on Thirdgen anything under 1.0 volt is fine.

What JeepsandGuns is saying about throttle kicker has been my suspicion the entire time that there is more in the chip different for manual than just turning off the auto trans. I was told this by a Detroit EFI engineer to always start with a manual bin for manual trans as there is differences in chip. But not apparent in anyones hacks, that I have seen so far.

Since there are 100 things in IAC logic it would be plausible. Since we know even before EFI that contraptions were made to slow throttle to idle when shifting on carburetors cars for EPA/Emissions reasons it would be silly to think they are not in EFI programming.

EDIT: Yes the error code will be stored even after the problem is fixed. There is a paremeter that clears error codes after so many starts and not receiving an error. Just disconect PCM or batterey, I always give one minute, I do not know actual time needed, but one minute always works on any I have done.

EagleMark
10-10-2011, 09:13 PM
What did you do for the adapter? Just whack out the recieving plug from the 1227747?

JeepsAndGuns
10-11-2011, 02:39 AM
Yep, I found someone with a fried 7747 and just de sodered the female plug from the main board, then sodered the wire directly to the pins. It was actually a roal pain in the ass to make, but I was just very intimadated by the pcm and I just wanted to be able to plug my old ecm back in and be able to drive it if the tuning process took a long time.
Ha, I never plugged the old 7747 back in once I plugged in the 7427.

I do have a couple questions about the wiring change over diagram. I saw no input for the crank signal (7747 pin C9), I didnt notice this when making the adapter, but when I swapped all the pins into the pcm plugs last night, I had that left over. I figure the pcm doesnt use this? If not I will just remove it from the harness.
Also, the 7747 had two power inputs, B1 and C16. But the 7427 only had one, I'm guessing the other one just gets removed?
And last, are the 7427 pins E14 and F14 inputs or outputs? The diagram shows both of those pins going to the old pin C14. But there is only 1 C14. So do I need to splice into the old C14 wire and add another wire so I can hook one to E14 and the other to F14? Thats what I did on the adapter, I just tied both together and connected it to pin C14

http://img.photobucket.com/albums/v606/JeepsAndGuns/2011-10-02092120.jpg

Six_Shooter
10-11-2011, 02:46 AM
The '7427 does not use a crank signal input. Originally this would have been connected through the 3A "CNK" or "CRNK" fuse in the fuse panel.

The others I have to look at the at the wiring diagrams to remember before commenting.

dave w
10-11-2011, 05:37 AM
I do have a couple questions about the wiring change over diagram. I saw no input for the crank signal (7747 pin C9), I didnt notice this when making the adapter, but when I swapped all the pins into the pcm plugs last night, I had that left over. I figure the pcm doesnt use this? If not I will just remove it from the harness.
Also, the 7747 had two power inputs, B1 and C16. But the 7427 only had one, I'm guessing the other one just gets removed?
And last, are the 7427 pins E14 and F14 inputs or outputs? The diagram shows both of those pins going to the old pin C14. But there is only 1 C14. So do I need to splice into the old C14 wire and add another wire so I can hook one to E14 and the other to F14? Thats what I did on the adapter, I just tied both together and connected it to pin C14


The below information is directly from the notes on Thridgen.org

Old C14 is a 5 Volt Reference and goes to New E14.
Old B1 Battery Volts - goes to New E16
Old C16 Battery Volts - goes to New E13 (Input in place of Brake Switch)

**F14 is not listed in the notes from Thridgen.org.
***1994 Wiring Schematic I have shows F14 as a TPS 5V Reference.
****On the '427 conversions I've done F14 is not wired, nothing going there, not needed for anything!

dave w

EagleMark
10-11-2011, 06:12 AM
Taking notes as I build the 427 system for sons truck... yes I am procrastinating...

[attachment=0:pcy1jgip]427.jpg[/attachment:pcy1jgip]

JeepsAndGuns
10-12-2011, 02:38 AM
The below information is directly from the notes on Thridgen.org

Old C14 is a 5 Volt Reference and goes to New E14.
Old B1 Battery Volts - goes to New E16
Old C16 Battery Volts - goes to New E13 (Input in place of Brake Switch)

**F14 is not listed in the notes from Thridgen.org.
***1994 Wiring Schematic I have shows F14 as a TPS 5V Reference.
****On the '427 conversions I've done F14 is not wired, nothing going there, not needed for anything!

dave w


I wasnt sure about the E14 and F14, thats why I wanted to check. Seems I remember on the 7747 system, the 5 volt refrence from the ecm goes out in the harness and then splits off and connects to the tps and map, where it appears on the original pcm harness, it must run them seperate.
I forgot to ask about that brake switch input (E13) I have had nothing connected to that pin the whole time I have been running my adapter. Everything has seemed to be ok. The diagram I have says its power when brakes are not applied, and no power when brakes are applied. So I guess its just been thinking I have had the brakes on all this time...lol

EagleMark
10-12-2011, 03:11 AM
The brake wire your talking about, I beleive is for lockup converter. Hence no brakes means it has power to lockup, brakes applied and unlock. It is needed for 700R4 on 7747. IIRC. I don't see a need for it on a manual... unless the 427 does something differant.

EagleMark
10-16-2011, 03:07 AM
Well I got my first 427 from scratch running on the bench today and this seems to be the 427 beginner thread so I have a couple questions.

Does the 427 act differently then the 7747 in that when turned on the check engine light comes on and stays on without a blink?

Does the 427 act differently then the 7747 in that when turned on the fuel pump runs continuously? No prime then off?

That's what mine is doing and I'm not sure if I have something wired wrong?

Check engine light goes off when I spin the distributor and I do have spark, injector firing, IAC moving all looking good but have not hooked up for data yet.

gregs78cam
10-16-2011, 03:38 AM
I cannot tell you about my check engine light as I don't have it hooked up, but as far as the fuel pump running there is a parameter for time for fuel pump to run before DRP, I suggest check that to make sure it's not set to something unreasonable. I think mine primes for five seconds. I just remembered I will be driving the Camaro to work tomorrow, I can put the DMM on the CEL wire and see about that in the morning.

EagleMark
10-16-2011, 04:16 AM
Cool! Someone may know for sure. But I am used to seeing the flash of check engine light and fuel pump (hanging on wall) turning on, then off till run. So this is all new to me.

I'll be hooking up the AutoProm tonight and starting with one of these manual bin files 1Project2Many gave us earlier. Then get to use the sweet Defs that 93V8S10 built for TP. I'm excited to finally get this far.

Oh yeah there's an update for TunerPro V5 that fixed the data tracing!!! This is like the best day ever!!!

:jfj: :jfj: :jfj: :jfj: :jfj: :jfj:

EagleMark
10-16-2011, 05:28 AM
In comparing a BMHK OE Manual bin to a BJDR OE Auto bin, the manual has Flag set for Throttle Kicker and the Auto does not!

Haven't looked at the millions of other things in IAC logic but I think starting with a manual bin is going to be much better!

EDIT: WOW! Lots of IAC and other changes from Manual to Auto!!! Although the BMHK I started with was for a 7.4L all I have changed so far is TBI LBS Per HR and Cylinder Volume, unchecked a few flags like EGR, disabled EGR via temp. Should be a good starting point for the new IH engine.

EagleMark
10-16-2011, 06:11 AM
I do have a couple questions about the wiring change over diagram. I saw no input for the crank signal (7747 pin C9), I didnt notice this when making the adapter, but when I swapped all the pins into the pcm plugs last night, I had that left over. I figure the pcm doesnt use this? If not I will just remove it from the harness.
Also, the 7747 had two power inputs, B1 and C16. But the 7427 only had one, I'm guessing the other one just gets removed?
And last, are the 7427 pins E14 and F14 inputs or outputs? The diagram shows both of those pins going to the old pin C14. But there is only 1 C14. So do I need to splice into the old C14 wire and add another wire so I can hook one to E14 and the other to F14? Thats what I did on the adapter, I just tied both together and connected it to pin C14


The below information is directly from the notes on Thridgen.org

Old C14 is a 5 Volt Reference and goes to New E14.
Old B1 Battery Volts - goes to New E16
Old C16 Battery Volts - goes to New E13 (Input in place of Brake Switch)

**F14 is not listed in the notes from Thridgen.org.
***1994 Wiring Schematic I have shows F14 as a TPS 5V Reference.
****On the '427 conversions I've done F14 is not wired, nothing going there, not needed for anything!

dave w
There must be a 5 volt reference signal in the 7747 that is tied together IIRC.

I started with an OddBall harness that did not have 7747 or 427 plugs, but did have heated O2? I forget what the ECM was.

But I do have F14 Gray wire to TPS.

Just looked and 7747 does have a 5 volt reference tied from MAP to TPS. That is why a conversion from 7747 does not use F14 but 427 does...
[attachment=0:swes0ow7]747ecm7.jpg[/attachment:swes0ow7]

Six_Shooter
10-16-2011, 06:37 AM
No CEL blink and continuous running fuel pump is a sure indication of Limp Home Mode.

