Cousin's Grand Prix - lots of codes - stalling, problems starting

[dandragonrage]

Sorry in advance for the long length....


My cousin's got a 97 Grand Prix with the 3.8 (not SC) that sometimes stalls, and sometimes doesn't start. They sometimes coincide (i.e. not being able to start back up after it stalls) but not always - sometimes it won't start when it's cold, and sometimes it starts right back up when it stalls. It also "bucks" sometimes, and sometimes runs rough/crappy. The exhaust sounds choppy when it runs like crap but I'm not sure I'd say it's running rough enough to be running on 5 cylinders, nor do we have any misfire codes. But sometimes it runs just fine.

The starter seems very strong; it's not a low battery problem for sure. The car doesn't even try to get going when it's in this mood. Just the starter turning. Just gotta wait it out. I've done some very basic diagnostics and found some horrifying things but haven't fixed it. My cousin's low on money so he can't afford me just replacing sensors and stuff so hopefully you can point us in the right direction.

First, I checked the spark plugs (free to do, might as well, right?) and found Champions. What? No. Just no. Replaced them with Autolites which I gapped to spec for the car, .065 or something (if that number's off, it's probably just my memory - the spec was on the sticker under the hood). The store didn't have any AC Delcos in stock, but Autolite should be OK. Well, of course, I find that the jackass that put the Champions in also semi-stripped all of the spark plug holes because they won't go more than socket-by-hand tight. They do stay in but that worries us, and obviously the heads will have to be pulled to be helicoiled or replaced, but I think the plugs are in tight enough that that's not the problem. (Let me know if you think otherwise though.)

I cleaned the MAF/TB and the car was throwing an IAT code (amongst others, list below) so we replaced that since it was cheap. I just cleared the codes tonight so we're not sure if that code will go away or not. He's not willing to drive it because of the problem. I tried unplugging the MAF while it was running and it did nothing except make the car stall like a minute after I did it, but that might not have even been the MAF's fault as the car stalls anyway.

We found that there's a whine that sounds like a fuel pump from somewhere in the engine; I wonder if it might be a vacuum leak. It's not actually the fuel pump because it's most definitely in the engine bay.

Here are the codes I scanned with EFI Live:
-P0102 - MAF sensor low voltage - from when I unplugged it. I only list it to note that the computer does recognize the MAF, anyway.
-P0113 - IAT sensor high voltage
-P0140 - Rear O2 sensor no activity detected - don't care
-P0141 - Rear O2 sensor heater malfunction - don't care
-P0441 - evap - incorrect purge flow
-P1111 - IAT sensor high voltage
-P1641 - MIL circuit malfunction - I strongly believe the guy who sold him the car cut this circuit to hide the MIL that the other faults caused.


The obvious answer would be to lemon law it but unfortunately it's past the deadline for that. He's stuck with it.

Please help!



Thanks,

Dan

[GRRRR8]

These cars are known for 3 issues. Melted plastic intakes (coolant loss), cat.converter (hard start, stall, drivability issues) and fuelpump/connector issues.

3800s are great motors. They are very quirky when they have any type of sensor issues. I see it has both codes for the IAT.

A bad IAT can cause many issues. I would look at the plug and the sensor before I went too far.

[J Wikoff]

You might check out www.pontiacbonnevilleclub.com (shameless plug? ... maybe)

My two thoughts are screwy PCM or bad ground(s).

[dandragonrage]

We tried the new IAT and we drove it and it stalled and refused to start after less than a mile - fortunately it was in a loop and stalled riiiight off of the driveway so we didn't have to push it far. It wouldn't start for a while, and we finally got it and it started but only ran for like 30 seconds then stalled.

Gonna drill a hole upstream of the cat tomorrow (temporary, obviously) and see if that helps, I guess.

[WickedMom]

#99-06-04-005B: Driveability Symptoms Due to Clogged Fuel Injectors

Condition?

Some owners may comment on driveability symptoms of long or hard starts, chuggle, rough idle and light or intermittent misfire. The malfunction indicator lamp (MIL) may also illuminate.
Cause?

Due to various factors, the fuel injectors may become restricted. At this point, no specific fuel, fuel constituent, or engine condition has been identified as causing the restriction. The restriction causes the engine to operate at a lean air fuel ratio. This may either trigger the MIL to illuminate or the engine to develop various driveability symptoms.

[dandragonrage]

That would throw front O2 sensor codes for running lean, no? It's a possibility that I thought of, too, but I don't imagine it being the case. Not that I think it's impossible or anything, though.

[WickedMom]

I dunno, just trying to help... throwin ideas out there for ya...

[GRRRR8]

I would clear the codes as some are false and retest and see what you get.

[dandragonrage]

I cleared them last night and he's driving the car today so I'll report back when I get a chance to scan them again later.

[johnh]

Try looking over at www.clubgp.com as well.

[Purf]

Sorry in advance for the long length....


My cousin's got a 97 Grand Prix with the 3.8 (not SC) that sometimes stalls, and sometimes doesn't start. They sometimes coincide (i.e. not being able to start back up after it stalls) but not always - sometimes it won't start when it's cold, and sometimes it starts right back up when it stalls. It also "bucks" sometimes, and sometimes runs rough/crappy. The exhaust sounds choppy when it runs like crap but I'm not sure I'd say it's running rough enough to be running on 5 cylinders, nor do we have any misfire codes. But sometimes it runs just fine.

The starter seems very strong; it's not a low battery problem for sure. The car doesn't even try to get going when it's in this mood. Just the starter turning. Just gotta wait it out. I've done some very basic diagnostics and found some horrifying things but haven't fixed it. My cousin's low on money so he can't afford me just replacing sensors and stuff so hopefully you can point us in the right direction.

First, I checked the spark plugs (free to do, might as well, right?) and found Champions. What? No. Just no. Replaced them with Autolites which I gapped to spec for the car, .065 or something (if that number's off, it's probably just my memory - the spec was on the sticker under the hood). The store didn't have any AC Delcos in stock, but Autolite should be OK. Well, of course, I find that the jackass that put the Champions in also semi-stripped all of the spark plug holes because they won't go more than socket-by-hand tight. They do stay in but that worries us, and obviously the heads will have to be pulled to be helicoiled or replaced, but I think the plugs are in tight enough that that's not the problem. (Let me know if you think otherwise though.)

I cleaned the MAF/TB and the car was throwing an IAT code (amongst others, list below) so we replaced that since it was cheap. I just cleared the codes tonight so we're not sure if that code will go away or not. He's not willing to drive it because of the problem. I tried unplugging the MAF while it was running and it did nothing except make the car stall like a minute after I did it, but that might not have even been the MAF's fault as the car stalls anyway.

We found that there's a whine that sounds like a fuel pump from somewhere in the engine; I wonder if it might be a vacuum leak. It's not actually the fuel pump because it's most definitely in the engine bay.

Here are the codes I scanned with EFI Live:
-P0102 - MAF sensor low voltage - from when I unplugged it. I only list it to note that the computer does recognize the MAF, anyway.
-P0113 - IAT sensor high voltage
-P0140 - Rear O2 sensor no activity detected - don't care
-P0141 - Rear O2 sensor heater malfunction - don't care
-P0441 - evap - incorrect purge flow
-P1111 - IAT sensor high voltage
-P1641 - MIL circuit malfunction - I strongly believe the guy who sold him the car cut this circuit to hide the MIL that the other faults caused.


The obvious answer would be to lemon law it but unfortunately it's past the deadline for that. He's stuck with it.

Please help!



Thanks,

Dan



I had the same issue when I owned my 1999 Grand Prix GTP (supercharged). I think the issue, which took about three months to diagnose, including multiple phone calls from my dealer to Detroit GM, was due to the sensor that regulates oxygen and air. Once that was replaced, no issues. Prior to replacement, the engine would sometimes die with no warning going 65 MPH on the parkway. By the way, the 3800 in my Grand Prix was a great engine. Sold the car with 100K miles to buy my G8 and it still ran like a top. Good luck.

[dandragonrage]

What sensor (or part in general, other than the throttle itself) regulates air? I only know of sensors that measure air. Or is it a sensor for the forced induction (i.e. to regulate boost) that you're talking about? Or perhaps you mean the IAC? I suppose that does regulate air, but I don't think it would cause stalling at speed (or would it?)

[dandragonrage]

he took it to the shop before I was able to do anything that you guys suggested, and it turns out it was the crank position sensor. This was something I suspected because Google had shown me people having that issue. I had told him I would just try replacing it. Autozone had it for like $32. But he decided to take it to a shop and he paid like $180 instead. (Not actually that bad though.)

[supercharger]

Just saw this post and thought I could save the day....but you already fixed it. I have a 98 Regal GS and had to replace the crank sensor too but did not have all the crazy codes you did. I had a crank sensor code!. HOWEVER...I also had a sticking idle air control valve that would cause the car to stall and it would also start, then die. Eventually it would start and be OK for a while. I strongly recommend you replace the idle control valve too. It is not expensive and is super easy to replace. Just for shits and giggles take your valve out and try to move the plunger by hand. My guess is that you'll find it is FUBAR and very hard to move to the plunger, which should move easily on a good valve. You may even find that there is a lot of carbon buildup in the port the valve travels in. The Idle valve and its effect on fuel mixture could set all of those codes you saw as well as the stalling and hard start issues like it did on mine. IMHO, the crank position sensor will NOT cause all those fuel mixture codes you had. Something else was causing those codes that the new crank sensor will not fix. Idle valve, followed by the EGR valve would be my next targets if the problems reappear.

[dandragonrage]

I'll keep that in mind. Thanks.

[Seattle09GT]

he took it to the shop before I was able to do anything that you guys suggested, and it turns out it was the crank position sensor. This was something I suspected because Google had shown me people having that issue. I had told him I would just try replacing it. Autozone had it for like $32. But he decided to take it to a shop and he paid like $180 instead. (Not actually that bad though.)

I came to the party late on this thread and this is EXACTLY what I was going to suggest. As you just learned, it is a dirt cheap part, and rather easy to install.

As Charlie said - when sensors go out the GM 3.8L V6 becomes a very unhappy engine.