Ecm is not sending a signal to trigger iac

[joegreen]

Hello, I have had a large vacuum leak from the throttle body for a while but since i only drive my truck every month or so i haven't messed with it. Today i went to check it out and it turns out the 1227747 ecm is not sending a signal to control the iac. What could be the problem?

Also I cannot for the life of me get my laptop to connect to the ecm. I did the timing patch and ever since then it just says connecting never connected. I have an older ftdi driver from 2009 that i know works. The aldl cable i built used to work fine. The tx/rx lights do not light up when i am trying to connect.

[Six_Shooter]

It sounds like you might be in limp home mode. Load a non patched bin and post the results.

[joegreen]

i will try that tomorrow

[joegreen]

ok so i put the afcb bin on the chip. So today when trying to get the iac to move i realized that the ground wire (pin a of the aldl port) was not connected to ground. I fixed this but i still get no movement from the iac.

[Six_Shooter]

Can you get data now?

[joegreen]

actually i never checked. I will check that tonight and get back with the results.

[joegreen]

ok, so i am currently checking to see if it connects and nothing. It just says connecting. I can test the cable and it says found and functional.

[JeepsAndGuns]

Does your check engine light work? If it does, what does it do when you turn on the key? Blink twice then stay on, or blink really fast?

[joegreen]

Actually i was never able to get my check engine light to work. I know its simple to hook up but the ecm would not light up the bulb. I tried troubleshooting that for days. I ended up just plugging into the ecm periodically.

[Six_Shooter]

There's a couple red flags popping up then...

If the CEL output is indeed non functional and the IAC outouts are also non-op, then it could be a quad driver issue.

When you tried connecting the CEL, you did have 12V to the other side of the bulb, correct?

[joegreen]

Yes i did have 12 volts on the other side of the bulb and the ecm is just there to ground out the light. I tried hooking up my volt meter in between the positive and the ecm ground and would get the dvom to display the 12 volts but i could not light up the light. I made sure i had the right bulb and what not. I did a bunch of tests but could not get the cel to illuminate but the ecm was sending out a ground signal to ground the bulb so at least i think the ecm is working correctly. I bought this tbi system off of craigslist and took it off of the doner vehicle myself. The guy also had a relatively new remanufactured ecm that he gave to me.

[joegreen]

Hello, just spent the last couple days replacing the upper ball joints/ control arm and lower ball joints on a ford ranger. Anyway any ideas on what to test regarding not being able to connect to the ecm and the ecm not sendibg a signal to the iac? Thanks for everyones input so far.

[fastacton]

It's sounding like you might have a bad ECM. Can you get hold of another one for testing?

[joegreen]

I dont know where to get another one. Could this ecm be bad even though its remanufactured and the truck runs.

[JeepsAndGuns]

Limp home mode will let the engine start and run, but not very good.
From what I remember back when I was running that ecm and accidently got in limp home mode, the IAC just pegged wide open and I was unable to connect to the ecm.

I would go through and check all the basics. Power, grounds, bad/broken connections. And yes, even if a part is new/reman, doesnt mean its good. I have had bad parts straight out of the box from a parts store.

[joegreen]

Ok i will try those things. Right now i have a cold, what a great christmas present. Anyway ill report back in a few days

[joegreen]

Ok, so i made a mistake when testing the pins that power the iac coming from the ecm. Anyway 2 of the pins tested at 11.xx volts and one pin was .60 volts and one was .30 volts. I ohm tested the iac and got around 50 ohms of resistance on both sides. I think the iac is ok. Is thier any way to test it? Shouldn't the ecm be switching voltage to move the iac pintle and not staying steady?

[joegreen]

I have the a and b pins jumped on the aldl and i noticed that if i keep plugging in the iac it energizes and the pintle tries to move backwards a super small amount. I think the iac is ok but the ecm is not telling it to move. Does that sound correct?

I just tried to get the cel to work and i noticed that if i hook up my volt meter it will try to blink out codes but the second i hook up a light bulb while still haveng the dvom hooked up it stops trying to give out the codes. I think that the ecm is not supply a powerfull enough ground to power the lightbulb.

I also cannot get the computer to connect to my laptop. Is thier anything i can test. I am running an older ftdi driver.

[joegreen]

Ok, so i think thier may be a problem on the ecm side of things. I was not sure if the homemade ftdi cable i made worked but i hooked it up to my dads truck and it connected right away. On my truck it just says connecting forever. I am at a loss. I am not going to change my ecm if thier is no problem because i hate changing parts without diagnosis, but if i were ever to what is the best place to get one. Is an auto parts store re manufactured ecm ok? How much does a junk yard usually charge for an old ecm. If i was to get another ecm should i stick with a 1227747 or is thier a cooler better ecm to upgrade to? Thanks

[joegreen]

I was wondering of the ecm body should be grounded, I don't think it does but was just wondering? Still interested in finding out why my pc wont connect to my ecm But it connects fine to my dads. Also I still cannot get the check engine light to work. I have this problem when i am connected to an ecm with tuner pro or winaldl it occasionally gets errors or stops receiving data. I took a video and will post it up soon.

[Six_Shooter]

No, do NOT ground the case of the ECM. I've seen two '7747s blow up that way. Make sure the case is isolated from the chassis ground.

Have you tried a different ECM yet?

[joegreen]

No, I do not have access to any to try. I would have to buy one. Ok certainly will not ground the ecm chassis.

[joegreen]

Here is the video of the connection error. It happened in the beginning of the video but then it stopped. Of course it started again when i shut the camera off. Sorry for the poor quality. https://www.youtube.com/watch?v=Ww5FqrL7xNU&list=UUXV34icrySbg1SLT6OqyD8w

[delcowizzid]

looking at that video the iac is not going to be working with tps at 4.1% throttle is too far open for idle control

[joegreen]

Lol, i thought you guys would spot that. I was still positioning the sensors when i took the video.