EagleMark
10-16-2011, 07:49 AM
No CEL blink and continuous running fuel pump is a sure indication of Limp Home Mode.
Well don't know what I did, now running on AutoProm not the origanal chip, but now the fuel pump comes on then off at key on just like a 7747. But the CEL does not blink. CEL goes off and stays off while drill is running the distributor. No error codes set. CEL still does not blink when I go key on? AH! May be the way I have the Test CEL wired I have hanging on the wall, Nope! The light bulb I have wired and hanging on wall blinks with a 7747, but must be to big for 427. I wired in a smaller dash type bulb, instead of a tail light bulb and it blinks when key on! Wierd?

System is running on the bench and I had a High MAP error, forgot the vacuum pump, it went away. Then I got a knock sensor error because I did not have a knock sensor hooked up nor do I have one. So I wired a few resisters in series to measure 4k and that error went away to. I did change a setting I thought was in Scalers but can't find it now? It was VSS not from DRAC or something like that. So with that changed and a 4K resister = no codes! :wtg:

EDIT: Found the Output speed not from DRAC in Flags 4L80E Tranmission Paremeters. This was unchecked, I checked it and used a 4k resister and no error code set. Have not tested for MPH.

Rewired, tested, emulated and datlogged on the bench and ready to install on the truck!

Thanks for the help! :rockon:

EagleMark
10-16-2011, 08:21 AM
One question on VSS signal? It's the only wire I don't have done. Wiring diagram shows 2 wires from VSSB to PCM at F12 and F13. When not using a VSSB/DRAC what one to use? Or does one go to VSS and one come back?

And I don't see any Park/Neutral switch wire on the 427 wiring diagram? But it's pretty late and I'm wore out...

JeepsAndGuns
10-16-2011, 04:48 PM
Wow, yall have been busy posting while I have been asleep :laugh:

To try and answer a few questions.
When I first installed my 7427 and put the eeprom in backwards, it had a constant cel and the fuel pump stayed running, so it sounds like you were in limp home mode, like mentioned above. Also I coudnt get aldl connection when I had the chip in backwards.
With everything running, yes, my cel flashes just like the old 7747 did when I turn the key on and the fuel pump cycles.

I just checked a 7747 harness I pulled from the junkyard for resale and yes, the 5 volt refrence splits off a few inches from the ecm and then goes to the map and tps. Where the 7427 seperates them.

The BMHK is the same bin I am using, I think its a good bin to start with if your running a manual. Even though its a manual bin (confirmed by a chevy dealer) I still had to change a couple settings in it according to the paramiter comments in the defination. There was one flag called something like enable shift light (or something like that, I dont have my laptop turned on right now) and it disables the auto trans controlls and sets it up for manual. Make sure thats checked, and the comments box says there is a table that has to be set to all 0, and it wasnt. So I changed it. I also went through and turned off every error code for transmission (just to be safe)

six shooter posted up good info in the vss thread. He says the pcm gets both the 40 pulse signal on F12 for trans controlls, and speed signal from the buffer on F13 for other stuff (the diagram I have says fuel cutoff) I used that diagram you have posted on here in another thread and it says to connect A10 to F12, when according to all this, it looks like it should actually be hooked to F13. I have mine hooked to F12. I will try and switch it today and report back with my findings.

EagleMark
10-16-2011, 05:07 PM
In re reading the 427 conversion thread, yes it looks like VSS should go to F13.

viewtopic.php?f=9&t=206 (http://www.eagle-mark.com/Forums/viewtopic.php?f=9&t=206)

Six_Shooter
10-16-2011, 08:40 PM
F13 is the wrong pin for the '7747 swap. The F13 pin is the 40 PPR signal, for e-tranny controls.

There is no Park/Nuetral wire on the '7427, since it used "range switches" in the tranny that are 3 connections that tell the PCM exactly what gear the tranny is in. It would come down to ground two of the inputs and switching the 3rd one with park/nuetral IIRC.

EagleMark
10-16-2011, 09:35 PM
So is F12 the correct input? The 7747 to 427 conversion writeup says F13... or should I say what do you use for VSS without DRAC/VSSB to input into 427?

Six_Shooter
10-16-2011, 10:06 PM
F13 is NOT in anyway shape or form correct for the '7747 to '7427 swap.
F13 is used for tranny controls and needs a 40 PPR input.
F12 is for other functions and uses a 4 PPR input.

EagleMark
10-16-2011, 11:07 PM
Is there any paremeter adjustments for VSS coming in F12. I can't find any yet but have read guys change something to use a 2 PPR VSS?

Or just bluntly tell me what VSS I need? I'm getting a headache with all the misinformation I am reading? ... :mad1:

:rockon:

JeepsAndGuns
10-17-2011, 02:33 AM
F13 is NOT in anyway shape or form correct for the '7747 to '7427 swap.
F13 is used for tranny controls and needs a 40 PPR input.
F12 is for other functions and uses a 4 PPR input.

I think I am going to have to disagree with this.
Here are my findings as of today:
I had my speed sensor hooked to pin F12, and it wasnt displaying any speed in the datalog. I changed the setting in the bin for "input not from drac" and tried again. Still nothing, speed was not displaying.
Next I took and swapped my speed sensor wire from F12 over to F13 and tried again. TA-DA! I now have a working speed signal in the datalog! I was thinking it was going to be off, since what I was reading said it should be 4 pulse and not 2 pulse. But I started driving and the speed in the datalog was reading exactly the same as the spedo in my dash. :jfj:
Now the fuel usage/mpg part of the datalog works, and it also goes into full DFCO. When driving it before, I would watch the injector bpw drop to .49 when I would let off the gas, and decel would work way better than it did with the old 7747. I thought I was in dfco when it dropped to .49, wrong! Now, when I let off the gas, after a second or two, when the computer senses I am slowing down, the bpw drops to 0, full fuel cut off! When it does that, you can feel the decel get even stronger. I really like this PCM! Once you get below a specific rpm, you can actually feel it turn the fuel back on, it does just a little burp/blip when it does. But nothing annoying or anything.

So from my findings today, I can state the following as correct and tested by me:
Speed sensor connects to pin F13, set "input not from drac" and the two pulse vss I got from jtr is working perfectly fine with the 7427.
F12 is the 40 pulse, trans output shaft speed sensor, used for shifting. I think you got the inputs mixed up in your comment posted above.

Six_Shooter
10-17-2011, 03:52 AM
Odd, mine was the opposite.

I ended up going to a DRAC anyway, because of the 4L60E that eventually went in the truck.

JeepsAndGuns
10-18-2011, 02:11 AM
If your running a 4L60E, I would assume your using the 0D code mask? I am running a 454 manual trans bin that uses the 0E code mask. Could this be the diffrence?

Six_Shooter
10-18-2011, 02:54 AM
Possibly...

I thought you were using $0D....

I'll look at $0E stuff from now on in regards to this thread. lol

EagleMark
10-18-2011, 03:34 AM
Is'nt $OE really for 4L80E? and $OD for 4L60E? I think they can do both but something somewhere made me think this?

1project2many
10-18-2011, 06:32 AM
There are some pretty significant differences between 60E and 80E control strategies. The ecmguy hacs don't list any $0E cals for a 4L60E or any $0D cals for an 80E so with no further info I'd bet they are trans specific. Now there's also the $E6 cal for the '8625 which was superceded to the 7427. That cal was designed to work with the E and non-E version of the 4L60 trans. And there's the $63 which was used in the 7427 in an exported vehicle (you have to be curious about why GM used a different code mask for an exported vehicle!) That cal is also for E, non E, and manual trans vehicles.

With the different mask id's available, the only way to be sure a specific cal uses a specific pin is to have the wiring diagram available. I may be able to dig out a few diagrams if needed, as long as there's no rush. :)

Oh, and DRAC info attached (finally)

EagleMark
10-18-2011, 08:11 AM
OK I'm curious why a seperate mask for export? Only because I have an LT1 and there was an export LT1, same PCM and mask, that had pipes available from chevy with no cats. But they came with O2 sensors AND ran open loop!!! Got a bin file from a guy in Dubai, car has O2 sensors, all turned off in bin! Now how does that make sense? Two heated O2 sensors in a car running open loop AND leaded fuel!!!

Back on topic... isn't the $85 the same PCM as all these we are talking about here? Man GM was going nuts back then with all same/simalar PCM and so many masks. Why?

Six_Shooter
10-18-2011, 08:37 AM
$85 was used the 16147060 PCM. Not an easy PCM to find. A friend of mine has one installed in his '71 Cutlass, with a quad 4 bbl throttle body (pictures are posted elsewhere on this site), and a 4L80E. AFAIK, they were only used or at least mainly used on the 454/4L80E pick-ups and maybe some of the heavy trucks that had the same driveline, in '92/'93.

The 16147060 PCM has 2 brown connectors that are more reminiscent of the 1227747. Bins are only 32Kb in size, compared to the 64Kb bins of the 16197427.

I have a sorted $85 XDF, that I need to make sure is as complete as possible, and then will upload with the new organization.

