TBI conversion on a Ford 400 - need help getting it to run

[Dr_Grip]

Hi guys,
complete and total newbie here. I am trying to get a homebrew GM TBI setup running on my Ford 400 and it seems like I hit a wall by now. I really appreciate some help from you guys.

So, what has been done so far?
-I got a TBI system from a 1990 5.7 K-Series truck (7747 ECM).
-Mounted it on the engine's Edelbrock Performer intake
-A Ford DuraSpark II dizzy is connected to a brand-new HEI module (getting a perfect spark at the right time since putting the wires the right way 'round :D )
-Fuel pump's an Airtex E8094
-New coolant temp sensor, IAC, O2 and MAP sensor are fitted
-I did not fit a VSS
-Tested the TPS, it's good.
-I used TunerPro to set the BPW to 161.5 to match the displacement and disabled the EGR (based on the ARHT bin)


Sooo, what happens so far is that the engine starts up nice after a bit of cranking, idle's a bit high at 800-ish (but as I did not set base idle yet and the park/neutral switch isn't connected, that's not too much of a problem, I think).

When I try to build up revs slowly, the engine will hold any given speed (1500, 2000, 2500rpm, etc) only for a few seconds before losing revs (massively leaning out?). Furthermore, suddenly stepping on the throttle leads to violent backfires through the intake. The ECU is not throwing any codes. Any ideas what might cause this?

Once running, fuel pressure sits at .9 bar/13 psi, just as it should - but it takes about 10 seconds of cranking to build up fuel pressure at startup. Is that normal or does it indicate a problem with the fuel pressure regulator (most likely unrelated to issue above, but who knows)?

As I said, I am a total newbie when it comes to EFI, so I am at a loss here. Any help is very much appreciated.

[mmigacz]

Do you have the ability to datalog? Posting the log file, and bin would help to determin what is going on.

[Dr_Grip]

Do you have the ability to datalog? Posting the log file, and bin would help to determin what is going on.I attached the bin file. I'll have to solder myself a log cable and get a logfile, I think I'll be able to do that during the course of the week (the workshop's about 20 minutes from my home so it's tough to get some real wrenching time in during the week).

[fastacton]

As far as fuel pressure goes, the regulator is normally pretty reliable provided the pump can keep up and you have a free flowing return line (more important with a high volume pump). You should get full pressure as soon as you turn the key as long as the pump is running (pressure bleeds off as soon as the pump stops). Have you watched the fuel pressure when you're actuating the throttle? It should stay right about 13 psi as long as the pump is capable. If it's dropping, then that could be your problem, but datalogs will help.

[Dr_Grip]

As far as fuel pressure goes, the regulator is normally pretty reliable provided the pump can keep up and you have a free flowing return line (more important with a high volume pump). You should get full pressure as soon as you turn the key as long as the pump is running (pressure bleeds off as soon as the pump stops).As I said, it takes the pump a few seconds to get up to full pressure (the short pump activity burst when turning the ignition on won't do it). I got an in-line gauge installed and you can watch the needle creep up very... very... slooooowly. But...

Have you watched the fuel pressure when you're actuating the throttle? It should stay right about 13 psi as long as the pump is capable. If it's dropping, then that could be your problem, but datalogs will help.We never noticed any drop once the pressure was where it should be. But I'll double-check and try to get some logs... It seems like soldering a serial cable is a piece of cake - now I just got to find an old laptop with a serial port :)

[fastacton]

If the pump can't get it up to pressure immediately, then that might be your problem. At least with the pumps I use, I'm used to an immediate jump to full pressure, and I'd be concerned that any pump that couldn't do that would be able to give good fuel pressure much past idle. What part of Germany are you in? I spent a few years there in the Ansbach and Schweinfurt areas.

[Dr_Grip]

If the pump can't get it up to pressure immediately, then that might be your problem. At least with the pumps I use, I'm used to an immediate jump to full pressure, and I'd be concerned that any pump that couldn't do that would be able to give good fuel pressure much past idle.The Airtex pump (http://www.rockauto.com/catalog/moreinfo.php?pk=59895&jnid=2&jpid=0) is designed for the TBI systems, but maybe I got a bad one. I'll watch the pressure gauge closely and report back asap. How much pressure can the regulator take without getting damaged? I might as well think bigger in case I need a replacement pump...


What part of Germany are you in? I spent a few years there in the Ansbach and Schweinfurt areas.
I live in Berlin now, but I went to college in Würzburg, so I know the Schweinfurt area. A nice part of the country...

[Dr_Grip]

Reporting back - I fixed the fuel pressure problem. The car now runs mostly fine. There's only one and a half issue bugging me.

The half-issue is unstable idle in closed loop, I've seen tons of threads about this here so I guess I can tackle that on my own.

The biggie is the spark advance: I am trying to re-create my stock dizzy's advance map as a first step and the engine starts having ignition problems as soon as the advance crosses 30°. It's clearly rpm-independent: Wherever I set the advance map to cross 30°, the ignition starts having problems, I even blew my muffler with a violent backfire!
First, I thought I might have an arcing problem so I phased my dizzy correctly. Didn't change a thing. So I connected an engine tester and discovered something really weird:

https://www.youtube.com/watch?v=9rCKq8OAH_g

https://www.youtube.com/watch?v=p-J8Se92brU
Yep, somehow, each plug suddenly starts firing twice.

I then moved the P/N wires further away from the coil to rule out any interference from the discharge. Checked the signal with an oscilloscope, it's clean. The oscilloscope also tells me that the coil in fact is triggered two times per plug by the HEI module.
How's that possible? Bad HEI module? Bad ECU? I really need some pointers here...

[fastacton]

I would think it would be the module or distributor issue. The ECU doesn't tell the module how many times to fire, just how much advance is needed (as far as I understand things).

[Dr_Grip]

Thank you for the quick reply, much appreciated!

I would think it would be the module or distributor issue. The ECU doesn't tell the module how many times to fire, just how much advance is needed (as far as I understand things).That's what I think, too.

I've read on another forum that mounting the module too far away from the dizzy can cause issues, as well. What do you think about that?

EDIT: Here's the wiring. Module is located on the passenger side fender.
http://pic.armedcats.net/d/dr/dr_grip/2015/06/20/IMG_20150620_174012.jpg (http://www.armedcats.net/image/view/GMalptZzWU1Mq3eM)

[fastacton]

I've only used HEI style distributors on my Ford builds, so your wiring setup is a bit different than what I'm used to. This is a good link for how things should be wired up(it's for megasquirt, but still applies):
http://www.megamanual.com/ms2/GM_7pinHEI.htm

[Six_Shooter]

So you mounted the ECM on the intake manifold?

If so, stop the show and move the ECM to the interior. The '7747 is not designed for the underhood environment. The moisture, heat, vibration and other fumes/chemicals,/etc will cause you problems in time, if not very shortly.

It seems that the Ford dizzies don't have a solid enough signal to reliably trigger a GM ICM. It works, yes, but not as well as a GM reluctor does. I've seen a few solutions used, adapting a GM dizzy to the Ford, adapting a GM reluctor to a Ford dizzy. There could be an electronic solution as well, to improve the signal, using an amplifier, but a mechanical solution seems to be the best.

Are your wires between the dizzy and the ICM twisted? They should be. IIRC the recommended is 3 to 5 twists per inch. The twists help reduce the possibility of inducted noise interfering with the signal.

[Dr_Grip]

I've only used HEI style distributors on my Ford builds, so your wiring setup is a bit different than what I'm used to. This is a good link for how things should be wired up(it's for megasquirt, but still applies):
http://www.megamanual.com/ms2/GM_7pinHEI.htmThank you for the link - but it's the manual I used anyways :)


So you mounted the ECM on the intake manifold?

If so, stop the show and move the ECM to the interior. The '7747 is not designed for the underhood environment. The moisture, heat, vibration and other fumes/chemicals,/etc will cause you problems in time, if not very shortly.Wait, how did you get this impression? :) Of course I didn't! It is - not ideally, I know - taped to the rear side of the driver's side fender for now. I'll rip the interior out for a rustproofing effort in a few weeks time and will move the ECM below the front bench then.


It seems that the Ford dizzies don't have a solid enough signal to reliably trigger a GM ICM. It works, yes, but not as well as a GM reluctor does. I've seen a few solutions used, adapting a GM dizzy to the Ford, adapting a GM reluctor to a Ford dizzy. There could be an electronic solution as well, to improve the signal, using an amplifier, but a mechanical solution seems to be the best.I'll keep an eye on that, thank you for the heads-up! Right now, my problem seems to be too many triggers, not too few, but it's good to know.


Are your wires between the dizzy and the ICM twisted? They should be. IIRC the recommended is 3 to 5 twists per inch. The twists help reduce the possibility of inducted noise interfering with the signal.They aren't. I guess that's where my problems come from. I'll switch to shielded twisted cables on Tuesday and report back.

[Six_Shooter]

Wait, how did you get this impression? :) Of course I didn't! It is - not ideally, I know - taped to the rear side of the driver's side fender for now. I'll rip the interior out for a rustproofing effort in a few weeks time and will move the ECM below the front bench then.

From this:

Hi guys,
complete and total newbie here. I am trying to get a homebrew GM TBI setup running on my Ford 400 and it seems like I hit a wall by now. I really appreciate some help from you guys.

So, what has been done so far?
-I got a TBI system from a 1990 5.7 K-Series truck (7747 ECM).
-Mounted it on the engine's Edelbrock Performer intake


So then what is mounted on the intake?

Also, move it inside the vehicle, the same things I mentioned earlier still apply, just being mounted under the hood. Also remember to isolate the ECM case from teh chassis ground. Grounding the ECM case to chassis ground has been known to cause ground loops and introduce noise at best, and damage ECMs at worst.



I'll keep an eye on that, thank you for the heads-up! Right now, my problem seems to be too many triggers, not too few, but it's good to know.

The poor triggering of reluctor doesn't mean just too few, it means poor triggering, which can include too many, due to collapsing magnetic fields.

But...



They aren't. I guess that's where my problems come from. I'll switch to shielded twisted cables on Tuesday and report back.

This is where I would start, twist those wires and the triggering caused by the spark plug wires should go away.

Also in the end using a VSS, will help with stable idle and keep the engine from stalling when coming to a stop, among other benefits.

[Dr_Grip]

So then what is mounted on the intake?A GM TBI unit, of course! :D The injector body itself.


Also, move it inside the vehicle, the same things I mentioned earlier still apply, just being mounted under the hood. Also remember to isolate the ECM case from teh chassis ground. Grounding the ECM case to chassis ground has been known to cause ground loops and introduce noise at best, and damage ECMs at worst.Will do.


The poor triggering of reluctor doesn't mean just too few, it means poor triggering, which can include too many, due to collapsing magnetic fields.On to find a GM dizzy donor, then...


This is where I would start, twist those wires and the triggering caused by the spark plug wires should go away.Will do and report back.


Also in the end using a VSS, will help with stable idle and keep the engine from stalling when coming to a stop, among other benefits.Any recommendations on which one to fit?

[Six_Shooter]

Ok, your wording is a bit odd, a "TBI system" is more than just the TBI and with the order of what you listed it sounded like you mounted the ECM on the intake...

I've used the Painless VSS (2000 PPM model) with great success in the past with the '7747. It it screws into the trans, and allows the speedo cable to be screwed on to it. Painless also makes a 4000 PPM model for TPI type ECMs, make sure you get the right one for your application. ;)

IIRC you could get the VSS from Jags That Run for less than getting it through Painless, even though they seem to be the same unit. I believe there was another brand that worked as well, but I don't recall what that brand was off hand.

[fastacton]

I think I'm going on close to 6 months waiting for Jags That Run to come up with a VSS adapter. I've done some looking around and painless is the only other one I've found, but I think it's about $60 more.

[Dr_Grip]

Ok, your wording is a bit odd, a "TBI system" is more than just the TBI and with the order of what you listed it sounded like you mounted the ECM on the intake...Sorry for the confusion, sometimes the fact that I'm not a native speaker shows through. I do my best, but sometimes I fail :)


I've used the painless VSS (2000 PPM model) with great success in the past with the '7747. It it screws into the trans, and allows the speedo cable to be screwed on to it. Painless also makes a 400 PPM model for TPI type ECMs, make sure you get the right one for your application. ;)

IIRC you could get the VSS from Jags That Run for less than getting it through Painless, even though they seem to be the same unit. I believe there was another brand that worked as well, but I don't recall what that brand was off hand.Thank you for the info, I'll check out Painless...

