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-   -   lift-throttle vibration? (https://www.gmforum.com/1987-1991-93/lift-throttle-vibration-188297/)

theJMFC Apr 21, 2003 10:24 PM

lift-throttle vibration?
 
Does anyone here know what would cause a vibration when I get off the gas? It only does it at highway speeds (65-100 mph). It is similar to my usual tire-out-of-balance vibration, but more exagerated. The car seems to be more smooth under acceleration or even at a constant speed.

I'm sure there's a perfectly logical and expensive explanation for this phenomenon. Who knows it? Impress me, people! 8)

Jim W Apr 21, 2003 10:49 PM

Jon, the only time mine does that is when my cam magnet has not properly aligned my number 1 cylinder due to my ongoing code 41 issues (cam magnet). The performance is drastically affected and I get vibrations when I ease off the gas, usually, I know when the cylinder is out of alignment when I rev in park...are you getting an SES light?

I can only speak from experience...good luck tho :wink:

theJMFC Apr 23, 2003 12:13 AM

well guys, I'm getting no SES light. There seems to be no problem with the engine itself, and the vibration is more in tune with the wheel speed than the engine speed. I probably should have said that in the first place, my bad.

I hadn't thought about the CV joint, but that would make sense. It could be held in it's normal non-vibratory position when power is on, and then slack off and become out of balance when I release the gas. Hmmm... very interesting. I shall investigate this possibility. I assume that there is some inspection procedure in my haynes manual, in which case I will inspect them - on Friday.

Could be a wheel bearing, but there are none of the usual bearing noises to back up that theory. I know in my other cars with failed bearings, I could hear it before I could feel it. And, it didn't take as much speed to cause it.

Thanks for the ideas anyway. I just had to get a few second opinions, ya know? 8)


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