EagleMark
10-18-2011, 10:11 AM
There's a guy on CK5 with a $85 I and dave are helping... and I just won an auction for harness and PCM I'm pretty sure was $85 for cheap, I thought the plugs were the same as 427... I may just wire new 427 plugs on it? There's no ADX for that mask on TP? Thanks for the info! :happy:

Six_Shooter
10-18-2011, 04:28 PM
I also have a decent ADX. I started with one that is on moates IIRC, or maybe it was an ADS. I've added a dashboard or two to it. I can send that to you.

No, the plugs are definitely different between the '7060, and '7427.

EagleMark
10-18-2011, 05:14 PM
Since you have a XDF and ADX I would probably just build this PCM harness into something simple.

Is the chip a memcal or chip like 7747? Sounds like an odd PCM but others make it run fine...

JeepsAndGuns
10-18-2011, 06:59 PM
And what about the $31 code mask? I have two 7427 pcm's I got from the local pull a part and both had the same BCC witch came up as $31 code mask. One was in a 3500 dually, not sure what engine, as it was already gone, but I think a 350, cause thats what the BCC comes up as. The other pcm came out of a 95 chevy van 30. (full size van, no windows)
Soo many code masks for the same pcm. Its kinda confusing.

EagleMark
10-18-2011, 07:16 PM
I agree. But $31 XDF and ADX are available at TunerPro.

That brings up a question? If you have one of these $OE can you use $OD or if $31 can you use $OE?

I beleive I already went from $OD to $OE on this 427 and it runs fine on my test bench.

Six_Shooter
10-18-2011, 07:41 PM
The '7060 is a MEMCAL.

You can swap between code masks with the '7427, as long as it was used in that PCM.

I have some info on $31, but it doesn't seem to be any where near as popular as $0D and $0E.

1project2many
10-18-2011, 07:55 PM
I don't know why GM made a different cal for export. I have a few export cals and the differences are usually related to leaded fuel (O2's and closed loop disabled, cat converter models different) or speed limiters (none in the cal I've got.)

I believe I have a def file (not TP) for $31. Does anyone know of a handy utility to convert a non-TP def to TP?? And if ecmguy released a hac, I probably have that also. You can swap between cals if they're intended for the same pcm but you need to check the wiring diagrams because GM sometimes makes subtle changes to the input / output functions. It makes more sense to me to make one pcm and a million different masks than to make a million different ecm's and only one or maybe two masks for that pcm.

EagleMark
10-18-2011, 08:10 PM
But why not one PCM and one mask? Seems like $OE can do 4l60e, 4l80e, 700r4 and manual IIRC looking through the mask. Maybe GM had multiple teams working on and sharing simalar PCMs and tech? Or... I just can't figure why, but I am simple and GM is complex, and has to comply with EPA...

EDIT: In looking at $OE it does have bins and paremeters for manual and controls and Auto 4l80E and 700R4. But does not have 4L60E.

JeepsAndGuns
10-19-2011, 02:23 AM
The 7427 I have was stock with the BJYK BCC, witch is a 0D mask. And like mentioned, I am using a tuned BMHK bin witch is 0E. I am having no pcm problems.
How come there is 0E and 31 masks if they both seem to be for the same applacation (HD truck/van with 4L80E) Why make two masks, who not just use the same one? GM is odd sometimes.
I downloaded the 31 mask from TP so I could look at these bins. But it appears 0E and 31 both use the same datastream defination. Making things more confusing on why is there even a $31 mask?

Six_Shooter
10-19-2011, 04:26 AM
I have 2 $31 .XDFs in my folder.

One is probably very incomplete though, it's only 70Kb in size, while the other is 1161 Kb in size. lol

Six_Shooter
10-19-2011, 06:27 AM
Let's try this...

EagleMark
10-19-2011, 06:32 AM
Thanks Chris!

Got some info on throttle Kickers!!! They were for soliniods and the govener paremeters... topic still underway here.
http://www.fullsizechevy.com/forum/gene ... ost5437704 (http://www.fullsizechevy.com/forum/general-discussion/performance/tbi-tuning-87-95-obd-i-ecm-pcm/485849-throttle-kicker.html#post5437704)

[attachment=0:1bunschm]TBI-Kicker_govener.jpg[/attachment:1bunschm]

JeepsAndGuns
10-19-2011, 03:16 PM
Very interesting. I have never seen a tbi unit that looked like that.
In the bin I am using, it has a tempature to enable throttle kicker. Cant remember the exact temp without looking, but I know it doesnt enable untill the engine warms up just a tad, so when its still cold, it will do the slight/momentairy stumble as I am pulling out. Once it warms up some and the TK enables, I can pull out with no stumble, it just goes.
Well, come to think of it, I dont really have any FIRM proof that it is in fact the throttle kicker feature, it could be some other setting in the bin I know nothing about. But I do know when I disabled the TK, it would do it every time I pulled out, and with it enabled, I pull out no problems. :confused: I will keep an eye on that thread.

EagleMark
10-19-2011, 07:17 PM
Well one guy said yes it is IAC logic and that would corespond to what your saying.

The other guy said it's to control Kicker along with govenor shown in picture, but has not said it has nothing to do with other IAC logic...

So maybe it is both. Wonder if it shows in $OE as that seems to be for Auto and light duty?

I have seen that TBI without big bulk on side. It was on a 366 Chevy truck motor. It has the big bores but smaller injectors with uiuque injectors. They are used on commercail trucks. The one above has the throttle Kicker to raise idle when something like a PTO, welder, airpupmp is turned on.

EagleMark
10-19-2011, 07:36 PM
I had to EDIT one of my earlier posts to make info correct. It states:

EDIT: In looking at $OE it does have bins and paremeters for manual trans and controls and Auto 4l80E and 700R4. But does not have 4L60E.

gregs78cam
10-22-2011, 05:28 AM
It seems to me that when GM started putting the 60E and 80E in they still had some applications with manuals and some with TH400. So they needed PCMs with different abilities in the beginning. Then eventually they superceded the '8625, '7060, '6395 with the '7427 that running $0D or $0E could handle everything and backwards compatible to run the same masks as the old ones. Just my thoughts.

EagleMark
10-22-2011, 05:58 AM
That actually makes sense if you look at the years of the PCMs! :jfj:

JeepsAndGuns
10-22-2011, 04:02 PM
Does seem to make sense.

Heres something new that has started since I have gotten the speed sensor working with the 7427.
When driving along steady and you hold the pedal at the "in between" point, to where you are not accelerating or decelarating, kinda at that point right before you would be in decel, it wants to kinda sputter/miss. I dont know if its really missing, but it just kinda sounds like it. No backfires or anything, you can just feel/hear it in the engine, and its only mild, but enough to be annoying and make you notice that something not quite right. I kinda almost want to discribe it as its like the engine is trying to figure out if it should be in accel or decel. It kinda wants to do it a little more noticeable when its still warming up, and not quite as bad once its fully warmed up, but still does it when warm.
Any ideas on what it might be and what I might try to correct it?

EagleMark
10-22-2011, 04:27 PM
Depends on what TPS %? Sounds like your almost trying to find DFCO...

JeepsAndGuns
10-22-2011, 04:40 PM
I thinking its something the pcm is trying to figure out.
I'll have to do a datalog and see if its at a specific tps, and see what other things are going on when it does it.

Six_Shooter
10-22-2011, 06:03 PM
I would look at timing. I was able to clear up a lot of that low load surge in a few cars by adjusting timing. Depending on the car more timing helped, in others, reducing timing helped.

EagleMark
10-22-2011, 09:41 PM
I hear what your saying but from what he is describing is not low load, it's no load, almost like idle when cruising...

Jeeps and Guns, does it do it if you let throttle completly off? Or just when your trying to find differance between accelerate and decelerate? Or is Six Shooter right and low load (accelerate)?

Six_Shooter
10-23-2011, 12:44 AM
I hear what your saying but from what he is describing is not low load, it's no load, almost like idle when cruising...

Jeeps and Guns, does it do it if you let throttle completly off? Or just when your trying to find differance between accelerate and decelerate? Or is Six Shooter right and low load (accelerate)?

It would be considered low load. "load" does not always mean acceleration, it just means a load on the motor other than to keep itself running, which could also be considered a load, depending on how you look at it.

gregs78cam
10-23-2011, 12:55 AM
My Camaro was doing something similar, only it was very noticable. i found out that it was going lean. I turned off closed loop and it went away. I have a feeling it had something to do with the LM-1 supplying the simulated narrowband input for the ECM. Just don't have time to test it.

So maybe turn off closed loop and see if it goes away. Or look at your log for a lean spike.

EagleMark
10-23-2011, 03:11 AM
Your in trouble JeepandGuns!!! We got three answers for your issue!!! :laugh:

Least you got some input on what to look for... guess a datalog with issue happening may be in order?

dave w
10-23-2011, 07:04 AM
I would look at timing. I was able to clear up a lot of that low load surge in a few cars by adjusting timing. Depending on the car more timing helped, in others, reducing timing helped.

I agree 100% with this statement! I had 3/4 4X4 '427 conversion with excessive low load surge in 4 Lo. I increased the Near Idle TPS% to 7% and tweaked the Near Idle timing table to eliminate the low load surge. Having two timing / ve tables in the '427 is nice!

dave w

JeepsAndGuns
10-23-2011, 04:15 PM
It will stop if I push the gas a little more to make it start pulling a bit, and stops if I let off completely. So its only when I am at the in between spot.

I do remember back when I was building my timing table with the old 7747, that it would make a noise real simillar to this when I didnt have have enough timing. I would be emulating and then raise the timing some in the area and it would smooth out. So it could possiably be timing, I'm not sure. I will will just have to do a log and see if there is anything that sticks out when it does it.
All I know is it never did this with the old 7747, and didnt do it with 7427 untill I got the speed sensor working.

Oh yea, alsmot forgot, it seems to do it when I am putting around in 2nd gear (I have a granny gear 1st) at parking lot speeds. I was thinking about starting to play with the idle timing table some and see what I could do with that. The only question, is tunerpro says its "closed throttle" So does it switch to this table any time the throttle is closed, or what dictates when it goes into this table? Right now I have both tables exactly the same.

EagleMark
10-23-2011, 06:38 PM
[quote="Six_Shooter":rwhyzn21]I would look at timing. I was able to clear up a lot of that low load surge in a few cars by adjusting timing. Depending on the car more timing helped, in others, reducing timing helped.

I agree 100% with this statement! I had 3/4 4X4 '427 conversion with excessive low load surge in 4 Lo. I increased the Near Idle TPS% to 7% and tweaked the Near Idle timing table to eliminate the low load surge. Having two timing / ve tables in the '427 is nice!

dave w[/quote:rwhyzn21]
Man I would not want to tune one of these without emulation! To much stuff! This is just a quick look, but since it started with VSS install it may have to do with MPH paremeter of some kind. Also JeepsandGuns is a conversion so he probobly has done Min Air Adjust, who knows where his TPS% is at idle?

Here's some things I see with advice given, not to say it's one but lots of varibles.

[attachment=0:rwhyzn21]JeepsandGuns.jpg[/attachment:rwhyzn21]

JeepsAndGuns
10-24-2011, 02:19 AM
Ok, I didnt have as much time today as I wanted, but I was able to drive around with the laptop for about half a hour this afternoon.
To first answer the question about min idle. A couple weeks before I did the 7427 swap, I re checked and re set my min idle. With the iac drove all the way closed (by jumping the aldl pins) and then un hooking it when it was closed, I set my min idle to 500 rpm. I then used the super 42 data log screen to re set the tps voltage to .54 volts. On the 7427 0E data stream dash, it shows tps voltage as .6 volts when throttle is closed.

So here is what I noticed today.
I tested at several diffrent speeds, rpm's, and throttle. It seems to be doing this pretty much without fail when tps voltage is .8-.9 volts, and map is around 35 kpa. But it also will do it at most everything between map 30-39, but only at around .8-.9 tps volts. It doesnt matter what speed I am going, or what rpm the engine is at, and since it doesnt matter what rpm, I dont think its going to be timing, as at every rpm and speed I tested, timing was diffrent each time. So it didnt seem to matter what the timing was. And when it was doing it, I paied a little more attention to it this time, and it has just a ever so slight (I mean slight) surge. I watched the datalog dash as much as I could when driving to try and see what was going on (took a long time to narrow it down to the specific tps and map. I couldnt look but a couple seconds before eyes had to go back to the road) But when it was doing it, timing never changed, but injector bpw was bouncing around. It seemed to be jumping between .98 and usally somewhere between 1.08-1.15. I coulnt narrow down the high side, as it was constantly changing. I'm kinda almost wanting to think fuel?

Also, another question, as lots of the tps adjustments in the bin show it as tps %, is there a way to convert tps voltage to tps % if .6 volts = closed throttle.

EagleMark
10-24-2011, 04:16 AM
That's what I was thinking and where I was pointing you, look at data list in ADX file and below TPS voltage is TPS Position! That is your percentage!

Because you have a conversion, nonstock for ECM engine, it is, in my experiance always needed to do min air setting, this changes TPS percent! But when you elongate holes in TPS to adjust back to .54 volts it SHOULD go back to correct TPS percent! But I have noticed in TunerPro ADX files on 7747 that TPS percentage is wrong.

Looking at 427 XDF SO many things happen at idle, off idle and are effected by TPS percent that for example, "TPS to Return to Idle Spark" is set to 2.0% so you may go to 1.9% while driving?

Or "Maximum TPS for Idle VE" set to 2.3% and you let off gas while driving and go to 2.1% while driving?

Not to mention TPS % settings for MPH to idle or off idle or DFCO or? SInce your problem came up after VSS I think it's going to be a TPS% vs MPH setting. Just a guess from start... not really sure how yours ran without VSS as I thought these PCM needed VSS and this whole issue and thread learning experiance shows how important VSS is to this PCM. Although dave w knows how to make them run without? Why take away something that is so much more important to this PCM, compared to 7747.

And several others that I just looked at that change what PCM is doing. Is it idling or is it driving? PCM is confused and could be as little as .1% in TPS angle screwing up driving or idling.

EagleMark
10-24-2011, 04:35 AM
My Camaro was doing something similar, only it was very noticable. i found out that it was going lean. I turned off closed loop and it went away. I have a feeling it had something to do with the LM-1 supplying the simulated narrowband input for the ECM. Just don't have time to test it.

So maybe turn off closed loop and see if it goes away. Or look at your log for a lean spike.
See, your having the same issue and what JeepsandGuns found in datalog was exactly what you said. lean spike. Although could be simulated O2?

Just a theory right now but what everyone has tuned out with fuel and spark may have been a TPS% VS MPH at idle, off idle because of all the paremeters to do with TPS%... just a theory as you all know I am new to this PCM...

JeepsAndGuns
10-25-2011, 03:18 AM
look at data list in ADX file and below TPS voltage is TPS Position! That is your percentage!


I am a little confused about this?
So I bring up the ADX like I did when I entered in my base timing and injector flow?
Or are you saying that tps voltage is percent? Meaning 1.0 volt is 1%, 2.5 volt is 2.5%, .9 volt is .9% ??
What is stock tps voltage when throttle is closed? Should it be .5?

I too was wondering about the VSS, I wonder why I never got the error code for it? How did it run without one? Read my first post and every post up untill I posted that I got it working. It ran fine without it, actually better than fine, it ran better than the old 7747 did.

EagleMark
10-25-2011, 03:46 AM
ADX Aqusition data side. Not XDF bin file side.

Voltage is a reference from TPS sensor and percent is position of throttle blades, based off TPS reading... both show up while connected to ECM and show in data list view.

JeepsAndGuns
10-27-2011, 02:47 AM
It took me a couple days to figure it out, but I now see what your talking about.
I was thinking you had to go to edit adx, and under the tps settings, it would display what voltage equils what tps %.
I had a DUH moment tonight and noticed you said under data list, meaning the data log info! I click on that when I datalog, but I always use the drop down menu and change it to display error codes, I have never even really paid attention to the sensor data part of it.
I will definately watch that next time I get some time to fool with it. Not sure if I will have time this weekend, as saturday is my birthday and my mom is coming in from out of state to spend a few days with me.

EagleMark
10-27-2011, 04:04 AM
You can also watch your recorded data over and over again with Data lists, historygrams, moniters and dashbord. they work while recording data and when playing data back!

JeepsAndGuns
10-28-2011, 02:33 AM
I dont think I have ever reccorded any datalogs. I have always run it connected with the tables to check my fuel. I would then just go inside, make the required changes, burn a new chip then clear the tables out.

EagleMark
10-28-2011, 02:50 AM
Ahhhh! Tuning live!

I do that but after I click connect so I can watch data I also go to "Aqusition" then "Record" when your done you click "Stop" or if you forget and close TP it will remind you to Save As.

Then you can play back anytime, watch slow or fast or frame pause frame pause frame pause... you can find glitches!

JeepsAndGuns
11-13-2011, 05:01 PM
Ok, the update this thread about the above issue. I finally had some time to do some more tuning. I figured first I would try timing. So I fired up the emlator and did a little tweeking. I higlighed the high map areas and simply raised the timing just a little and it has now went away. It just simply wanted more timing!
I also tweeked my idle timing table and pulling out has now improved. Having two timing tables is pretty sweet. Best of both worlds!

EagleMark
11-15-2011, 06:52 PM
Glad you got it tweaked!

The throttle kicker may be in Govenor TBI pictured earlier, maybe not? But there is another one that is a solinoid just like old days bolted onto TBI and kicks the throttle linkage. It's activated by another control box simalar to one that controls EGR. If the guy sends pictures I'll post them up.

One of these days since you worked out the issue with timing, you should turn it off again and see if it does do something else in PCM other than activate soliniod.

gregs78cam
12-06-2011, 12:59 AM
I just got my truck up and running on a '7427 with a TH350 and thought I would add a tip, Pin B6 on this PCM is listed as "not used" but it is infact a 5V reference output. So don't mix it up with the CTS sensor input that goes in pin B8, it causes some issues.:mad1: :rolleye:

JeepsAndGuns
12-06-2011, 02:56 AM
Dont guess we need to ask you how you know this....:laugh:

EagleMark
12-06-2011, 06:34 AM
Dave W just found another pin mistake when using the 16197427 with the 700r4, so we are going to have to redo that write up properly...

EagleMark
12-06-2011, 09:19 AM
I just got my truck up and running on a '7427 with a TH350 and thought I would add a tip, Pin B6 on this PCM is listed as "not used" but it is infact a 5V reference output. So don't mix it up with the CTS sensor input that goes in pin B8, it causes some issues.:mad1: :rolleye:I just looked at the 16197427 wiring diagram and it has nothing from B6... so the directions we have in the 7747 to 97427 are correct, right? You just misplaced a wire?


Just checking because Dave W is making the change he found in the write up.

dave w
12-06-2011, 09:28 AM
Dave W just found another pin mistake when using the 16197427 with the 700r4, so we are going to have to redo that write up properly...

I've done 4 of the '427 PCM this year. Three were TH400, one was a 700R4. I'm having trouble with getting 700R4 TCC to work. The original write up from TGO is for a TBI F-Body. Subsequent posts after the original TGO post state PIN E11 is to be used for the 700R4 TCC control. I have not changed the wiring from E10 to E11 to acknowledge the wiring change will fix the TCC problem I am experiencing.

I added notes to show what differences I found on Full Size Pickups vs the F-Body car. The conversion works as written. I have not been able to find a published wiring schematic showing either a 1994 or 1995 application using PCM '427 PIN B6. I'm sure that a volt meter has confirmed that PCM '427 PIN B6 is a 5V reference, but I'd like to see an actual published wiring schematic showing B5 being wired as a 5V reference.

For TH400 applications that had 1228747 ECM's, I've installed 1973 ~ 1986 TH400 kick down switches on the accelerator pedal, that are wired to supply Ground to the kick down relay.

dave w

gregs78cam
12-06-2011, 10:14 AM
Yea it was my mistake, I made a spreadsheet from the swap info in TGO, some time before the article was posted here, and I screwed it up. Small mistake. But yes with key on B6 shows 5.0 Volts.

EagleMark
12-06-2011, 06:02 PM
Man you had me worried I had to go through this harness I already did, it's hanging on the wall with the PCM ready to put in my kids truck. Since it already ran on my bench and I watched data in TP while emulating I couldn't figure out how that wire for CTS was wrong... it's for a manual trans so I wouldn't have the issue Dave W found for 700r4. Don't understand the issue Jeeps andGuns is talking about because I got data... but his ALDL was from 7747. So I think he found P3 to P4 data (orange wire) is in a differant spot in ALDL port. I never looked and rewired from stock wiring schematic.

The harness I started with was from UnKnown? Plugs wouldn't fit 7747, 427 860... but it had heated O2 and wires for electronic tranny... and some other weird stuff I had never dealt with, I think it was out of a FWD car...

Anyway good work guys! :thumbsup: We know our wiring conversion pin out is accurate!

Greg, is that spread sheet worth posting in the 7747 to 97427 thread?

JeepsAndGuns
12-07-2011, 02:38 AM
Before I installed my ALDL plug, I removed all other wires from it other than the two datalog wires and the ground. One wire is white with a black stripe, the other is orange and I think it had a stripe too, but cant remember. Mabey the 7747 had a stripe, and the 7427 didnt. Its pouring down the rain right now or I would check. I just swapped the pins on the ecm connector and never touched the aldl plug.

gregs78cam
12-07-2011, 05:23 AM
Greg, is that spread sheet worth posting in the 7747 to 97427 thread?

I'll PM you with it, and you can tell me.

JeepsAndGuns
12-22-2011, 03:11 AM
Thought I would add this nice little tidbit of info I have found out while tuning.
As we all know I am running this pcm with a manual trans. Earlyer were were talking about this "throttle kicker" and when I have it disabled, I would have trouble pulling out. I would have to rev up more than I should and feather the throttle as I was letting out on the clutch. Turn it on and it would work a lot better.
But I have always had this slight drop in rpm's as I was pulling out. It was like the engine was straining to pull out. It never did this with the old 7747. I did some tweeking and changing of my idle spark table and it improved it a good bit, but it was still there.
To try and keep the story short I tried a couple diffrent bins a couple weekends ago. They both did a lot worse in other areas and all around, but one thing that was better, it didnt have the drop in rpm's when pulling out. So I started searching for the reason why. I simply copied over my fuel and timing tables, so it shouldnt be them.
I stumble across this scaler close to the bottom of the scalers. Its in the section labeled "IAC AE, PE, DFCO paramiters" In that section there are two scalers called lower and upper threshold for IAC AE.
The bin I am using (BMHK) was set as 3.1% for the lower, and 10.2% as the upper. The other bin had it set as 2.0% for the lower and 2.3% for the upper. So I figured it was worth a try, thinking that as I was pulling out, the IAC was opening and this might give it more fuel when doing so, thinking it might just need a extra shot of fuel when pulling out.
Burnt a chip and gave it a try. BLAMMO, it now pulls out smooth and no more drop in rpm, it now just pulls and goes! Watching the datalog dash as I pull out I can see the AE become active for a split second as I am letting out on the clutch. So its simply giveing my engine what it wanted, witch was just a little extra shot of fuel when pulling out.

Mabey this might help someone in the future. :thumbsup:

EagleMark
12-22-2011, 05:03 AM
That's exactly what it did! AE (Accelerator Enrichment) is your accelerator pump like on a carb! You gave it more AE, I'll bet the manual bin has more AE range in IAC then Auto bin?

gregs78cam
12-22-2011, 05:29 AM
I don't have TP in front of me right now, but I thought there was a bunch of stall saver stuff in the '7427. You might look into those as well. I know that in my '98 Grand Am with the 5 speed it is not easy to stall the engine because the IAC, and fueling helps to prevent it, i.e stall saver. You should be able to ease out of the clutch with out giving it any go pedal without stalling. If it was happening when you add pedal, then yes the AE was needing some tweaking.

JeepsAndGuns
12-22-2011, 03:58 PM
Yea the stall saver is working as far as I know. If I put it in first (this is a wide raito trans, aka granny gear 1st) I can let out on the clutch without touching the gas. But first is not normally used in normal driving, you pull out in 2nd. But in first the iac will open so as to keep the rpms up/keep it from stalling. In 2nd it would do that too, but it just always had that dip in rpm's. It just needed a little extra shot of fuel. I have noticed the 7427 pcm has way better iac logic than the old 7747. The iac even seems to work faster.
I dont think I have ever actually looked at any of the stall saver paramiters. I may check them out next time I have the laptop on.

EagleMark
12-22-2011, 05:14 PM
It has more IAC logic and ever thing else because it has a bigger chip. The IAC is faster because 7747 is 160 Baud rate and 7427 is 8192 Baud rate. 160 Baud is like ever 1.2 seconds and 8192 Baud is so many times a second I forget?

Stall saver on 7747 I had to turn off for a an Off Roaders who wanted complete control of low RPM driving during rock crawling, they would lug and engine and it would rev up because stall saver kicked in, same guy new engine with 8192 baud system on new engine in same rock crawler said he wanted it turned off and I said to try it first, I had already drove it, lugged engine trying to stall with no rev up issue... no need to turn off it works so much faster he can not notice it working. Actually he said is was much easier to crawl because the engine had a rock solid steady RPM at idle and very low RPM he had to do less to operate engine driving and spends more time looking at and planning obsticles driving... although the engine needed a tune do to non stock engine build like cam headers etc... all I did was fuel and spark... there is so much that does not need to be touched on the newer 8192 baud TBI systems.

Next time I work on his truck I am going to look at the AE difference you found that fixed your issue, seems to be something that would improve this type of driving... :happy:

JeepsAndGuns
01-08-2012, 03:49 AM
Well did some more tweaking today and had some good results, so I figured I would just go ahead and keep adding to this thread.

I touched on this a little bit when I got my vss working and dfco started working. When it would come out of dfco, it would jolt the engine when it cut the fuel back on. Basicly it would be like you just lightly bliped the throttle. At first it wasnt annoying, but it kept on untill it did! After a little while it became VERY annoying. Would do it at about 1500 rpm, and I had not gotten to the point when I downshit. (remember, I am running a manual trans)
Well I find this parameter in scalers under "AE parameters" called "post DFCO AE pulse" with the discription that it provides a AE pulse when exiting dfco if no tps increase. I thought that kinda odd. Why would it want to add more fuel when kicking the fuel back on if the throttle did not get re opened. I did drop it straight to zero right away, I took it in steps. The jolt got lighter the lower I went untill i eventually set it to zero. Now it simply cut the fuel back on post dfco, but didnt add any extra AE. The jolt was a lot less that it was, but there was still a jolt (like you bliped the throttle) when it turned the fuel back on.
Now just to keep from confusion, there is still a parameter for a AE pule when exiting dfco if you DO open the throttle. I forgot exactly where it is. But that one makes sense. Your in dfco slowing down and then need to accel again (like slowing down for another car making a turn, then you take off again) I left that setting stock, as it does just fine if I hit the gas again when in dfco.
Now back to the jolt when it kicks the fuel back on. I thought about it and where it kicks it back on at 1500 rpm, it would be nicer if it did it at a lower rpm. I did a little more carefull looking at all the avalable parameters in my xdf, and found something I thought would be usefull. Its under tables and is under dfco parameters and is labeled " minimum dfco rpm vs. temp. In a nutshell its basicly what I was looking for! Its what rpm it cuts the fuel back on post dfco, and it splits it up into diffrent tepatures. I changed it to 1000 rpm for most closed loop temps, and a little highr for colder temps. Saved it, burnt a chip and took it for a drive. Sucess! I now no longer have the jolt when in dfco, because now it doesnt cut the fuel back on while I am still slowing down! It now does the jolt/blip when I push in the clutch to downshift. I watched the rpms and it doesnt drop lower than it should, the fuel cutting back on catches it, and it still does that blip. I now like it, because its like your bliping the throttle in between downshifts. I actually can kinda time it just right and use that blip when double clutching and not even have to touch the throttle. Kinda a added bonus...lol
BUT not all was well. Because I lowered the min rpm, I now made it to where if I was at parking lot/driveway speeds, it will go into dfco! Say like you pull out, drive a few yards while still in first gear and let off again, it went into dfco real quick and then the jolt of cutting the fuel back on, made a interesting combanation, and not a good one. It was like hitting the brakes and the gas real quick.
So some more digging around in the xdf, I find the parameters in scalers under "dfco parameters" and found the two parameters "minimum MPH to enter dfco" and "MPH to disable dfco"
The first one was set to 10 mph. I doubled it to 20 mph. I figured there was no need to go into dfco under 20. I then changed the disable dfco from 7 mph to 15 mph. That way, I have to be going 20 mph or faster for dfco to come on, and under 15mph, dfco is completely disabled.
Saved, burnt a chip and test drive. I now have full sucess! I now have no more jolt when slowing down, have a nice blip in the throttle between downshifts I can use when double clutching (that was completely unexpected, and just kinda a added bonus side effect), and no more dfco at too slow of a speed.

Hopefully all these little updates may help another manual trans 7427 user one day.

one92rs
02-07-2012, 03:38 AM
not to add a pointless post to this thread. but i posted needing info on a 746 to 427 swap in my camaro and a 60e swap from the 700. i cannot tune it myself so i will get a chip. but i needed to know all the info in this thread. now i will be watching closely how all this goes. also can someone in here tell me where to get new plugs for the 4127 ecm.

dave w
02-07-2012, 05:23 AM
not to add a pointless post to this thread. but i posted needing info on a 746 to 427 swap in my camaro and a 60e swap from the 700. i cannot tune it myself so i will get a chip. but i needed to know all the info in this thread. now i will be watching closely how all this goes. also can someone in here tell me where to get new plugs for the 4127 ecm.

Mouser Electronics is where I get my ECM connectors from.

http://www.mouser.com/Search/ProductDetail.aspx?R=12110115virtualkey63000000vir tualkey829-12110115

http://www.mouser.com/Search/ProductDetail.aspx?R=12110113virtualkey63000000vir tualkey829-12110113

dave w

one92rs
02-07-2012, 05:29 AM
thank you very much. i will get those ordered.

1leg
02-07-2012, 06:30 AM
For TH400 applications that had 1228747 ECM's, I've installed 1973 ~ 1986 TH400 kick down switches on the accelerator pedal, that are wired to supply Ground to the kick down relay. dave w

Dave do you have part numbers and pictures you could share on this. I'm might have a 427 soon to start a swap on the suburban.

1project2many
02-07-2012, 06:44 AM
The DFCO pulses are helpful to prevent a "bump" when going from DFCO to normal fuel mode due to the manifold drying out and the delay time to get fuel from the injector to the chamber.

Now that you've tried DFCO that would enable even at minor coastdown, you might appreciate the idea of using brake switch input to force DFCO at any speed. It would save fuel and help save the brakes if driving in traffic.

93V8S10
02-07-2012, 07:09 AM
Now that you've tried DFCO that would enable even at minor coastdown, you might appreciate the idea of using brake switch input to force DFCO at any speed. It would save fuel and help save the brakes if driving in traffic.
Got me interested!

dave w
02-07-2012, 07:48 AM
Dave do you have part numbers and pictures you could share on this. I'm might have a 427 soon to start a swap on the suburban.

The Ebay auction has the part number and pictures.

http://www.ebay.com/itm/Corvette-NOS-Transmission-Kick-Down-Downshift-Switch-TH400-1970-1977-/190625711858?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item2c622d86f2

I made a 3/8" cylindrical sleeve to go around plunger, because the gas pedal arm does not push the plunger far enough.

dave w

EagleMark
02-07-2012, 10:53 AM
Darn that's an expensive switch. Wonder if a regular brake switch used for 700R4 to unlock converter would be chaeper? Anything would be cheaper than NOS Corvette parts...

Jeepsandguns that bin was superceded, so what your tuning may have been the issue they changed it. The other 7.4L manual bin 93V8S10 has may be better? It was not superceded.

Gregscam (can you post that bin) is also getting me a 5.7L Manual bin from a 16197427 but I think it runs $31. I may redo this one for my kids truck or at least compare them all.

93V8S10 can you post up that bin?

gregs78cam
02-07-2012, 11:07 AM
I posted it in my for sale thread, but sure here ya go. It shows at L4008 as $0D.

EagleMark
02-07-2012, 12:01 PM
BCC result page!



BCC used in 1995. (Scroll down for more info)






BCC= BPRW0651

Scan id= 0505

Part number= 16220651



Release date= 02/04/95

Engine size= 5.7

Trans Type= all/no listing



ECM/PCM: ECM #16156930


Used in trucks:


GMC

Possibly used in:


G20 VAN,2WD,3/4 TON

G25 VAN,2WD,3/4 TON





Options:



With GT4 AXLE, REAR, 3.73 RATIO




With L05 5.7L GAS 8 CYL (5.7K) V8 TBI




With NA5 FEDERAL REQUIREMENTS

JeepsAndGuns
02-08-2012, 02:34 AM
Jeepsandguns that bin was superceded, so what your tuning may have been the issue they changed it. The other 7.4L manual bin 93V8S10 has may be better? It was not superceded.

What was it superceded to? BHDC?
I have changed so many things, it will be hard to transfer everything over. But I may try it one day when I am bored.


I thought the brake switch was just for the TCC?
I disabled DFCO below 20mph, its not really needed at speeds slower than that, and like mentioned above, had very bad parking lot manners. The way I have it set now, it pretty much comes on anytime I let off the gas, and works great! I dont really see the need for the brake switch, unless theres more to it.

EagleMark
02-08-2012, 03:46 AM
What was it superceded to? BHDC?
I have changed so many things, it will be hard to transfer everything over. But I may try it one day when I am bored.


I thought the brake switch was just for the TCC?
I disabled DFCO below 20mph, its not really needed at speeds slower than that, and like mentioned above, had very bad parking lot manners. The way I have it set now, it pretty much comes on anytime I let off the gas, and works great! I dont really see the need for the brake switch, unless theres more to it.The bin we started with BMHK when checked on CalData was superceded to BPRJ a bin no one has...

Brake switch was just a sugestion to daves commnet, it was a hijack of your thread, your right it's to disengage TCC.

dave w
02-08-2012, 03:58 AM
What was it superceded to? BHDC?
I have changed so many things, it will be hard to transfer everything over. But I may try it one day when I am bored.


I thought the brake switch was just for the TCC?
I disabled DFCO below 20mph, its not really needed at speeds slower than that, and like mentioned above, had very bad parking lot manners. The way I have it set now, it pretty much comes on anytime I let off the gas, and works great! I dont really see the need for the brake switch, unless theres more to it.

Brake Switch? I was thinking the question was for a TH400 Kick Down Switch?

dave w

EagleMark
02-08-2012, 04:48 AM
I was suggesting useing a TCC brake switch (cheap) to a NOS corvette part (expensive), it's just a switch... $75?

dave w
02-08-2012, 06:10 AM
I was suggesting useing a TCC brake switch (cheap) to a NOS corvette part (expensive), it's just a switch... $75?

Ok, I get it. Apples and Oranges.

TH400 Kick Down switch is used on '427 PCM conversion to kick down a TH400 like the old 1228747 ECM did. The '427 PCM can't send "ground / battery negative" to the TH400 kick down relay like the old 1228747 ECM did.

TCC Brake Switch to DFCO? Not sure I understand how a TCC Brake Switch helps DFCO? I think I understand DFCO, hit the brakes then the DFCO programming happens.

dave w

dave w

EagleMark
02-08-2012, 09:01 AM
TCC Brake Switch to DFCO? Not sure I understand how a TCC Brake Switch helps DFCO? I think I understand DFCO, hit the brakes then the DFCO programming happens.

dave w

dave wI'm not sure how that became part of this discussion? He was talking of DFCO and we hijacked then it got combined? No coralation between switches and DFCO...

JeepsAndGuns
02-08-2012, 03:33 PM
The bin we started with BMHK when checked on CalData was superceded to BPRJ a bin no one has...

Brake switch was just a sugestion to daves commnet, it was a hijack of your thread, your right it's to disengage TCC.

So is the BHDC spoken about, a newer manual trans bin?

EagleMark
02-08-2012, 06:38 PM
Mixed info? CalData says it's manual. greg78cam said and read it to be from auto, Read last post here:
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?183-NEEDED-16197427-5.7L-Manual-Trans-bin&p=4789#post4789

1project2many
02-21-2012, 09:09 PM
I thought the brake switch (http://shop.ebay.com/i.html?_nkw=brake+switch) was just for the TCC?
I disabled DFCO below 20mph, its not really needed at speeds slower than that, and like mentioned above, had very bad parking lot manners. The way I have it set now, it pretty much comes on anytime I let off the gas, and works great! I dont really see the need for the brake switch, unless theres more to it.

GM went to a lot of work to make vehicles coast when you let off the gas. Overrunning clutches in the auto trans allow the engine to idle down without slowing the vehicle down and vehicles with TCC are designed to release the TCC when the throttle is closed. The whole point is to save fuel by allowing you to coast down hills or to ease off the throttle when it's not needed. With your settings there's no way to do this. Brake switch input would allow a way to engage DFCO only when the vehicle is being slowed. And with a manual trans or an auto with the shifter in a lower range, you'd have engine braking to help slow the truck.

EagleMark
02-21-2012, 09:53 PM
TH400 Kick Down switch is used on '427 PCM conversion to kick down a TH400 like the old 1228747 ECM did. The '427 PCM can't send "ground / battery negative" to the TH400 kick down relay like the old 1228747 ECM did.

dave wDo you have any wiring info on this to 1228747? We are trying to figure if 1227747 can be swapped in it's place...

dave w
02-21-2012, 10:34 PM
Do you have any wiring info on this to 1228747? We are trying to figure if 1227747 can be swapped in it's place...

So I'm wanting to make sure I understand the question. You need the '8747 TH400 Kickdown Relay Wiring schematic? You are swapping out an '8747 and installing a '7747? I have schematics on my home computer, but I'm at work now. Later this evening I should be able to post back the '8747 TH400 Kickdown Relay Wiring. The parameters for the '8747 TH400 Kickdown Relay are different than the '7747 TCC lock / unlock parameters. I think if I were to swap out an '8747 and install a '7747, I would install a TH400 gas pedal kickdown switch to send ground to the TH400 Kickdown Relay.

dave w

EagleMark
02-22-2012, 01:27 AM
Yes I'd like to have them as I don't know how it works and would like too!

Thanks for the info! So same switch in trans would work triggered elsewhere? Right?

woody80z28
02-22-2012, 05:25 PM
Well did some more tweaking today and had some good results, so I figured I would just go ahead and keep adding to this thread.

I touched on this a little bit when I got my vss working and dfco started working. When it would come out of dfco, it would jolt the engine when it cut the fuel back on. Basicly it would be like you just lightly bliped the throttle. At first it wasnt annoying, but it kept on untill it did! After a little while it became VERY annoying. Would do it at about 1500 rpm, and I had not gotten to the point when I downshit. (remember, I am running a manual trans)
Well I find this parameter in scalers under "AE parameters" called "post DFCO AE pulse" with the discription that it provides a AE pulse when exiting dfco if no tps increase. I thought that kinda odd. Why would it want to add more fuel when kicking the fuel back on if the throttle did not get re opened. I did drop it straight to zero right away, I took it in steps. The jolt got lighter the lower I went untill i eventually set it to zero. Now it simply cut the fuel back on post dfco, but didnt add any extra AE. The jolt was a lot less that it was, but there was still a jolt (like you bliped the throttle) when it turned the fuel back on.
Now just to keep from confusion, there is still a parameter for a AE pule when exiting dfco if you DO open the throttle. I forgot exactly where it is. But that one makes sense. Your in dfco slowing down and then need to accel again (like slowing down for another car making a turn, then you take off again) I left that setting stock, as it does just fine if I hit the gas again when in dfco.
Now back to the jolt when it kicks the fuel back on. I thought about it and where it kicks it back on at 1500 rpm, it would be nicer if it did it at a lower rpm. I did a little more carefull looking at all the avalable parameters in my xdf, and found something I thought would be usefull. Its under tables and is under dfco parameters and is labeled " minimum dfco rpm vs. temp. In a nutshell its basicly what I was looking for! Its what rpm it cuts the fuel back on post dfco, and it splits it up into diffrent tepatures. I changed it to 1000 rpm for most closed loop temps, and a little highr for colder temps. Saved it, burnt a chip and took it for a drive. Sucess! I now no longer have the jolt when in dfco, because now it doesnt cut the fuel back on while I am still slowing down! It now does the jolt/blip when I push in the clutch to downshift. I watched the rpms and it doesnt drop lower than it should, the fuel cutting back on catches it, and it still does that blip. I now like it, because its like your bliping the throttle in between downshifts. I actually can kinda time it just right and use that blip when double clutching and not even have to touch the throttle. Kinda a added bonus...lol
BUT not all was well. Because I lowered the min rpm, I now made it to where if I was at parking lot/driveway speeds, it will go into dfco! Say like you pull out, drive a few yards while still in first gear and let off again, it went into dfco real quick and then the jolt of cutting the fuel back on, made a interesting combanation, and not a good one. It was like hitting the brakes and the gas real quick.
So some more digging around in the xdf, I find the parameters in scalers under "dfco parameters" and found the two parameters "minimum MPH to enter dfco" and "MPH to disable dfco"
The first one was set to 10 mph. I doubled it to 20 mph. I figured there was no need to go into dfco under 20. I then changed the disable dfco from 7 mph to 15 mph. That way, I have to be going 20 mph or faster for dfco to come on, and under 15mph, dfco is completely disabled.
Saved, burnt a chip and test drive. I now have full sucess! I now have no more jolt when slowing down, have a nice blip in the throttle between downshifts I can use when double clutching (that was completely unexpected, and just kinda a added bonus side effect), and no more dfco at too slow of a speed.

Hopefully all these little updates may help another manual trans 7427 user one day.

Interesting. I'll be playing with this as well.

dave w
02-23-2012, 12:16 AM
Yes I'd like to have them as I don't know how it works and would like too!

Thanks for the info! So same switch in trans would work triggered elsewhere? Right?

The attached wiring schematic shows both the TH400 Kickdown Relay and the TCC wiring. Pin A7 on the '8747 is wired as either AT Kickdown / Shift Light (manual trans). Pin A7 on the '7747 is wired as either TCC / Shift Light (manual trans).

The pictures below shows a TH400 accelerator / gas pedal mounted kickdown switch. I would image most any junkyard that specializes in light truck would have a TH400 accelerator / gas pedal mounted kickdown switch.

The wiring is very basic. Remove Pin A7 from the '8747 and connect the wire from Pin A7 to one (does not matter which one) of the termianls on the TH400 accelerator / gas pedal mounted kickdown swich. The other terminal of the TH400 accelerator / gas pedal mounted kickdown swich is wired to Battery Negative. Adjust the TH400 accelerator / gas pedal mounted kickdown switch as outlined in a GM service manual. Sometimes a thick rubber hose needs to be installed on the tan plastic plunger of the TH400 accelerator / gas pedal mounted kickdown switch to get the kickdown where you like it.

dave w

JeepsAndGuns
02-23-2012, 03:08 AM
GM went to a lot of work to make vehicles coast when you let off the gas. Overrunning clutches in the auto trans allow the engine to idle down without slowing the vehicle down and vehicles with TCC are designed to release the TCC when the throttle is closed. The whole point is to save fuel by allowing you to coast down hills or to ease off the throttle when it's not needed. With your settings there's no way to do this. Brake switch input would allow a way to engage DFCO only when the vehicle is being slowed. And with a manual trans or an auto with the shifter in a lower range, you'd have engine braking to help slow the truck.

I guess some of it comes down to personal prefrence. I like mine just the way it is. When I let off the gas, I want it to slow down. If I didnt want to slow down I wouldnt have let completely off the gas. If I want to coast without it being in dfco, then I will just shift into neautral.




Interesting. I'll be playing with this as well.

I am still verry happy with the changes I have made. Cant think of anything to do with dfco I would change right now. I have gotten good at using the blip it does when cutting the fuel back on, when double clutching while downshifting.

