1994, Shuts Off, Misfires, Bad ECM? [SOLVED]

[ingoditrust8208]

I have a 1994 Bonneville SSE Non-SC and it has a bit of an issue. After replacing the entire fuel system from which why the car was being sold I began to test drive the vehicle around my home in the country. I immediate noticed its "odd" running abilities and random complete shutdowns. It seems as if the vehicle was running with a hiccup, feel the jerk in the engine, and obviously if my foot was on the gas it would just chug along so to speak. Typically if I were to slow down or not have my pedal on the gas it would stall completely. Now it may sound like a possible fuel problem but I assure you it isnt. I have had a camshaft code that sputters on and off during the operation process, obviously replaced this sensor in means of fixing the problem...no luck. Next step I was told to check to make sure the camshaft magnet was still attached to the timing gear which it was but for safe measure and for the sake of making sure I replaced the entire timing gear set and put in a brand new magnet incase the old one in some way was faulty. Again the problem remains. I have switched out an ICM board to further test if the issue occurs. The car already has new spark plugs, spark plug wires so that likely eliminates those scenarios. I cant see any damage to the wiring from the sensor through the motor so if it is a short its beyond my sight. I am leaning towards a possible bad ECM but before I go ahead and cough up the money for it I would like some more opinions and options in the matter on other likely solutions. The car itself is in good shape and it is a shame the only issue I have with it is this random shutting off and unusual sputtering when in idle and drive.

Thanks

[myfirstbonnie]

When you say the entire fuel system, can you be more specific? What parts were actually replaced?

Disconnected the battery for 15 minutes to clear the PCM. Take it for a drive long enough for it to be at operating temp for awhile and then have the codes read. See what comes up and report them back here.

Clean the TB and IAC orifice with TB cleaner (not carb cleaner). Clean the MAF with MAF cleaner.

[ingoditrust8208]

When I mean fuel system I meant fuel pump, fuel relay, filter and even some fuel line, all these were faulty and rusted away (in areas) yet somehow the car would start here and there when I first bought it. Lines where cleaned out all the way up through the rail during this replacement process.

I will get the specific camshaft codes codes and reply back.

[myfirstbonnie]

Not just a camshaft code, any codes in the PCM.

http://www.pontiacbonnevilleclub.com/fo ... =51&t=8893

[Jrs3800]

Start the car in the driveway and let it idle.... will it or does it eventually stall out? Like you turned the key off?

As well when the Stalling happens, does the Tack drop to 0 but the speedo still report speed?

Also look for code P1361

[RPACODY]

Some of your symptoms (stall at low rpm, odd running, jerking) could point to
A bad fuel pressure regulator – did it get replaced or checked for a diaphragm leak?

[ingoditrust8208]

P0705- Trans Range Switch Circuit
P0342- Cam Signal Circuit
P1565- Cruise Servo Position Sensor Circuit

Obviously the cruise control one is not my main concern but the trans range is a new one since I last had it scanned with the same issues.

The car sometimes runs absolutely fine for well over 200 miles and other times I cant even get it out the driveway.

Let me know your thoughts guys, remember I have already completely gone through replacing camshaft sensors, checking the wiring all the way up through the engine with no ability to find any damage or possible shorts when running.

Thanks

[Jrs3800]

The trans range will not cause it to not start, or stall for that matter... But it can cause a no start if its bad enough...

The cam sensor or sensor circuit can fail and the car will still start, run and drive... The cam sensor is there merely for a #1 TDC reference for True SFI....

The cruise we will throw out the window at this point...

Did the scan cost you anything at all?

at the same time it would be nice to see a fuel pressure check... Key on you should see 41-47 PSI, Idling can be lowish say as low as 38-39, blip the throttle and you should see 45-47 easily, either that or pull the FPR vac line and see what the full pressure is...

Its possible to have a bad PCM.... The 94-95 PCM was funky at best and more than most of the time never failed 100%, most of the time it was very intermittent and left you chasing your tail... A lot of the time it would however be accompanied with a code 1361 .... Your case is a bit confusing, but I don't want to see you waste your money either.. I have 5 PCM's for the 94-95's sitting here, 2 of them failed with a code 1361( dead giveaway for me )... One failed in an odd way dropping the 4000 Pulse output for the cruise / Chime module( had the T2V variable steering function as well as the system monitor and oil level warning, so my car would ding ding ding off the hook now and then with a check gauges light ..... The other 2 simply would not run for crap, could not idle right or start right for that matter, and would be doggish on the road...

Also curious if you have ever pulled the PCM to see if its a Reman unit or the original ?

[ingoditrust8208]

Scan doesnt cost me anything, I know the owner of the local garage very well.

I have never touched the PCM in the car ever, as far as I know its the original but yet again I did buy the vehicle with over 190k miles. And yes I forgot to tell you I had the fuel pressure checked, sits around 40psi when at idle, didnt check it when tapping the gas.

Like the topic says, I am fairly certain its the PCM because of not only how odd the issue is when attempting to resolve the P0342 code, but the inconsistency of how the car operates everytime I put the key in.

I would 95% most likely gonna buy a brand new non-reman'd computer and have it put it if thats the definite issue here with the vehicle.

[Jrs3800]

That is worth a shot... after re reading your first post, it seems almost as your describing a bad PCM... Its still worth a shot, but no promises...

when my van( 95 Trans Sport ) was updated with a series III 3800, we went to the 97 PCM to avoid the issues with the 94-95 PCM's( the 3800 vans used the same PCM as the Bonnevilles )... Never could get it to run quite right... When the van was updated to the newer PCM the odd problems went away...

My 95 Bonneville was updated for the same reason... Got tired of those 94-95 PCM's...lol

[givemewings]

Not to chance the subject or changing the subject only slightly. Why does the EPROM have to be swapped from old PCM to new or used PCM? I've never had a car have PCM troubles until now so I am new to the whole computer issues.

The shop I took my 97 Bonneville to claims I too need a diff. PCM. My electric engine fans will not turn on with the defrost or A/C running, I don't know if they will even turn on when the car gets hot since I've never let it get real hot. But the shop's computer would turn the fans on, my PCM won't. I'm going to be buying a used PCM out of a 99 SC Bonneville shortly (hopefully it runs the fans).

[Jrs3800]

The 1997 and 1999 PCM's are not the same... Your 97 wiring pin outs are different... Unless you repin and reflash the PCM, the 99 PCM will not work for you... 97 only for a direct swap..

[givemewings]

The 1997 and 1999 PCM's are not the same... Your 97 wiring pin outs are different... Unless you repin and reflash the PCM, the 99 PCM will not work for you... 97 only for a direct swap..

Thanks for the response even though its slightly uncomforting to hear. I usually try to get all my parts used to one recycle good used parts and two save money. Finding a 97SSEi in the salvage yards around here might be a chore. Most are the 92-95 Bonnevilles

[ingoditrust8208]

I just want to update everyone that a new ECM (computer) did the trick.

Car no longer has ANY check engine lights, runs much nicer and I am happy that this issue is finally fixed after nearly a year of *fook* with it

[Jrs3800]

Glad to hear it...