View Full Version : Random bucking and stalling

Duke George V
09-12-2010, 04:56 PM
Having a little trouble with the van I just bought. 1995 Trans Sport, 3.8. Prior to this, the check engine light would come on randomly when starting the van. Shutting it off and restarting would turn the light off. Recently though, the engine will cough while driving and turn the light on. Last night, when going to a job, it stalled while idling in my parking spot, then when I was waiting at a traffic light, it died and wouldn't restart for a while. This of course upset the people behind me, but what could I do? I got it started again and moved to a nearby parking lot, where it stalled twice more while just idling. I tried tapping on the MAF sensor and the coil packs to see if they're at fault, but I got no immediate response.

I'm a little baffled. I know it's not transmission-related, since it happens both in drive while moving and in neutral while stopped. I don't know how to read check engine codes from a '95. The "paperclip trick" probably doesn't work, huh? I don't really have any money to pay for a diagnostic at a shop. Any ideas?

09-12-2010, 05:04 PM
Check the wiring harness....the section between the engine and the radiator where it loops down by the starter. The harness at that section is exposed to the elements and is a source of corrosion. Pull back the plastic sheathing over the harness and take a look at the individual wires. If one is broken or swollen, cut out the bad section splice in a new section.

09-12-2010, 09:08 PM
Go to an Autozone or somewhere they will scan it for free. It could be a number if things.

09-12-2010, 09:26 PM
Have Auto Zone scan it - defore you do anyting else.

If I had to guess I would say ignition module, or crank sensor may be getting intermittent.


09-12-2010, 09:41 PM
I don't trust those scans....I had virtually the same issue in my '95 and the code came back on cam sensor and egr valve. It was several corroded wires in that section of the harness. Bad wires gave bad codes.

Duke George V
09-12-2010, 10:53 PM
Autozone won't scan it unless it's '96 or newer—basically it has to be OBD2. That's why I asked about the paperclip.

09-13-2010, 05:37 AM
The can scan it, as long as it has a OBD2 plug. If it has a OBD 1 plug, then its a OBD 1.5, which is still scannable, but you have to buy one for it.

09-14-2010, 03:28 AM
Try unplugging the maf and starting it, *most* cars will run with it unplugged, Iv diagnosed quite a few MAFs by just unplugging them and driving them

09-14-2010, 01:31 PM
The can scan it, as long as it has a OBD2 plug. If it has a OBD 1 plug, then its a OBD 1.5, which is still scannable, but you have to buy one for it.

Actually, some GM cars used the OBD2 plug even when they were still OBD1.5

The van is OBD1.5 with the ALDL, But you have to have a cable and tool capable of reading the GM 1.5..... Some will read the Odd ball 94-95 GM's other will not..

I think there is another issue with this van, but it does need to be scanned to at the very least point us in a good direction.... This could be anything from a bad PCM, to a bad wire... Crank sensor or the EGR.... But we need to know what the PCM is seeing and can hint at...

Duke George V
09-16-2010, 09:07 PM
Van died on the freeway today. Freeway Service Patrol was kind enough to confirm that there was no spark whatsoever from any of the coils while cranking. I made it to a junkyard and grabbed a module and a set of coils. Hopefully that will cure this, and it's not, like, the crank sensor.

09-17-2010, 12:43 AM
....no spark whatsoever from any of the coils while cranking....

Crank sensor, probably. Each of the 3 coils is a separate system. They share a crank sensor, power supply, and SOME of the logic circuitry in the DIS module. At cranking speed the ECM is not involved in producing a spark.


Duke George V
09-17-2010, 05:32 AM
No problems to report. I replaced the coils and ICM as a set from a dead '92 Bonneville, and drove it most of the day for work without incident. I'm glad it doesn't seem to be the crank sensor; I've heard it's something of an ordeal on this engine.

09-18-2010, 07:23 PM
Actually its not an ordeal... Remove the belt, yank the crank bolt.... Use the proper puller to remove the balancer... and the Crank sensor on 93-09 3800's are all set it and forget it as they do not need any adjustment.. Reassemble and be happy... Air tools do make it a lot easier tho...lol

Glad you got it fixed, the ICM is another common problem with high miles... Been through a couple myself..

Duke George V
10-01-2010, 08:04 PM
And I'm a liar. As I said before, the replacement parts I got were from a '92 Bonneville. Yesterday the van failed to start at all, so I figured that the parts I bought were already nearly dead. I just got back from the yard, having procured a set from a '99 Park Avenue, slapped 'em on... and nothing. Does this mean it really is the crank sensor?

10-02-2010, 11:39 AM
Do you have spark at all? The ICM actually controls the spark for the start, if you have no spark then the Crank sensor may be the culprit...

Duke George V
10-04-2010, 03:19 AM
Does fuel pressure regulator sound like a possibility? The van started today and ran just fine. I shut it off after a few minutes and it wouldn't restart. I can hear the pump running. I'll check for spark tomorrow.

10-04-2010, 12:51 PM
FPR will not cause this. It can cause a no-start, but only by flooding the engine. If the FPR fails, the engine will flood and fuel will come out the exhaust so bad you will smell it after one or two start attempts.

This sounds like an ignition or crank sensor issue.

10-09-2010, 02:15 AM
I just had this problem with my 89 Ciera Coupe w/3.3. The problem at first was a slight rough idle and then after a few weeks it died like I had turned key off and would not restart until it cooled off. Turns out I had one injector that was shorting out (no ohms) and was causing all injectors not to squirt fuel, hence no start. Finally discovered if I unplugged the one injector that was bad it would run on the other five injectors (though a little rough) but at least I finally got it home. I should add that there were times when heat played no part in restart since at times it would not start no matter how long the car sat. Hopes this helps.

Duke George V
10-09-2010, 05:55 AM
I doubt it's bad injectors, since this engine runs sequential fuel injection, not batch fire like the 3.3.

Duke George V
10-15-2010, 01:16 AM
Crank sensor replaced, all is well.

10-15-2010, 07:21 PM
How long did it take?

Duke George V
10-15-2010, 08:54 PM
A couple hours, I guess. I had to have a shop do it, since I am contractually prohibited from working on my car in my apartment complex.

10-16-2010, 06:13 PM
Oh good point, that's right. I remember when security rolled by while I was refilling the coolant in my Legacy. I thought I was gonna get busted but they just ignored me. Apparently coolant doesn't count. :D

10-16-2010, 08:19 PM
So it's running like a true emperor finally? :D

Duke George V
10-16-2010, 11:17 PM
Yeah. I had taken to calling it Princess George instead because of how pissy he was being.