[joegreen]

ok so i just found this post mark made http://www.gearhead-efi.com/Fuel-Injection/showthread.php?273-IAC-Testing-procedure and i am going to re check my iac ohms and the power coming from the connector but i am pretty sure my iac tested 50 ohms with the dvom and and connector from the ecm to the iac tested .5, 12, 12, .5 so per the post does that mean my ecm could possible be bad considering the iac will not move and the fact that i cannot hook up my pc to the ecm but i can on other peoples vehicles and the fact that the ecm does not send out enough ground to turn on my cel. The truck does run but i am going back to school soon and i cannot afford 5 mpg on a 40 mile round trip every day. I am trying to get my pc hooked up so i can get some readings.

[joegreen]

Alright to i retested everything and the iac has 50 ohms of resistance when jumping the pins side by side. The connector from the ecm to the iac showed 11 volts on both diagonal pins and .8 volts on the other diagonal pins. When i have the key on the on position and the a and b pins jumped on the aldl connector i can plug the iac connector into the iac and the iac will twitch. If i keep plugging in the iac quickly it will keep twitching. Does that mean the iac is good. Should the ecm be switching or pulsing voltage on the iac connector to move the iac pintle?

[billygraves]

Alright to i retested everything and the iac has 50 ohms of resistance when jumping the pins side by side. The connector from the ecm to the iac showed 11 volts on both diagonal pins and .8 volts on the other diagonal pins. When i have the key on the on position and the a and b pins jumped on the aldl connector i can plug the iac connector into the iac and the iac will twitch. If i keep plugging in the iac quickly it will keep twitching. Does that mean the iac is good. Should the ecm be switching or pulsing voltage on the iac connector to move the iac pintle?
While I worked on vehicles @ GM Tech Center, the Delco boys warned us many times not to connect/disconnect the IAC while the Ign is ON (running or not) They stated it can cause ECM driver damage. But in another case to set the Min Air Rate, the manual has you turn the Ign ON, jump the ALDL Pins A and B, wait 60 seconds (while the IAC was driven to it's "0" spot) and then unplug the IAC. Start the engine and set min Idle spd to xxx RPM. Some had you disconnect the By-Pass, some not.
There is some truth to this as we found later as we plugged away until the pins wore out. The ECM later could not control idle spd.
One car we had would feel like a big misfire as you pressed on the accelerator pedal. We would give it some throttle and then lift a little. I bet it was a dead miss like a split secondary boot. It ended up being the TWO circuits inside the IAC would touch each other and cause this. They revised the service manual to test for Ohm across each IAC Coil.

[joegreen]

So by me plugging in and unplugging the iac while it was powered i could have damaged the iac or/and ecm driver?

[billygraves]

So by me plugging in and unplugging the iac while it was powered i could have damaged the iac or/and ecm driver?

The probability is higher than normal. The IAC or Truck and Bus, was very slow to move the IAC due to a multitude of stalling in the past in other engine cal groups. It does take some time. If you have a scan tool or you can read the data, use the Open Mode not the 10k mode. I never use Back up mode 3.9k. When you exit this back up, the IAC is usually off some. Meaning the ECM thinks it is at 20 counts and it could be at 45 counts at idle.
I would take the IAC out, clean the throttle body IAC bore with carb clnr. Then extract the pintle from the IAC body. Using brake clean I clean out the passage and shake it out. Place the body in the sun or a low heat like a hot intake for a while. Clean the pintle and spring. I use Anti-sieze compound and cover the threads pretty well. I use a tooth pick and push a bit into the IAC body. Add a few drops of oil. Carefully noting the two flats on the screw of the pintle, line them up with the ones in the body. Push and wiggle the pintle until it almost bottoms out. Start and drive over 40 MPH. Some ECMs reset or find home at 35 and some reset at key down. Shut if off and try it again.
Use the ADX or a scan tool to verify the Park Neutral sw is reading Park and drive at the correct shift lever position. False inputs can cause hi commands like A/C on. Look at the Power steering and insure it does not have or have a two prong switch with wires. If you do, unplug it, the P/S pressure Sw and see if the idle lowers.

One last thought. Do you have a scan tool or any tool plugged into the ALDL? If so unplug it. If the ECM sees a 10k resistor on Pins A and B it will go into Diag mode. This sets the idle to 1000 RPM, Advances the Ignition timing 10 degrees and eliminates the closed loop coolant value and timers. This mode is for GM ENd of Line test. Advance timing to check knock sensor and module. If driven it will induce a rough idle and stalling.

[joegreen]

I used to be able to plug into the ecm but one day it stopped allowing me to connect. I do not have a p/n switch so it thinks its in drive all the time which works fine for me. The throttle body has been rebuilt and all the passages are clean and so it the iac. Are the voltages coming from the ecm to the iac supposed to change or should they stay constant? Is there any was for me to power the iac manually to see if it works?

[tayto]

I used to be able to plug into the ecm but one day it stopped allowing me to connect. I do not have a p/n switch so it thinks its in drive all the time which works fine for me. The throttle body has been rebuilt and all the passages are clean and so it the iac. Are the voltages coming from the ecm to the iac supposed to change or should they stay constant? Is there any was for me to power the iac manually to see if it works?
what kind of truck do you have? i had a 64 impala that i was able to use the existing neutral safety switch and a spst bosch relay to tell the ecm if it was in park or drive. let me know i can post the wiring diagram...

[joegreen]

Its a 1978 chevy k20

[joegreen]

I reinstalled windows 7 after putting a ssd into my laptop. Tomorrow i am going to retry to connect to the ecm.

