Problem with 1995 Cutlass Supreme 3.1L

[jpom]

Hopefully I'm posting all this in the right place, and hopefully somebody can give me a hand. I'm not overly knowlegeable about this stuff, but I'm pretty much at the end of my rope regarding this problem.

 

Back in August I started to have a problem with my car bucking. Essentially Whenever I accelerated I could feel the car buck and my RPM Gauge would just go wild -- up and down, up and down, also the low oil level light would come on, but the car would not stall.

 

I shut it off and had it towed to the garage that night, the next morning they worked on it and had the same problem, by the end of the day the problem had stopped. They kept the car for another 3 or 4 days and could not recreate the problem, they could find nothing wrong, got no error codes returned or anything. So I took the car back, drove it and 2 days later it started again, I got the car home and parked it for the night.

 

Next morning it started but I barely made it to the garage, the garage is a 5 minute drive from my place, 10 if you hit all read lights. This time the car would start bucking and then stall every few feet. I would turn it off, start it again and then coast another few feet. The mechanics looked at it and had problems with it for the remainder of the day and most of the next, after that the problem just went away again. The mechanic said that he thought maybe it was just a loose connection to the computer that had been tightened when he took everything apart and put it back together.

 

So I took the car back and have been driving it for probably a month or so now with no problem. Yesterday I was making a hard left, and I felt this one large lurch (i thought i had been rear ended at first, that's what it felt like) and the car started bucking again as I was accelerating, it did it for about 5 minutes and then quit, I drove it to the garage and jsut as I entered the parking lot it gave another big lurch and started again.

 

The problem doesn't seem the be affected by hot, cold, running time, or anything else that I can see. It seems to be completely random. Something I have notcied as of late as well is that when I accelerate the car hesitates. If I press on the gas it'll take a couple seconds for anything to happen.

 

That's the history of the problem, the mechanic is now saying that he suspects the Powertrain Control Module. I would like to hear any thoughts or suggestion anyone here has. The problem is that the mechanic hasn't said that it is the PCM, just that he doesn't have any other ideas. While I'm all for the process of elimination, considering that I have dumped close to $1000 into this single problem so far and it has not been fixed, another $3-500 to find out the problem still is not fixed would not be fun.

 

So Suggestions, thoughts, comments would be much appreciated.

 

TIA

James

[GP1138]

I had that exact same problem, and it ended up being the crank sensor wiring - I had routed it around an exhaust manifold part and the wiring's insulation melted, shorting the wiring and corrupting the crank sensor's signal, and the problem was exactly as you describe, the tach would jump all over the place and the car would buck and jump.

 

I'd check that, but I'd also look into a PCM problem too.

[badassoldspower]

Yeah check up on that crank sensor, it could just be getting shorted out.

[jpom]

Well I mentioned to the Mechanic about the Crank Sensor Wire, he said the checked it already. The only option I really have left is to replace the PCM and hope that fixes it.

 

Thanks for the suggestion.

 

James