1995 LeSabre Vibrates/Spudders at 35, 65 MPH

[seanohio]

Greetings,

I have a 1995 LeSabre with 88K miles. One morning, I drove the car to work and noticed it spuddered going up the on-ramp to the freeway (typically 35 MPH) as I accelerated.

Then it would drive normally until 55-65 MPH, at which point it would vibrate/shake very badly. When I took my foot of the accelerator, it would stop vibrating, even if above 65 MPH, and drove smoothly and normally.

This has been going on for a few weeks. A local mechanic gave me a free estimate that said engine performance was the issue, though they didn't know where to start (they suggested a spark plug and ignition wire change).

We have speed-bumps in our community, and I'm wondering if I went too fast over one and that's caused the problem . . . not sure of what else. Any thoughts?


Thanks!

[ChemMan]

Codes?

[seanohio]

I don't have any as the check engine light isn't on. The mechanic didn't provide any either.

[ChemMan]

I would call and ask, as this sounds like a misfire or transmission problem, which should set a code. It will be much easier if you have a trouble code to start with.

[HotZ28]

A local mechanic gave me a free estimate that said engine performance was the issue, though they didn't know where to start (they suggested a spark plug and ignition wire change).

I think you need to let your mechanic proceed with changing the wires & plugs to begin with, especially if it has been awhile since this was done. If that doesn’t resolve the issue, you may want to consider the coils next.

BTW, this particular OBD1.5 PCM will not display misfire codes for a scanner to read. That started with OBD II PCM’s in 1996.

[ChemMan]

Originally Posted by HotZ28

BTW, this particular OBD1.5 PCM will not display misfire codes for a scanner to read. That started with OBD II PCM’s in 1996.

Are you sure? I have a 1995 Lesabre that had a pcm that was not firing the #4 injector. A scanner retrieved both the random misfire code and the misfire in #4 cylinder code.

[HotZ28]

Are you sure? I have a 1995 Lesabre that had a pcm that was not firing the #4 injector. A scanner retrieved both the random misfire code and the misfire in #4 cylinder code.

Thanks ChemMan for bringing this up. Actually, it has been a long time since I have scanned a model specific, 95-LeSabre. This is some good information to have. As we all know, 94 & 95 was the transitional years to OBD II. Many things changed during those two years!

I was just wondering how you had a single cylinder P0304 (# 4) misfire, and also a P0300 “Random Misfire” without having other problems? It is strange that one injector would cause “Random Misfire”. (More than one, or all)

I have a 94 LeSabre OBD 1.5 & an 96 OBD 11 PA Ultra, sitting in the driveway. I use a Matco Tools 9640B pro scanner, with the latest software updates, on both cars.

Unfortunally, my 94 OBD 1.5, will not read misfire DTC's. Maybe it is in the ability of the scanner, but I doubt that! The 96 reads P0300-06 DTC's using the same scanner. It could be that this feature was added in some 95’s. It would be nice to here from others with 95’s, to see if the majority were equipped this way.

[ChemMan]

Originally Posted by HotZ28

I was just wondering how you had a single cylinder P0304 (# 4) misfire, and also a P0300 “Random Misfire” without having other problems? It is strange that one injector would cause “Random Misfire”. (More than one, or all)

I remember getting the random misfire initially, and later on it became #4 misfire. It was a strange problem because it was intermittent, and would come and go for days at a time. Initially I replaced the injector and it seemed to clear up, but reverted a short time later. It took quite a while for my father and I to troubleshoot it. I finally started to understand what was going on when I read a book my father has on computerized engine controls. I became intimately familiar with the engine controls on that car. I should mention that the auto xray scanner my father has could pull up quite a bit of information on the car while it was running, seems more OBD 2 than OBD 1.