[joegreen]

I have not tried to connect to the ecm yet but i think i will try tonight. It looks like i can get a 1227747 cardone ecm from advance auto for $78 (actually like $90 something but i get my $15 core charge back) shipped. So the only thing keeping me from buying this is i don't want to spend the money if i do not need a new ecm. The things that have me suspecting i need a new ecm.
1. I cannot connect to my ecm but i can connect up to my dads fine.
2. I cannot get the check engine light to work and i have tried everything. I narrowed it down to the ecm not supplying a strong enough ground to light up the cel.
3. The iac does not work and i suspect the ecm may not be sending out the proper signal to move the iac pintle. I can get 11v on two pins and like .8 on the other two but i believe they are supposed to switch to move the stepper motor, idk i might be wrong on that one?
Right now i am getting 4-5 mpg and i cannot see what the heck is going on because i cannot connect to the ecm. What would you do in this situation? Thanks

[JeepsAndGuns]

There are no junkyards around you that might have one for cheap?
It does kinda point to a bad ecm. Its to the point that if it was me, I would be plugging in a knowm good one to see if it worked.

[joegreen]

i do have a junkyard near me that would almost definitely have an ecm. I was just thinking new for the warranty and the fact that it is tested. I suppose once i solder in my chip adapter the warranty goes anyway. I just did not want an ecm with a bunch of old capacitors and whatnot. What is the lifespan of these ecm's? How much do you think a junkyard would charge? I would love to not have to fork out the money for a new ecm.

[JeepsAndGuns]

Every junkyard is different. Best bet is to call them. Also, most (not all) junkyards will give you a few days warrenty. Most around here give you 30 days.

[joegreen]

It looks like i can get a remanufactured 1227747 ecm from advance auto by cardone for $64. That is about as cheap as i can get it. Should i do the deal or see how much a used junkyard one is?

[steveo]

i'd take a working wrecker part over a reman cardone one any day, even if they're the same price.

when cardone finds the failed component, whether it be a seal in a master cylinder or a capacitor in an ecm, they will replace it with the cheapest peice of shit part they can find on alibaba so it passes the tests and they can get it out the door.

just because it's been 'remanufactured' doesn't mean it'll last as long as one from a wrecker...

[joegreen]

ok, good to know. thanks. ill check with my junkyard and see whats up.

[joegreen]

ok, its $50 plus tax for a used ecm from my junkyard. Does that seem like a good price?

[brian617]

Thats what we sell them for here at our salvage yard.

[joegreen]

Cool, thanks. I will pick one up from from the junkyard.

Now i am not certain if i have to remove the ecm from the vehicle or if they already have some removed but when i looked at my dads ecm it was buried behind the glovebox and looked difficult to remove, are their screws i need to remove or does it just pull out? What vehicle will be the easiest to remove this ecm from? Also my ecm is literally sitting in the glovebox because i don't have anywhere to mount it. I might take a look at some of the older chevys and see how they mounted the ecms. Should i look to get an ecm from a vehicle with as little miles as i can find because more miles equals more wear on the ecm or does it not matter? Lastly is there anything i should look for when choosing an ecm such as water spots or burn marks? Thanks guys.

[brian617]

ECM slips out to the left, has a couple steel clips that keep it snug. Nothing to it. Look for one out of a truck with the most glass in it (dry).

[joegreen]

Best news ever. So i went to the junkyard and got an ecm from an 89 chevy. I tried looking up the code on the ecm which is AMUT but could not find anything on it. Anyway the good news is my IAC now works again, I finally have a check engine light, and i can hook up my laptop to the ecm and view everything. YAY

[sturgillbd]

According to BCC lookup, AMUT is a 1987 5.7 liter with manual trans calibration.

[joegreen]

I did not look very close to see if the truck had a manual trans or not I am also pretty sure it was a 1989 new body style with auto transmission but it might have been a manual. The truck was burried in snow and i only had basically that one to choose from. I never opened up the ecm to see what chip was actually in it. The junkyard put paint over the bolts on the ecm so i don't want to take the cover off for a little while in case i need to return it. If the bin is for a manual trans is it ok to run it like that for a little while? Also i thought the IAC was working but it is not. Because the truck is running so much better i assumed it was working. Is thier any value in my old ecm? How much could i sell it for or should i keep it?

[Six_Shooter]

Restricting you from placing the proper PROM in the ECM is counter productive to verifying that the ECM works correctly. Swap the PROM and if there is a problem expoain to them the reasone for the easy to open PROM access plate.

[sturgillbd]

You will not have lockup converter control with that calibration. It may have a different chip in it than what it says on outside of the case. I wouldn't be afraid to run it as is. It would be good to know what chip it actually has in it though. Have you driven it with the ecm you got from the junkyard? If you have odd issues with tcc lockup, disconnect pin A7 from the ecm connector. What happens if you bridge pins A and B on the aldl connector? With the A and B terminal jumped and turn the key on, you should be able to listen to the IAC and hear clicking where the pintle on the IAC should be bottomed out in the passage.

[joegreen]

Restricting you from placing the proper PROM in the ECM is counter productive to verifying that the ECM works correctly. Swap the PROM and if there is a problem expoain to them the reasone for the easy to open PROM access plate.
I can actually just take the whole top cover off the ecm and swap in a chip i have from a 5.7 th400 truck. That way the access cover does not need to come off. Eventually i will take it off i just want to verify the ecm works for a little.

[joegreen]

You will not have lockup converter control with that calibration. It may have a different chip in it than what it says on outside of the case. I wouldn't be afraid to run it as is. It would be good to know what chip it actually has in it though. Have you driven it with the ecm you got from the junkyard? If you have odd issues with tcc lockup, disconnect pin A7 from the ecm connector. What happens if you bridge pins A and B on the aldl connector? With the A and B terminal jumped and turn the key on, you should be able to listen to the IAC and hear clicking where the pintle on the IAC should be bottomed out in the passage.
My truck has a th400 so no lockup converter. I will pop the whole cover off the ecm and see what chip it has in it. I have driven it since i put it in. I noticed it stumbles when taking off when warm but is super precise with the throttle when cold. I think that might be because the iac is not working. Could that be? I bought a new ac delco IAC from amazon that should be here in a few days.

[Six_Shooter]

The calibration is different between auto and manual, and is the reason you have drivability issues. This is the entire purpose of the swappable PROMs.

[joegreen]

The calibration is different between auto and manual, and is the reason you have drivability issues. This is the entire purpose of the swappable PROMs.
ok, tomorrow i will verify what chip is in it currently. I am going to solder in my chip adapter after using this ecm for a while. If the chip thats in it is for a manual the only other chip i have is afbw which is for a 5.7 th400 truck which should be fine for now. Also i took my old ecm apart to unsolder the chip adapter. I tried looking for anything out of the ordinary but everything looked fine.

[joegreen]

ok, so the chip that was in the ecm i bought was AMUT. I wish i had a better look at the truck because i don't think it was a manual. At the time i was just excited to find an ecm in a truck with with a non working motor. Anyway even though the ecm was very dirty on the outside when i got it it was very clean on the inside when i took the cover off. On the remanufactured ecm i have the clear coat on the inside is all pealing and their might be corrosion under the clear coat. So the old ecm i bought is in much better shape visually. I just swapped in my old AFBW chip and the other smaller chip (i forgot what it is called). I plugged in the ecm and the truck fired right up. I am now just waiting on my new delco IAC from amazon. It is amazing how good the truck runs with the new ecm. I had been using the broken ecm since day one so i assumed thats kind of what tbi was like. I hope my fuel mileage goes up from the current 4 mpg. I am sure it will though. Here is a pic of the inside of the new ecm. It was taken with my cell phone so it was not the best pic.

[joegreen]

ok so some things i have noticed since the new ecm. First i noticed that the engine stays cooler. I have a 190 thermostat and before it used to idle around 200, now the thermostat keeps opening and closing to keep it at 190. The exhaust does not burn my eyes anymore. Truck starts almost instantly. i thought my IAC was not working but it turns out is was. I reset the iac and set base idle to 100-125 rpm lower than the minimum in the bin. The bin is at 600 rpm. I also checked my timing with the brown wire unplugged and it was like 6-8* btdc. I put it at zero and that seemed to help. I took it out for a little drive and it still pops through the intake if i open the throttle fast. low to mid range power is up but it has like no guts when floored. It seems to have ok power if i don't lean into the throttle to much but when i do get into it the power goes away. It has a brand new timing chain in it. I took a datalog on my short drive today. when floored i only get to 70% throttle so i will have to see what i can do with the throttle linkage. maybe someone can look at my log and let me know what you think. Its short maybe like 10 min.

[sturgillbd]

I just played back your log file. At idle and low loads on the engine BLM's look pretty good. As soon as you start to put a load on the engine, your BLM's climb higher and higher.At one point I saw the BLM climb over 150. If this is a stock tune, you may have a plugged fuel filter or a fuel pump starting to fail. Have you replaced the fuel filter? If not, replaced the fuel filter and perform another log. You also should measure your fuel pressure to see if it is in spec after replacing the fuel filter.
Brian

[joegreen]

so a high blm indicates a lean condition? Could that equal a power loss? I picked up a inline metal fuel filter at autozone that was for a nissan or something so i am sure it is fine for the low tbi psi. The fuel filter is pretty new like half a year with maybe a thousand miles on it. The fuel pump is the same one that came out of the donor truck. I set fuel pressure a while ago at 14 psi and it seemed to hold steady. Should i check it again? I would hate to have to drop the tank to replace the pump but if thats what needs to be done. what could be causing the backfire through the intake when moving the pedal fast? I need to get my chip adapter soldered in so i can disable some things like the egr and whatnot. Also when the truck is cold it runs awesome. I can spin the tires and it does not backfire through the intake.

[sturgillbd]

High BLM's means lean. Use a gauge and measure fuel pressure when under load to make sure your pressure stays up. Plugged fuel filter can cause the symptoms you describe and fuel pressure may be dropping under load. You are definitely leaning out as the engine load increases. Have you made any adjustments to your VE tables? That high of BLM is about to the limit the ECM can adjust. Play your log file and watch the data. You are shooting for 128 + or minus 5. I would rather it be lower than 128 instead of above. Backfire through intake us usually a sign of a lean condition. Get your BLM's in range first and then you may have to tune Acceleration Enrichment to stop the backfire under quick opening of the throttle.
Brian

[joegreen]

ok sounds good. i will rent a fuel pressure tester from autozone tomorrow and see how it goes. thanks.

[sturgillbd]

While you are working on your vehicle tomorrow, get the number on top of your injectors and post them. I'm also curious as to what injectors you are using. Is this a stock bin you are running or is it modified? Can you post the bin?

[joegreen]

While you are working on your vehicle tomorrow, get the number on top of your injectors and post them. I'm also curious as to what injectors you are using. Is this a stock bin you are running or is it modified? Can you post the bin?
currently i am using the stock AFBW bin. Both injectors are brand new. http://www.autozone.com/fuel-delivery/fuel-injector/gp-sorensen-fuel-injector/chevrolet/k2500-3-4-ton-p-u-4wd/1988/8-cylinders-k-5-7l-tbi/79734_3214_0/.

[joegreen]

I took a data log on my trip home from school to pick up the fuel pressure tester. I also took a log while the fuel pressure tester was hooked up. The fuel pressure stayed at 13 psi and did not drop at idle, cruising, or when floored. I will post up those logs in a little. Also i noticed when i went to go out for my test drive the IAC counts went to like 145 and the truck idled around 500-550 rpms.

[sturgillbd]

Ok , your newest log shows lean at cruise speed etc. I also notice two error codes set. First is error 32 (EGR). I assume you do not have egr hooked up. The second error is 42. Have you cleared codes since disconnecting the bypass wire and setting the timing? Did you hook the bypass wire back up? EGR can be turned off in the bin. Base ignition timing needs to be set at 0 degrees with bypass wire disconnected. Shut engine off and reconnect bypass wire. Disconnect battery terminal for a few mins to clear codes. Drive vehicle again and make sure error 42 doesn't get set.

[joegreen]

i set timing to zero and everything but i never disconnected the battery to clear the codes. I will do that end verify that error 42 does not come back. If error 42 does appear what is usually the cause?

[sturgillbd]

Looked at history tables and the averages do not look as bad as just watching the data as it is being played. Here are some screen shots of BLM in the history tables populated with your longer datalog. Get your error codes cleared up and start tuning using the spreadsheet.

[joegreen]

I was just reviewing my drive with fuel pressure log and i noticed that voltage goes to .1v and shift position indicates park. Another problem i have always had is when i am in tuner pro and connected to the ecm where it says connected in dark blue that almost constantly flashes error in red. The the left where it says how may times an error pops up mine goes into the thousands on a drive. If you watch the time closely on my data logs you can see that like 2-5 seconds go buy before new data comes in. Is this a potential problem. When i look at other peoples data logs they are much more fluid and uniform in thier data delivery. Also on my drive home i noticed the battery voltage drops and the peaks and while this happens the blm drops?

[sturgillbd]

You may have latency issues with your cable. Have you adjusted your latency timer in device manager of your laptop? Here is info from Moates:

Open up your Windows Control Panel, under ‘System’ and ‘Hardware’ and ‘Device Manager’ under ‘Ports’. Find the USB Serial Port, and go to the Port Settings tab. Go to the Advanced button, and make sure the COM port setting is either COM3 or COM4. Set the latency to 1. If having connection issues, you might try a latency of 5. Once settings are applied, hit OK and close out all Control panel stuff. Keep in mind that this will be valid and ‘keep’ for the particular USB port you are plugged into for next time. If you plug into a different USB port you’ll need to do this again for that one.

You may also lower the receive buffer size.

Hope this helps
Brian

[joegreen]

This is so frustrating. I cannot get tuner pro to show a solid connected. I tried all my usb terminals, 2 different cables, tried adjusting latency all over and the same with the recieve buffer size. Nothing works.

[sturgillbd]

Reset your your latency settings and buffer sizes back to default. Try to connect to your father's truck and see if you get good data from it. If it connects to it with no errors, then you need to look for ground issues or the harness routed too close to plug wires etc. Does your laptop connect to your truck with key on and engine not running with no errors? If so you may be getting noise induced into the harness from the plug wires etc. I have two cables I use. One is a homemade interface that uses a 9 pin serial and I normally use it on the 160 baud systems. The other is a USB to Serial TTL cable. On it, It twisted RX and TX together and soldered it to a pin. I also soldered a pin to the ground wire on the cable. I just stick the pins into the aldl connector's A and M terminals. A is ground and M is serial data on the 8192 baud systems I have used. I will set up a 160 baud ECM tonight and try the FTDI cable on it and see if I have any issues with it.

[joegreen]

I cannot connect to my dads truck because he is a state away. i deleted tunerpro 5 and downloaded tp4 after reading about other people having connection issues. I now get a steady connected in blue with no errors. yaay but i cant get the dash to display data and the data i can find goes crazy. Like im going 0mph then im going 128 mph, every value jumps all over the place.

[joegreen]

I redownloaded tunerpro 5 and i still get errors with the key on but the engine not running.

[sturgillbd]

Which adx file are you using?

[joegreen]

I am using

[joegreen]

I really appreciate all your help sturgillbd and to everyone else who has helped out.

[sturgillbd]

I do not have a 7747 ecm here but I do have an 8746 which is a lot like a 7747 but uses an IAT sensor and is a different mask. I am now in the process of setting up a bench test for it using a FTDI usb cable. I will pick up a 7747 from a friend either tomorrow eve or Sunday morning and do further tests with it. I use TPv5 and I am going to try to reproduce the errors. I will let you know what I find tonight on the 8746.

Brian

[sturgillbd]

Well, I just tested connecting to the ecm. It connected up instantly with no errors. I have no sensors connected. I just powered the ecm and hooked up the cable to serial data and ground. Screenshot was taken after about 3 minutes of being powered on. One thing that comes back to mind is you said your aldl A terminal wasn't connected to ground at one point. Where did you connect it to ground? If I were you, I would put a ring terminal on a length of wire and connect one end to the same ground on the engine block as your ecm ground and the other end back to your aldl A terminal.
I dont run the Windows OS natively. All of my PC's and even my firewall/router run Linux. I load windows in a Virtual machine to run Tunerpro. I set up a laptop with XP and Tunerpro for the same guy that I'm going to borrow the 7747 ECM from. I will grab his laptop also when I get the ECM. Will be tomorrow night or Sunday before I get to test the 7747. Try the ground idea first and let us know the results.

[joegreen]

so you are saying i should run a length of wire and have pin a on one side and the other side will be connected to where the ecm ground is connected on the engine. Then i will use that new ground i ran as the ground for my aldl cable.

[sturgillbd]

Yes.

[joegreen]

when i did connect to my dads ecm a while ago i did get some errors but the data was consistent and i didn't get crazy almost constant errors like i am now. I dont know if i mentioned this but when the engine is stone cold it has really good throttle response and it does not pop through the intake. Its once it starts to warm up the engine gets worse and worse where i have to open the throttle slowly to not cause a bog or backfire through the intake. I still have the fuel pressure tester hooked up and i still have a constant 13 psi after the fuel filter. Also not sure if it matters but when i rebuilt my throttle body i shaved off the rings that went around the top of the venturis for the throttle blades and i think i might have 2 gaskets stacked to raise up the whole injector assembly but i might not. i will have to double check.