[Dr_Grip]

That didn't go well. I changed the P/N signal wiring to shielded wires and twisted them. I also moved the dizzy ground from the block to the HEI module, just to be on the safe side regarding ground loops. No change, car still does the double-fire thingy at 30-ish degree advance and more...

[ony]

do you have a large dist cap on your engine or a small cap. never done what you are doing just thinking about what might cause the problem. I remember some posts on here about putting gm efi on fords you might do a search of the sight and find some info.

[Dr_Grip]

do you have a large dist cap on your engine or a small cap. never done what you are doing just thinking about what might cause the problem. I remember some posts on here about putting gm efi on fords you might do a search of the sight and find some info.It's a large cap Duraspark II dizzy with the mechanical advance locked up and the vacuum advance remove.
http://thumb.armedcats.net/d/dr/dr_grip/2015/06/20/300/IMG_20150620_181757.jpg (http://www.armedcats.net/image/view/7YBPA3WotQ3SKZwc)
http://thumb.armedcats.net/d/dr/dr_grip/2015/06/20/300/IMG_20150620_181804.jpg (http://www.armedcats.net/image/view/6zPIZsuGxoS9GKnQ)

I did some on-site searching but didn't find any info that would help me with my special problem...

[Six_Shooter]

Yep, now that you show the trigger, those are known to have inconsistent triggering of GM ignition modules. There was a video posted recently where a gen 1 Camaro had an aftermarket dizzy installed with that same trigger had poor idle and low RPM running. Replaced the dizzy with a stock GM unit and everything was perfect.

[Dr_Grip]

Yep, now that you show the trigger, those are known to have inconsistent triggering of GM ignition modules. There was a video posted recently where a gen 1 Camaro had an aftermarket dizzy installed with that same trigger had poor idle and low RPM running. Replaced the dizzy with a stock GM unit and everything was perfect.Do you have a part number for the stock GM trigger?

[Six_Shooter]

I don't and they would be different for different dizzies, and possibly even different years. You will need to find one that will be the easiest to retrofit to your dizzy.

Alternatively, there might be a GM dizzy that will be close to fitting into your block and need to swap shafts around to get everything to work.

[Dr_Grip]

I don't and they would be different for different dizzies, and possibly even different years. You will need to find one that will be the easiest to retrofit to your dizzy.Dang, I am over in Europe, GM V8 dizzies are kinda hard to come by (and expensive!) over here. Well, I'll find a way...

[fastacton]

You could look for a JM6506 distributor by Top Street Performance. That's a GM HEI style distributor that works with your engine. You would still have to lock out the advance and change over to a 7 or 8 pin module, but I've had good luck using TSP distributors on TBI builds. I normally mod them to accept a 7 pin module, but you could also do an external 8 pin setup. There should be some sellers on eBay that will ship internationally.

[Dr_Grip]

You could look for a JM6506 distributor by Top Street Performance. That's a GM HEI style distributor that works with your engine. You would still have to lock out the advance and change over to a 7 or 8 pin module, but I've had good luck using TSP distributors on TBI builds. I normally mod them to accept a 7 pin module, but you could also do an external 8 pin setup. There should be some sellers on eBay that will ship internationally.That's a pretty brilliant idea! Thank you! Is there a manual on how to convert the dizzy to the 7-pin module somewhere on here?

[fastacton]

There's no manual that I know of, but it's pretty straight forward. On the 5 pin side of the module, 2 go to the pickup and the other three (plus a ground) go to the harness. The 2 pin side plugs right in to the distributor. The terminals are all labeled the same regardless of the type of module.

[Dr_Grip]

That sounds like a plan - since changing the HEI module is the only thing I still have on my list, the opportunity to start with a clean slate, basically removing all wiring, the questionable trigger, the HEI module and the ugliest ignition coil in history at once sounds like a good idea. Thank you, will order!

[JeepsAndGuns]

My jeep uses a motorcraft distributor and the exact same pickup. When I first converted, I had ignition issues. Would barley run, backfire, wouldn't rev up. Long story short, after replacing everything in the whole system, I finally replaced the pickup coil with the most expensive one they had at napa and bingo, all the issues when away.
If your pickup is the issue, you might try replacing it with a quality one before you buy a whole distributor.

[Dr_Grip]

My jeep uses a motorcraft distributor and the exact same pickup. When I first converted, I had ignition issues. Would barley run, backfire, wouldn't rev up. Long story short, after replacing everything in the whole system, I finally replaced the pickup coil with the most expensive one they had at napa and bingo, all the issues when away.
If your pickup is the issue, you might try replacing it with a quality one before you buy a whole distributor.The aftermarket for V8 dizzy parts is not exactly stellar in continental Europe. Without a GM donor car, I won't get anything that's not a whole dizzy over here...

[Dr_Grip]

I finally replaced the pickup coil with the most expensive one they had at napa..Do you still know the part number or manufacturer? Then I could try to get my hands on one...

EDIT: The most expensive pickup for my dizzy at RockAuto is this one: Standard Motor Products LX204 (http://www.rockauto.com/catalog/moreinfo.php?pk=49686&cc=1109247&jnid=481&jpid=3).

EDIT2: Here's my fleet:
http://thumb.armedcats.net/d/dr/dr_grip/2015/06/26/300/IMG_20150623_201049.jpg (http://www.armedcats.net/image/view/iTnddCTEJUgS8wIe)

[Six_Shooter]

This is the video I mentioned earlier in this thread. Notice the problematic pick up on the MSD dizzy, which looks exactly like the Ford pick up you have.


https://www.youtube.com/watch?v=T6vKDsYVj1M

More info in this thread: http://www.thirdgen.org/forums/diy-prom/712261-tbi-7749-8d-s_aujp.html

[JeepsAndGuns]

Do you still know the part number or manufacturer? Then I could try to get my hands on one...

Its been so many years ago I honestly can not remember, but looking it up on napa's website, I believe it was their brand called Echlin, and the part number is ECH MP700.
Looking at the pictures on napa, and the pictures on rock auto of the standard motor products, I think they are the same thing. Seems most all of napa's "store brand" parts are simply reboxed parts from other manufactures.

http://www.rockauto.com/catalog/moreinfo.php?pk=49686&cc=1179435&jnid=418&jpid=3
http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Distributor-Stator-Pick-Up-/_/R-ECHMP700_0060469048

I can not guarantee in any way this is your problem, or that a new pickup will fix it. But it is a somewhat low cost part that might be worth trying before dropping the money on a new expensive aftermarket distributor.

[Dr_Grip]

So I got two people with indefinitely more experience than myself here presenting different versions of the same suggestion - either, as Six_Shooter suggests, Ford-style pickups generally are problematic for GM HEI modules and I should try to convert a GM distributor to my car. Or, as JeepsAndGuns suggests, cheap Ford-style pickups are the problem as swapping my Cardone one out for a better brand-name one could do the trick.

Obviously, the latter solution has the appeal of being easier and cheaper to implement. But in my experience, the amount of appeal a possible solution has should not be judged by factors like this. So, what to do?

I think first thing I'll borrow an oscilloscope and get a reading from my pickup coil tomorrow night and post it here...

EDIT: In any case, thanks to all of you for your support and suggestions!

[Dr_Grip]

So, I put a scope to the dizzy signal as promised. Here's how it looks:

https://www.youtube.com/watch?v=mqCJKXFS7kE

https://www.youtube.com/watch?v=G_bVocW5i4o
What do you think, does that look fine?

I got a log from the second run. Sadly, it's on my buddy's computer, I'll upload it as soon as he sends it to me.

[Dr_Grip]

...and here's the log from the second run.

[Dr_Grip]

Any ideas? Anyone? Anything on the oscilloscope that I am missing?

[Dr_Grip]

Ordered one of 'em cheap dizzys from eBay and a brand-name 7-pin module (the 7-pin module has a GM Europe parts number and is available locally). Changing all ignition components except the ECU should at least give me a new set of errors to work with.

[Dr_Grip]

Installed the 7-pin module in the cheap dizzy (http://www.ebay.de/itm/BBF-Ford-351C-429-460-HEI-Ignition-Distributor-Blue-Cap-351M-400M-6506-BLUE/331566289487?_trksid=p3693.c100102.m2452&_trkparms=ao%3D1%26asc%3D20140212121249%26meid%3D3 88c138c41e148759ef20bf9b1864cd9%26pid%3D100102%26) . Fun fact: The "Beru Germany" labeled module is stamped "Made in USA" on the bottom.
http://pic.armedcats.net/d/dr/dr_grip/2015/07/17/IMG_20150717_170426.jpg (http://www.armedcats.net/image/view/IdxQJd7T3ShdGQ6U)

And put the dizzy in the car

https://www.youtube.com/watch?v=DWJNuBKugUE

Works like a charm. I still experienced one violent backfire through the intake on a sudden kickdown, but I'll log and tune a bit and see what that does before worrying now.

[fastacton]

Pretty clean looking install! If the backfire continues and you can't tune it out, it's possible that it's a rotor phasing issue. Skip White is a pretty good seller. We sell the same brand of distributor (and other products), but I guess our volume is too low to be able to compete with their pricing on the more popular stuff like this. We've had very good luck with this brand of distributor with very few failures, so if it works at first, it should keep on working reliably for a good long while.

[Dr_Grip]

If I had known that you work for a dizzy vendor, I'd have supported your employer, but it's good to know that the dizzy is sound! I must confess I was impressed by the build quality of the thing. The only thing that looked questionable was the no-name four-pin HEI module, but I threw that out anyways.

If you look at the pic you can see white markings from me setting the phasing above the seven-pin module. So if I didn't mess that up, the phasing should be fine... Do you think it's possible that the backfire is a coil voltage issue?

[fastacton]

I appreciate the thought! We just don't even carry that part number since Skip White and others have their prices so low. Your phasing looks pretty close to the last one I did, so it might not be the issue, but if you can't tune it out, it'd be something to look at. I'm not sure that coil voltage could cause an issue, someone else might be able to address that. Hopefully you just need some tuning and you'll be good to go!

[Dr_Grip]

The conversion is very driveable by now! As mentioned, dialing back timing sorted out the backfire issue. (http://www.gearhead-efi.com/Fuel-Injection/showthread.php?4775-Ford-400-timing-tables)

I did some first runs with my bin to log data and get the fuel tables sorted. Also dialed the timing back a bit compared to the table linked over 3000rpm at cruise as she felt unhappy. Will do a logged long-distance run and check how the fuel tables do sometime next week. If satisfied, I'll post the bin to
1. Get input from your guys as to how to get more performance out of the setup
and
2. Give other users with a Ford 400 a good starting point.

Thank you all for guiding me in the process!
Some pics:
http://pic.armedcats.net/d/dr/dr_grip/2015/08/07/IMG_20150805_225213.jpg (http://www.armedcats.net/image/view/mSuVvSnOHpE0ZOQZ)
We had to modify the stock air cleaner a bit to get the large cap dizzy to fit.

http://pic.armedcats.net/d/dr/dr_grip/2015/08/07/IMG_20150805_225222.jpg (http://www.armedcats.net/image/view/Ui8VfC4CnQtGNCmQ)
Two relays on the firewall: Ignition-switched +12V to the ECU and the heated o2 sensor, and ECU-switched power to the fuel pump.

http://pic.armedcats.net/d/dr/dr_grip/2015/08/07/IMG_20150805_225233.jpg (http://www.armedcats.net/image/view/aLHkHysQ0DK9KHoQ)
There's 30A in-line fuse in the EFI power supply cable.

The EFI system's wiring harness is routed through the gearbox tunnel into the passenger compartment, where the ECU lives under the front bench. Velcro does a good job mounting it to the carpet.

[Dr_Grip]

Got a backfire on kickdown at 50-ish kph twice. Accelleration is smooth and powerful from a standstill, higher and lower speeds. It seems that there's a very small rpm/engine load bracket where she's not happy yet... I attached to log file and as always am grateful for any input...

Also I am slowly getting there with the fuel tables... still a bit rich, but at least I am almost constantly in the 120s...
http://pic.armedcats.net/d/dr/dr_grip/2015/08/17/blm_history.png (http://www.armedcats.net/image/view/txqJMjQlq70oRbR7)

[Dr_Grip]

I managed to pin down the backfire issue, it seems to have to do with getting out of idle mode at speed - thus, it should be gone once I get my VSS (http://www.gearhead-efi.com/Fuel-Injection/showthread.php?4894-7747-DFCO-without-a-VSS).

