Car ran fine just a day before I swapped in a 97 Camaro pcm in space of my 96 pcm, car fires up, and won't even idle right.
misfire counter shows it's misfiring on pretty much all cylinders, pcm came out of a automatic, while my car is a manual...
can't get much data because the thing runs so poor that I can only log a few seconds before I have to shut it down...
if someone has any ideas thanks in advance.
ps Plugs|Wires|Coils are all new
The ICM often takes a dump at the most in opportune times;
Have you swapped the Ignition Control Module? If not, a local junkyard should have one for fairly cheap, My vehicle had refused to start / run at all due to a failed ICM.
Also, there is a ground wire that runs from the harness to the ICM, and this is often forgotten to be placed back onto the block. This is the ground for:
02 Heaters, Instrument panel, ICM/PCM and a number of sensors within the harness. Make sure this ground wire is attached.
What was the service code and calibration four letter code on the ecu sticker. There were four possible car models with the same service code ecu but a different stock map depending on the car model. I am looking to swap in a 97 Camaro/trans am ecu into my 96 3.8. I don't know what ecu calibration code to look for though.
16227797 is a 97 ecu but could be for a camaro/trans am, grand prix/bonneville supercharged, monte carlo and park ave/regal/riviera. There is a 4 later code after the service number
If the ecu was from an auto it could be a MAF problem. Apparently the manual and auto cars had different MAF sensors. One is a two screw fitting and the the other a three screw fitting this might mean that the throttle bodies are different. I'm not sure but might be worth checking out.
the one I ordered from ebay I made sure it came from a 97 Camaro, but I never noticed the last 4 letters until you mentioned it... on the sticker mine says 16227797 CACBOriginally Posted by Dan86
I think you might be right, according to some data I logged, I am having a misfire mostly on 2,5, changed the coil packs around, and I'm still having a misfire on 2 mostly and those coil pack sits right were the water gets to them when it rains, stupid design by GM for sure... my fuel trims are also off, and I can't seem to get the maf tuned, and I think this might be the reason why..
I think they're all the same for all 4th gen, those things are mass produce across a ton of GM vehicle, I've looked a few tunes that days manual, and did a compare, all the maf tables seems to be the same.
If the ecu is not from a camaro/firebird and is from a park avenue/regal or whatever I'm guessing that the injector flow rate would be off if they use different injectors. This could explain the fuel trim issue and the multiple misfire codes.
Don't make the mistake I did, make sure it's for a Camaro or Firebird, otherwise, you won't be able to write the PCM, HP Tuners doesn't support it even if the service numbers match up, I think it as to do with the VIN#.
I think I'll have to put my old PCM back in, and see if it's in fact a tune file issue
Last edited by LuminousX; 11-13-2021 at 01:28 AM.
swap the ECM or flash the ECM from the park avenue with the file from the Fbody.
Still failure?
Swap the ICM with a junk yard ICM, Replace with new ICM if found faulty. Use AcDelco's ICM. More $$ but longer life.
Still failure? Check to make sure your Fuel pressure is 45LBs on idle, 49-55 On WOT.
My issue, was the ICM, Backfiring, bucking, stalling and over all poor performance, was solved with a new ICM and a Fuel line repair (Fuel filter connection was leaking, allowing air into the fuel system)
I've yet to fully test everything, but I once unplugged the MAF sensor, and the misfire went away, I read somewhere that while the MAF is connected the ICM controls the ignition, if disconnected then the PCM takes over,
never followed up on it though, but I think that was a clue that my ICM was bad...
From what I have investigated regarding the ICM, I have not found a 100% positive test to prove the ICM is bad, other than to swap out the unit for a known working one.
Ive Experienced the ICM work fine under idle / low RPM conditions, and completely crap out under 50%+ throttle under load.
If you navigate over to "camarozone.com" there are entire threads of people chasing issues related to this, and it turned out to be the ICM. They are rather common to blow up on the 3.8's, especially ours cause they are heatsoaked all the time.
I was unaware unplugging the MAF would introduce the ECM to control the ignition, as the spark timing is controlled by the ICM completely as the ICM is its own "computer" of sorts, the ECM just tells it when to fire.
Unplugging the MAF would likely throw the car into "limp mode" where the timing is either put far into advance, or retarded.
I'd Suspect the ICM first as you already have replaced the coils, wires, n plugs. the only thing left in spark distribution is the distributor, which in this case is the ICM. Swap it with a junk yard ICM for now, if it changes the behavior? You found your culprit. If it makes it Slightly better? you need to keep on looking.
The ECM's in the GM's are rather robust, I have read they can handle up to 24V of direct power and still be okay, as they are tested to withstand this in "torture" tests GM rolled out on them.
the ICM's? Not so much.
Got a new ICM, no change... Tested the unplug MAF, no change in the misfire, but the idle did smooth out ever so slightly..
a top having all this issues my OEM oil pressure sensor decided it was time to go, and left a bunch of oil on the ground,
not sure if I should be grateful that all it did was left a mess, and not while I was driving on the highway..
at this point I think I'll have to pull the #2 injector, I think it might be sticking... I've primed my fuel pump, and watched the pressure fall quickly before,
and then theirs time when it hold constant pressure.
Update on my misfire problem, took out the #2 injector, and it's pretty much spraying like a water gun, no misting at all... funny thing is, when I was cleaning them during my turbo build, I notice it was spraying different from the rest on that bank, and I opt to put it on the front for easy access, I guess it slipped my mind, but this thing isn't working like it's suppose to, and no amount of cleaner is fixing it..
How did you do that test? Looks like that injector is unhappy.
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