Runs worse as it learns....

[mikeames]

Hello,

I've got a complicated system with a few problems I'm trying to work out. By complicated I mean I'm running a GM based TBI system from Affordable Fuel Injection (they have been almost zero help) on a 1984 Dodge W350 Crew cab with a 360 that has been stroked out to a 410 stroker motor. It can make a lot os HP and torque if it runs right. I have a 454 TB and for sensors I have an IAC, MAP, Temp, TPS. No knock sensor. For ignition I'm using a stock MOPAR distributor (magnetic) with the advance welded and a GM ICU. I've checked it thoroughly for vacuum leaks and I get no trouble codes.

I'm finding my GM TBI system gets worse over a period of a few days... If I pull power to the ECM then reinstall the fuse it runs pretty good for a few days and the slowly gets worse and worse. I get what feels like a lean miss and eventually it backfires on acceleration. if I reset the ECM again it gets better for a few days and then slowly come back to the poor running.

I also have problem with spark advance. If I set my base timing to zero degrees (unplugging the wire) I get lots of pinging right off the bat without even giving wide open throttle...really bad.So I've been running it with the base timing set to about 8 degrees retarded and although the pinging issue is nearly gone, I've also lost most of my power and the mileage sucks. I've tried swapping the ICU with no change. I also pulled the distributor and made sure everything was still welded together (the advance is welded) and nothing was sloppy or loose.

I do not know what my injectors are and the folks at Affordable have no idea what they sold me either (jerks), BUT I took them to a place in Gladstone and had the guy flow test them. He said they are both even and have a nice pattern, BUT they are huge injectors...they tested at 180 at every pressure he put through them. I am running 26 psi fuel pressure (that's the way it was setup when it came).

I hate simply swapping parts....so I'm trying to get some advice on what my problems might be. I believe I have a couple of them at least.

Any thoughts??

[billygraves]

........

[lionelhutz]

I didn't see the ECM service part number in the list of info billygraves asked for so provide that too.

[mikeames]

The engine was built at the same time the TBI system was added.
Forged pistons, 10:1 compression (I always run premium), Cam is a custom grind with Exh lift 444, Centerline 114, Duration 214, Intake Lift 443, Centerline 106, Duration 214, Cam timing is 105 degree intake, Rockers are OEM, Stock Cast iron intake with an adapter plate to attach the TBI unit.
ICM is a stock GM (currently an Autozone part), mounted to a heat sink with heat transfer paste (aluminum plate) mounted to the inner fender well away from heat and grounded well. Distance from ICM to coil by wire is probably three feet at max. The pickup wires from the distributor to the ICM have no shielding.
Os sensor is a 3-wire, heated unit, I have no idea what the brand is but told (by AFI) that if it needs to be replaced that a unit off of a 1995 Chevy K2500 w/ 350 will fit. The O2 sensor is mounted in a bung on the passenger side header collector.
Wiring harness custom built for the app by Affordable Fuel injection which supplied the whole kit and was supposed to custom burn the chip for the application.
I'm not sure about the ECM ground questions...I'm an electrician, I try to make sure everything is grounded to clean bare metal. The block and the body and frame are all bonded together well.
I have both ALDL and TunerPro software. I can record data easily with the ALDL software, but I haven't figured out the TunerPro software quite yet.
The injectors don't appear to leak.
The system did not come with a knock sensor, AFI knows it does not have a knock sensor and I assume they programmed the chip accordingly.
No idea if the EECM is a reman. I only know that it did not look new and I've swapped the EPROM several times with new burns from AFI.

I think that answers most of your questions...let me know if I missed anything.

[mikeames]

Also, the truck has a manual transmission.

[mikeames]

The ECM is a 1227747...is that what you mean?

[steveo]

a few days is a long time; but if you unplug the o2 sensor, does it continue to run poorly for a few days?

who tuned this thing?

why are you still running a botched timing map?

sounds like maybe just a bad tune...

[mikeames]

a few days is a long time; but if you unplug the o2 sensor, does it continue to run poorly for a few days?

who tuned this thing?

why are you still running a botched timing map?

sounds like maybe just a bad tune...

I have not tried unplugging the O2 sensor...although it is running closed loop.

The Affordable Fuel Injection guys tuned it several times....but they couldn't seem to get it right and stopped providing me any service. I gave them every bit of the info they asked for before even ordering the kit and provided multiple data collection files exactly as they requested, but apparently they were too busy to provide a finshed product. I would not ever recommend them to anyone ever.

I strongly suspect my timing match is botched, but I don't know how to fix it.

I consulted a guy here locally that could burn the chip...but he didn't seem to have a lot of confidence in the timing part of the equation.

I don't drive the truck a ton...so a few days might only be 50-100 miles...maybe even less depending on what I'm doing.