[sturgillbd]

That sounds like it is lean in closed loop. You can unplug the coolant temp sensor and the ecm will think it is cold too and really richen up the mixture. Work on one issue at a time. Lets try to get clean data first. After you get clean data, then you can datalog and run the data through the spreadsheets.

[joegreen]

Some good news. I ran a brand new ground wire to the same bolt everything else is grounded to and i only got 1 error in a minute of time while moving the throttle back and forth with the engine off. I also changed my latency to 1ms. When i start the engine i get a whole bunch of errors again. Im going to go move and secure some wires and see what happens.

[joegreen]

Latency at 1ms and receive bytes set to 1024 and i haven't gotten one error in a couple minutes of playing around with the key on engine off and the data flows nicely. I tried moving all the wires i could away from the spark plug wires but i still get a bunch of errors when i start the truck.

[sturgillbd]

That is still progress. Make sure you have the ground strap from the engine to the body connected and the connection is clean. Body, frame, and all electrical grounds need to be clean and actually installed. You may have to lower your buffer size on your port. I did some reading last night on problems people were having and they increased latency time and lowered buffer size. Also may try setting flow control to none on the usb serial port in windows. It is going to take some effort but you will get it figured out.

[joegreen]

I have a ground from the battery to body, battery to motor and motor to body. I tried adjusting latency and buffer size all over the place and nothing made a difference while running. I have flow control set to none. I ran across something in my internet search but i dont know how to do this. http://www.thirdgen.org/forums/diy-prom/591762-tuner-pro-rt-da.html

[sturgillbd]

I tested a WinXP laptop and a FTDI cable to a TBI conversion Jeep today, We put TBI on this Jeep in 1995. I put his original EPROM back in it and the BCC is ASDX. I started the jeep and connected the laptop to it and it ran for approximated 20 minutes. I had three errors during the time it was connected. It was 17 degrees here today and it took about 10 minutes for the engine to come up to operating temp. If you are getting clean data with key on and engine off but errors when it is running, you are getting noise induced into the harness from the ignition system or the charging system. The three errors I got were possibly because the jeep I tested on is getting really rusty and the grounds haven't been cleaned since we installed the TBI system on it. As for the thirdgen link you referenced, that is for a different type of ECM that uses two way communication for data. The 7747 ECM's just puke a packet of data out about every 1.2 seconds on the serial line and you don't have to send anything to it for it to start. See http://lukeskaff.com/?page_id=305 and look for the section on 160 baud. Do you have an inverter running your laptop when datalogging? Others have had issues with inverters creating noise causing data errors when connected to the ALDL. I'm attaching a couple of pictures I took with my phone. The pic of the cable end connected to the aldl connector will show the quick and dirty way I plugged in and how rough this old jeep is. I forgot my cable and we haven't soldered any pins onto the end of his. This could have been a couple of the errors :)

Brian

Edit: There is an error on the page of which I sent the link. He states serial data is on Pin A and it is actually on Pin E. Pin A is the ECM ground.

[joegreen]

I have my aldl end basically missing and i just have my ftdi adapter soldered right to the harness so i wouldnt/shouldnt have a bad connection to the ecm. I haven't neatened up my harness yet. I was waiting until i got the truck running good so incase i have a problem i can get to the wires quickly. Right now its a somewhat orderly rats nest of wires. if i have tuner pro connected with the key on not getting errors i will get errors the split second i turn the key to start it. What wires in the harness matter as far as noise being introduced into them that would cause the ecm to display errors? As far as ignition noise do i just need to keep the harness wires away from the spark plug wires? How would the charging system introduce noise? I took apart my delco 10si alternator a couple months ago and cleaned it up nice. I was going to do a rebuild but it was in good shape. Could the capacitor in the alternator be bad? The laptop is not running off an inverter. Just its own battery. I am going to post up picks of my grounds and harness so you can see what i am working with. Hope things don't look to gnarly. The first pic is of the homemade aldl soldered to the harness, then the battery to body ground (looks rusty but its not), then battery to engine ground, then engine to body ground, the rest is of the harness. The yellow wire is the new ground i ran.

[sturgillbd]

It looks as though your whole harness is basically laying on your plug wires. You need to bundle the wires up at least with some zip ties and get them a few inches away from the plug wires. When the harness wires lay parallel with the plug wires, a voltage is induced into the harness. Your ecm is seeing a spike each time a plug fires. If you get them away from the plug wires, you have a good chance of cleaning up your data you see on TunerPro. I would also take all of the grounds loose and take a wire wheel on a drill and clean the steel until it is shiny metal. I would put dielectric grease or NOALOX on the terminals and the steel before putting the bolts back in to secure them. This will slow the corrosion down and you will have a much better electrical connection. I believe your main issue is the harness is too close to the plug wires. Normally the harness is bundled in loom and comes from firewall area down the passenger side of the intake. I'll post a pic of how my harness is routed.

Brian

[joegreen]

the pictures dont do it justice but the harness wires are a good 2 inches from the plug wires. But tomorrow i am going to zip tie all the wires and get everything as far away from the plug wires as i can. thanks

[sturgillbd]

This was taken last Sept when I was cleaning up the engine harness. Picture isn't the greatest and I didn't have any wire management on my plug wires either. You will get the idea of how I routed the harness though.

[joegreen]

that is nice. Mine looks like a pile of turds. Kind of makes it hard to find where their is interference. i do have all the plastic wire wrapping i was just waiting until the weather got warmer. right now its -9f out and i dont have a heated garage.

[Six_Shooter]

Most of the time 2" is not enough distance between plug wires and EFI harness.

[sturgillbd]

I don't have a heated garage either. That is why my jeep project is on hold until spring. I have been doing the work under a metal carport. I had wires everywhere also at first. I was just trying to show you a way to route the wires to minimize interference. Here is what my dash wiring looks like at the moment. It takes time to sort this stuff out when you do the conversions. This is a 1953 Willys M38A1 I have been working on for 3 years. EFI harness is out of a 1995 fullsize Chevy Blazer. The fusebox, steering column and associated wiring is from a 1993 S10 blazer. The second pic shows some of the carport I have been working under. No sides on it. Just a roof...Thats all. I was not trying to put down your work or your wiring. I was just trying to help you get your problem solved. You know it runs and the sensors work. You can start bundling the harness back together and routing it in a way that minimizes it's proximity to the ignition system. I always have a concern with grounds. That is why I mentioned cleaning them up with a wire wheel. I know you are frustrated with all the issues you have had. You are making progress though.

[joegreen]

Some strange observations. I disconnected power to the coil so i could rule out spark plug wire interference. I also disconnected the alternator. Here is the weird part. I had tuner pro connected without any errors and when i went to turn over the motor the starter did not engage the flywheel but i still started getting errors in my data. So with only the starter spinning i was getting errors. Does that point to anything?

[fastacton]

I would verify all of your power and ground connections, but I don't think I'd worry too much about anything until the harness is taped, loomed and clamped where you want it. Or at least zip tie it into bundles about where it should be. I'm fairly sure that your starter is putting out some EMI that could cause errors, but those would go away once the engine is running.

sturgillbd, your M-38A1 body looks much nicer than mine! It'll be a nice toy once it's finished!

[sturgillbd]

The starter has brushes and a commutator. It is a high current DC motor. When the starter turns, there are sparks at the brushes and a starter makes lots of noise into the electrical system. That is normal. Also when the starter turns, it usually pulls the battery voltage down somewhat, especially when turning over an engine. I get data errors also when connected to the ecm with TunerPro and starting a vehicle. Normally you start looking at data with the engine running. If you bundle the harness and get it away from the ignition system, I believe your data will be much better. I also assume you have the three grounds from the ecm connected to the engine ground. The three grounds are on pins A12, D1 and D6. http://www.gearhead-efi.com/Fuel-Injection/attachment.php?attachmentid=1935&d=1331599707

[joegreen]

I guess finishing up the harness is going to be put on hold for now due to the fact that its freaking cold outside and i have next to no time with school. As a side note i did unplug the CTS when the engine warmed up and the backfire through the intake went away and the throttle response was so fast and precise. I guess that basically points to a fueling issue. Seeing as i dont have much time left to exchange the ecm at the junk yard are we pretty sure this ecm is good? I get good data with key on, the CEL now works, and my IAC now works, and it does not idle as rough anymore. Is their a definitive way to test the ecm? I just want to make sure because tomorrow i thought i might solder in my chip adapter to the new ecm so i can turn off the EGR and stuff. Does that sound like a good idea?

[sturgillbd]

I believe your ecm is good. The engine will probably run better also after the harness gets bundled and away from ignition system. The noise will affect the fuel and spark because it is not a clean signal coming from the sensors such as O2, tps, cts etc. Before you bundle it up, make sure all of the grounds are there that I mentioned in the previous post. Clean your grounds and put something on them to prevent corrosion. That will save you problems later on down the road. It is supposed to get colder the rest of the week here. We have about 10" of snow on the ground from the snow storm today. It will hang around for a few days because lows are supposed to be in the single digits and highs in the teens to around 20. Winter has finally arrived here. You guys up north have been hammered this winter.

[joegreen]

where i am the snow is not to bad and i am pretty happy it keeps coming on a monday because i have only had one monday of school since january. the rest of the mondays have been canceled. Tomorrow a will solder in my chip adapter. I bought a solder sucker from amazon and they made a mistake and sent me two, yay. I looked up solder sucker mods and today i added a silicone fuel line from my nitro rc truck to the end of the solder sucker so i can get a good seal with the board and really pull the solder off. Ill see how it works tomorrow.

[joegreen]

I am having some problems. I soldered in my chip adapter and burnt a ASDU chip. Anyway The truck runs but the cel flashes telling me i have a bad ecm. The Iac stopped working. I am going to try and reseat my prom.

[joegreen]

Ok so the truck is running off of that smaller chip to the side of the prom. I took the prom out and it ran the same. I think i did a good job at soldering in the adapter. Here are some pics of the install. am i not soldering it in the right way? It runs exactly like it used to which leads me to believe the old ecm was also running of the secondary chip.

[Six_Shooter]

I think we found your problem...

That ZIF socket is not an adapter.

The G2 adapter actually sets hardware addressing of the chip so that the correct section (addresses) of the chip are read.

A simple work around is to short pins 1,2,3, 28 and 27 or it's possibly 1,2, 28, 27, 26. I don't recall off hand but there is information on it on this forum and through Google search for 24 to 28 pin adpater in a C3 ECM.

Here's what you need to use a 28 pin EEPROM in a C3 ECM: https://www.moates.net/g2-memory-adapter-060-leg-spacing-p-36.html?cPath=64

[joegreen]

i wish it was that easy. I did the workaround to short out the pins. I posted the pics in a tread a while back but i cant find it.

[sturgillbd]

Check continuity between all bridged pins 5 pins with an ohmmeter. Also, make sure you programmed the chip with the proper offset. In flash and burn program or in tunerpro set

Buffer Start -> End Chip Start -> End
000000 -> 000FFF 00F000 -> 00FFFF

http://support.moates.net/programming-chips-using-offsets/

[Six_Shooter]

i wish it was that easy. I did the workaround to short out the pins. I posted the pics in a tread a while back but i cant find it.

But it is that easy, I've done it several times. Though I usually install a 24 pin DIP socket directly to the ECM daughter board, then use a modified 28 pin DIP socket stacked on top. I don't usually use a ZIF socket but if I do, I stack it on top of the modified 28 pin DIP socket.

I know other people have soldered to the pins directly on the EEPROM, but I don't like this idea, it just doesn't feel safe to me, even though others have not had an issue with it. I don't recall if the offsets need to be left at 00000, or changed as you would normally do with a non modified EEPROM.

[joegreen]

I feel like the offset may be my problem. I thought tuner pro set offset automatically. I am using a 27sf512 chip. I am a little confused on how you wrote the offset. Here is what i currently have in tp.

[sturgillbd]

Buffer Start 00000 Buffer End 000FFF

Chip Start 00F000 Chip End 00FFFF

[sturgillbd]

Refresh the page. I tabbed and hit enter and it saved post before I was finished typing it. I edited the post

[sturgillbd]

When you tie the last 4 address pins high on the chip, It forces the chip to address the last 4k of the 64k That way the chip appears the same as a 2732 to the ECM.

[joegreen]

I checked continuity on the 5 pins and they have good continuity. I tried changing the chip adressing and when i change the end buffer address the end chip address changes. I cant make them the same.

[sturgillbd]

Set the other one first. If you still have trouble , download the Flash N Burn standalone utility from Moates. http://support.moates.net/flash-n-burn/

[joegreen]

The flash and burn does the same thing. I can have the buffer and chip end address 00FFFF when the chip start adress is all zeroes but when i change the chip start address the chip and buffer ends cant match

[Six_Shooter]

Yeah, you might either have to get a programmer where you can easily set the offset addressing or get/make a proper adapter.

The forced offset addressing of TP RT/ F n' B might be whats causing you issues.

[joegreen]

Ok everyone i got it. there were a couple confusions. First on my part i was not even programming the chip correctly. First i found this post from mark http://www.gearhead-efi.com/Fuel-Injection/showthread.php?1477-Reading-Stock-GM-Chips-Burn-1-Burn-2-AutoProm-TunerPro-Flash-and-Burn then i followed the link to http://support.moates.net/programming-chips-using-offsets/. I followed moates step by step instructions. I did not know you had to load the file to the buffer. I thought that it just burned the bin you had open in tuner pro. Also no offence sturgillbd but you gave me the wrong end buffer. You included one to many F's. This makes me wonder if the old ecm was actually bad because it turns out i dont think i was actually burning anything to my chips (oh man). Although the CEL did not work before and now it does so yay.

[sturgillbd]

I apologize and no offense taken. If you will look at my first post on to you on programming using offsets ( http://www.gearhead-efi.com/Fuel-Injection/showthread.php?3987-Ecm-is-not-sending-a-signal-to-trigger-iac&p=48191&viewfull=1#post48191 ), You would see I gave you the proper address then. I made a typo on the second attempt in trying to show the proper offset. I will try to go back and edit it but if I cannot, will one of the moderators please edit it so there is not bad info floating around?
Thanks,
Brian

[joegreen]

Well now that everything is sorted out my next step is to finish up with the harness. Then hopefully get some good data. Then on to tuning. Thanks everyone

[joegreen]

I drove my truck to school today 40 miles round trip with the ASDU chip with the egr turned off and it did not do the best. Friday i am going on a trip to a friends house to help him move furniture. His house is a few hours away and my truck does not work well when taking off from a stop or from slow speeds. When you press the gas it stumbles and and if you press it to far it pops through the intake and dies. He is located near the city and its alot of stop and go/get out of my way type traffic. When i unplugged my CTS the truck ran a lot better which points to a lean afr. I hope it does not seem like i am looking for an instant fix it all, I am just looking for a modified bin that maybe someone has that will add some more fuel. The truck has better take off running off the secondary chip. I am not asking anyone to modify a bin, just post up a premade bin if you have one lying around on your pc so i can try it. Thanks guys.

[joegreen]

Alright so i installed the new harness and have it mostly finished. I connected my laptop to the computer so i could see if i get any errors before i tape up the harness. The good news is the harness works the bad news is I am still getting almost constant errors. I tried all different sorts of latency settings and recieve size settings and nothing stopped or slowed down the errors. I can still connect error free when the truck is not running.

[joegreen]

I am trying to get tuner pro rt v4 to work and i can get it to where it says that it is connected but it connects the instant i press the connect button and it does not actually show any real data. I dont think that it is actually connected. How can i get tp v4 to connect properly.

[joegreen]

i took the belt off of the alternator to rule that out as far as interference. When i connected tunerpro i still get errors. Do you think i might need new spark plug wires. Ill have to check and see what i have on thier now.

[joegreen]

I did an ohms test between the aldl ground at the aldl port and the ecm case. I read the post below by six_shooter

Results: engine off = .1 ohms resistance
key in on position = 12.4 ohms resistance
engine running = 5.6 ohms resistance

Could be a noise issue.

Grab a DMM and check for ground at the ALDL connector, referenced to the battery and the ECM. Do this with the engine off and running, and look for a change there should not be or very minimally, like a shift of only a couple ohms if any. You can also use the voltage setting, and this should be at zero and remain at zero in any instance, if there is voltage shown on the ground at the ALDL when using either the battery negative or ECM (case is fine) then you have an issue with the ground lead at the ALDL, most likely.

Also while you're there, check the data line, and make sure that it's 5V at KOEO, and also at KOER, if the voltage drops off at KOER, then you may have an issue with the ECM, or possibly the grounding of the ECM to the engine block/heads.

[joegreen]

Good news. The stupid DA data error problem that I have been chasing with tuner pro has finally been solved. It turned out to be my usb aldl cable. I tried a serial port cable from sturgillbd and it worked flawlessly. I did not get a single error running my truck for 7 minutes. Now i can finish putting my truck together and get some good data. I am excited to see what fuel injection is really like.