1project2many
02-23-2012, 11:32 AM
I'm not telling you to make a change. I asked if you were interested in a modified approach. One of the downsides to DFCO enabled with nearly every decrease in load or throttle angle is an offsetting AE pulse or rich VE table to make up the difference when you resume speed. This can end up using a lot of unnecessary fuel. Like pumping the gas over and over on an old carby engine. Using a brake switch input is one way to ensure DFCO isn't active if all you're doing is letting off the gas for a short time, for example when changing lanes on the highway or turning a corner in traffic.

Out of curiousity, what's your final drive ratio and what size tires are you running?

JeepsAndGuns
02-23-2012, 03:48 PM
No clue on final drive ratio. But I have a wide ratio T-18 4 speed (granny gear first gear) so 4th is 1:1, axle gear ratio is factory at 3.54, and I am running 31X10.50's.

EagleMark
02-23-2012, 04:14 PM
I'm not telling you to make a change. I asked if you were interested in a modified approach. One of the downsides to DFCO enabled with nearly every decrease in load or throttle angle is an offsetting AE pulse or rich VE table to make up the difference when you resume speed. This can end up using a lot of unnecessary fuel. Like pumping the gas over and over on an old carby engine. Using a brake switch input is one way to ensure DFCO isn't active if all you're doing is letting off the gas for a short time, for example when changing lanes on the highway or turning a corner in traffic.

Out of curiousity, what's your final drive ratio and what size tires are you running?I always wondered why DFCO was such a small window. Maybe this is where Decel Enleanment comes in?


No clue on final drive ratio. But I have a wide ratio T-18 4 speed (granny gear first gear) so 4th is 1:1, axle gear ratio is factory at 3.54, and I am running 31X10.50's.That should be a real good higway cruiser!

I had Wide ratio (granny low) on a Scout and the granny low was great off road. But made it a 3 speed on street driving. On a street only Scout I had I put in a close ratio trans and got to use all 4 gears. 4th was still 1 to 1 ratio.

woody80z28
02-23-2012, 05:07 PM
I'm still getting used to the gearing on my 1-ton 5spd. I rarely use 1st and the gear splits are huge! (5.61 / 3.44 / 1.71 / 1.00 / 0.73) Can't exactly speed shift in it either...the syncros need a little time to line up those heavy gears.

JeepsAndGuns
02-24-2012, 02:36 AM
That should be a real good higway cruiser!

Around town, and whatnot, yes. But actual highway, NO. I'm running about 3100 RPM at 70 MPH. Kinda screaming! I need a overdrive to get me around 2500 rpm. That seems to be its sweet spot crusing rpm. My engine as its built is not a high RPM engine. Its built more twards low rpm torque, rv style cam (comp cams 256H XE)
It pull great, but there is a still a pretty good diffrence spread in gear ratios, as you dont use 1st for normal driving.

EagleMark
02-24-2012, 05:10 AM
33 inch tires! :jfj:

JeepsAndGuns
02-24-2012, 03:44 PM
Going bigger. My future build for this jeep is as follows, (and I already have the listed parts)

High pinion driver side drop, kingpin dana 60 front axle (need to buy locker and finish rebuilding)
Smooth bottom, factory disc brake dana 60 rear (need to buy gears and lockers)
Early chevy NV4500 trans, with the lower 6.34 first gear (I have completely rebuilt it)
NP-205 transfer case, driver side drop ford version (completely rebuilt)
SOA on the front, shackle inversion on the rear (for about 7 inches of lift on stock springs)
35x12.50-16.5's BFG MT's (bought used, but nearly 95% thread)
Re centered hummer 12 bolt beadlock wheels, pvc beadlock rings. (need to cut out old centers and weld in new ones)
I will be running 5.13 gears, and lockers front and rear.

woody80z28
02-24-2012, 06:13 PM
Going bigger. My future build for this jeep is as follows, (and I already have the listed parts)

High pinion driver side drop, kingpin dana 60 front axle (need to buy locker and finish rebuilding)
Smooth bottom, factory disc brake dana 60 rear (need to buy gears and lockers)
Early chevy NV4500 trans, with the lower 6.34 first gear (I have completely rebuilt it)
NP-205 transfer case, driver side drop ford version (completely rebuilt)
SOA on the front, shackle inversion on the rear (for about 7 inches of lift on stock springs)
35x12.50-16.5's BFG MT's (bought used, but nearly 95% thread)
Re centered hummer 12 bolt beadlock wheels, pvc beadlock rings. (need to cut out old centers and weld in new ones)
I will be running 5.13 gears, and lockers front and rear.

Do you really think you'll need the deep NV4500 granny gear and 5.13 gears? My truck is probably a similar weight to your Jeep and with the 5.61 1st and 3.73 with 33s I rarely ever use it. And with the 3.73 and 33s the cruising RPM isn't bad on the highway.

EagleMark
02-24-2012, 06:47 PM
Having lower first gear really helps when doing rock crawls or other obstacles and gives tremendous control. My sons Toyota has the Trail gear 4:70 to 1 ratio gears and it is incredible, can just about idle over all obstacles, but he is now adding a second transfer case with stock gears as well.

PJG1173
02-24-2012, 06:59 PM
IDK 5.13 with 35's is still a bit much with a v8 and that transmission. I use this site to compare crawl ratios and final drive ratios www.grimmjeeper.com/gears.html (http://www.grimmjeeper.com/gears.html) It is very useful since it allows you to compare two different ratios side by side.

EagleMark
02-24-2012, 07:09 PM
You can go ridiculously low as what my son is doing! I had wide ratio T19 trans 6.xx first gear, and a Dana 20 transfer case 2 to 1 low range and 4:11 axle gears and 36 inch tires which was fine for me, crusied nice on highway, crawled great off road.

PJG1173
02-24-2012, 07:16 PM
what engine does your son's toyota have? It probably needs the extra gearing to multiply torque.

EagleMark
02-24-2012, 07:23 PM
22re, .060 over, head shaved, port match, crawler cam balanced bottom... 5:13 gears, lockers, 36 inch tires. He's really fine where he's at, never has a power issue as is, but a friend was selling the dual case adapter and skid plate cheap so he got it and already had another transfer case...

I guess he want's to win the slow race? I can already walk faster then his first gear in low range at 2000 RPM...

JeepsAndGuns
02-25-2012, 03:14 AM
IDK 5.13 with 35's is still a bit much with a v8 and that transmission. I use this site to compare crawl ratios and final drive ratios www.grimmjeeper.com/gears.html (http://www.grimmjeeper.com/gears.html) It is very useful since it allows you to compare two different ratios side by side.

IDK, I think 5.13's will be about perfect for what I want. With those gears I will still have plenty of pulling power, awesome low range/crawling ability, and can take advantage of the overdrive 5th.
I too use that caculator, it puts me at about 2500 rpm at 70 mph in 5th with this setup. Thats about perfect.

EagleMark
02-25-2012, 05:30 AM
Couple more points you may alreay know... 5:13 gears will spin the driveshaft about 25% faster then 4:11, at 70 that is fast! CV joints and perfect driveline angles with lift at ride height will be critical!

Choose of tire will also be a factor. Tiller tires put majority of weight further from center point and further from rim where balence weights go. Goodyear Wranglers are an excellent 70 MPH tire but just OK off road. Super Swampers are excellent off road but poor choice for 70 MPH! Not only are they lope sided heavy most are not round. Many come with 4 to 8 once patches in tire to begin with. One guy went to an old school truck stop that still spun tires to true round and lost 1/4 inch tread on one side of each tire to make it round. My Super Swamper Iroks were incredible off road in all conditions, but had 16 onces of Dyna Beads in each tire and still shook at 65, tires were 1/4 to 1/2 inch out of round...

sfara002
09-02-2016, 09:40 AM
Gentlemen,

I feel I am in the presence of EFI legends. I have read countless threads about the 7747 to 7427 swap taking meticulous notes. I assembled a wire harness to make moving back and forth a 15 minute job and double checked the harness twice with a multimeter. I followed Dave's instructions from the CK5 website and Fast's from TGO to apply this to my 91 Full Size 5.7 Jimmy. I installed the 3.9K knock sensor and bypassed the ESC. I got the truck to turn over and start but barely ran, I am talking 300-400 RPM bad. I managed to capture a few seconds of data logging with tuner pro. Looks like it flagged the Knock Sensor but I have no idea why. Any experts willing to take a look at the data? I am stumped on this one. I have good resistance with a multimeter from the old ESC back to the battery ground. I pinned B7 to B15 with zero resistance. I will check the resistance from the wire harness at the pcm to ground in the morning but it should be ok since it runs just fine with the 7747 and 100k knock sensor just fine with no fault codes. It is just frustrating thinking everything is right and things still don't turn out the way you expected.

sfara002
09-02-2016, 11:27 PM
Alright I found the problem! My harness I build with the 7747 pigtail and ecm connector made a poor connection. I cleaned this up now have a functioning truck and pcm. If anyone is going to to make this pigtail just make sure the pins seat in deep enough in the pigtail on the 7747 side. If I were going to do this again I would just unpin the wires from the wire harness and repin on the 7427 plug, the harness has been more of a headache than what it has been worth.

Steve