[billygraves]

Dr. In my early days (Late 70's early 80's) I heard some news about Ford V-8 fan blades breaking. The Tech next to me at the Olds Dealership explained a co-worker at his last job looked up after an engine rev with a blade sticking out of his forehead. Check for cracks on the Ford belt driven fan blades. If you live in cold climate leave the Thermac enabled. In the summer, disconnect the vac to it. I would run a cold air tube off the air flt to the front. The heat under hood is pretty high. Use a Thermocouple to measure it. (GM target Thermac Carb Air clnr temps are 140 to 150 deg F)

[Dr_Grip]

Getting there with the fuel table...
http://pic.armedcats.net/d/dr/dr_grip/2015/09/27/blm_new.png (http://www.armedcats.net/image/view/8YUotkD4uHomss7D)

I think from here on it makes no sense to continue tuning until I get the VSS.

[Dr_Grip]

VSS is in, hesitation/backfire at slightly above idle RPM stays. Broadband O2 sensor shows her massively leaning out (consistent with backfiring).

I fear that due to the idle speed being "only" 650 on my Ford I am below the RPM level where the 7747 supports AE. Or is that a bullshit theory? As always, I am grateful for suggestions.

[Dr_Grip]

Finally took the plunge and registered TunerPro. It has been a reliable asset during the last year of tuning, it was about time.

[lionelhutz]

I find that hard to believe. AE should work as the throttle is opened, no matter what the rpm is.

When does this backfire occur - at throttle tip-in or something else?

[Dr_Grip]

I find that hard to believe. AE should work as the throttle is opened, no matter what the rpm is.

When does this backfire occur - at throttle tip-in or something else? See here - I tracked it down, finally. (http://www.gearhead-efi.com/Fuel-Injection/showthread.php?5158-7747-on-a-Ford-400-still-not-getting-a-backfire-issue-sorted&p=57083&viewfull=1#post57083)

[Six_Shooter]

I find that hard to believe. AE should work as the throttle is opened, no matter what the rpm is.

When does this backfire occur - at throttle tip-in or something else?

That's not exactly right...

There are tables (in most codes) that will allow for adjustments to AE based on RPM, and sometimes other parameters, so it's possible that AE needs to be adjusted when other changes are made. It's also possible to disable, intentionally or otherwise AE under certain conditions.

[Dr_Grip]

Engine has developed a tendency to sometimes misfire massively - first time it occured, she hardly came out of idle, had no pull at all, after a longer full-throttle stint. I was on my way to change the plugs then anyways and with new plugs, the issue was gone. So I figured - good timing in renewing the plugs.

Now it returned - several cylinders cut out in idle while sitting at a red light. This times, they returned to working order a few seconds later, though.

Got fuel. Compression's good. Plugs are new, plug wires are new. Thus, I ordered a new 7-pin module. It's either that or the coil.

[lionelhutz]

That's not exactly right...

There are tables (in most codes) that will allow for adjustments to AE based on RPM, and sometimes other parameters, so it's possible that AE needs to be adjusted when other changes are made. It's also possible to disable, intentionally or otherwise AE under certain conditions.

Of course you can tune it. I was responding to the theory about the 7747 ECM not supporting AE at low rpms, as in it simply isn't there and hence can't be tuned.

[Dr_Grip]

Pictures! :)
http://pic.armedcats.net/d/dr/dr_grip/2016/05/08/IMG_20160506_130226.jpg
(http://www.armedcats.net/image/view/9XebNnnMkwGvPwek)

http://pic.armedcats.net/d/dr/dr_grip/2016/05/08/IMG_20160506_191403.jpg (http://www.armedcats.net/image/view/d3Nug3V7L65xeiox)

http://pic.armedcats.net/d/dr/dr_grip/2016/05/08/IMG_20160507_194319.jpg (http://www.armedcats.net/image/view/ov1Jn13XN2nxc0d4)

http://pic.armedcats.net/d/dr/dr_grip/2016/05/08/IMG_20160507_180149.jpg (http://www.armedcats.net/image/view/7WqanQmp4EL02oWs)


And times (slow ones)!
http://pic.armedcats.net/d/dr/dr_grip/2016/05/08/IMG_20160507_201429.jpg (http://www.armedcats.net/image/view/45vsaWcxCaFG1L3v)

[Dr_Grip]

My little conversion project made it on Jalopnik! (http://jalopnik.com/what-its-like-to-drive-the-worlds-most-dangerous-track-1785523188)

[400_Fordman]

Have you perchance tuned out the issue you were having since going racing? That jalopnik article is pretty cool! :D