[mikeames]

I'm going to take the truck over to a local place in Vancouver (WA) called Wong's Performance Tuning. I'm told they are very well versed in GM tuning. I hope I can afford what they have to offer.
I like to do things myself, but I only have so much time to figure it all out.

[steveo]

I strongly suspect my timing match is botched, but I don't know how to fix it.

well you did kinda patch it up by dropping 8 degrees at the distributor. perhaps in that case dropping 8 degrees across the map, putting it back to normal at the distributor, then slowly bringing it back up would be a good starting point...

but without a knock sensor, kinda hard to do any decent knock logging; so perhaps you should consider installing one?

[steveo]

I have not tried unplugging the O2 sensor...although it is running closed loop.

well 'bout the only thing that'll change over the course of a few days that resetting the ecm would fix is closed loop blms.... so that's why i asked..

[mikeames]

well you did kinda patch it up by dropping 8 degrees at the distributor. perhaps in that case dropping 8 degrees across the map, putting it back to normal at the distributor, then slowly bringing it back up would be a good starting point...

but without a knock sensor, kinda hard to do any decent knock logging; so perhaps you should consider installing one?

I have considered that, but wouldn't I need to reburn the chip. I don't know how to do that.

[mikeames]

well 'bout the only thing that'll change over the course of a few days that resetting the ecm would fix is closed loop blms.... so that's why i asked..

So by that you mean that most likely my chip is burnt incorrectly for what I have?

[mikeames]

I'm confident I can buy a burner and figure out how to burn the EPROMS, but I have no idea what to change or how much. Way too many options.
I need to find someone local that can school me I guess.

[jim_in_dorris]

I'm going to take the truck over to a local place in Vancouver (WA) called Wong's Performance Tuning. I'm told they are very well versed in GM tuning. I hope I can afford what they have to offer.
I like to do things myself, but I only have so much time to figure it all out.

PM Dave W on this forum, he hangs out in that area Vancouver WA. and is super helpful in getting tunes straightened out. I am sure you will be pleased with his efforts. He can be found at http://www.gearhead-efi.com/Fuel-Injection/showthread.php?417-Old-School-EFi

[Fast355]

well you did kinda patch it up by dropping 8 degrees at the distributor. perhaps in that case dropping 8 degrees across the map, putting it back to normal at the distributor, then slowly bringing it back up would be a good starting point...

but without a knock sensor, kinda hard to do any decent knock logging; so perhaps you should consider installing one?

If he is running the 7747 without a knock sensor and has not turned off the forced knock test there is a good chance its the test itself not the spark map causing the knock.

[billygraves]

.....................

[steveo]

definitely good info, especially about the plug wires and shielding the pickup wires. i've gone through the exact same shit another car before, and now you reminded me to check mine out.

but yeah it does sound like it needs a retune

AFTER you resolve all other possible issues.

[EagleMark]

If he is running the 7747 without a knock sensor and has not turned off the forced knock test there is a good chance its the test itself not the spark map causing the knock.If he is running with no knock sensor and it is not turned off properly in 1227747 then the knock count just keep counting and pulling knock retard timing.

The forced Knock test is run during PE, WOT... just when you need forced knock right? D'oh!

If you have some high pixel size pictures of under hood EFI install I can usually spot any issues like high voltage RFI noise interfering!

It's time for you to get a ALDL cable and TunerPro RT to do some data logging! We'll find the issue.

AFI used to have great customer service... when I worked there!

[billygraves]

............

[EagleMark]

I'm going to take the truck over to a local place in Vancouver (WA) called Wong's Performance Tuning. I'm told they are very well versed in GM tuning. I hope I can afford what they have to offer.
I like to do things myself, but I only have so much time to figure it all out.


PM Dave W on this forum, he hangs out in that area Vancouver WA. and is super helpful in getting tunes straightened out. I am sure you will be pleased with his efforts. He can be found at http://www.gearhead-efi.com/Fuel-Injection/showthread.php?417-Old-School-EFiEven if Dave W from Old School does not have time I'm sure he will help you get TunerPro RT setup and working on your Laptop! Then we have something to look at and see what's going wrong.

It sounds like your fuel maps are pretty good if it runs well after a ECM reset. Sometimes these old engines don't like to run at Stoich which is what the O2 sensor and BLM learn is what they do. The way to tune an engine that needs to run Open Loop is with a Wide Band and take the O2 sensor out!

This still leaves your timing issue! As you've been recommended get a GM ICM, it is an important part and aftermarket ICM have been proven to be in-accurate with timing. There could still be other installation/conversion issues. If you were closer to Coeur d'Alene Idaho I fix these conversions all the time.

You say the injectors flow at 180? 180 what? These TBI injectors are usually pound per hr. If you look on the top there are some numbers, write them down and let us know what they are and we can tell what size. Running at 26 PSI is very high pressure...

Wish you the best! Good Luck! :rockon: