Can someone tell me why my car shakes??

[Denise]

Here's my problem...... the car runs fine while in motion, BUT... when I'm sitting still the whole car vibrates like crazy, it calms down a little if I put it in neutral. Any ideas?!?!
Thanks ~Denise~

[Devilboy28]

It has a rough idle?

[Devilsy2k]

I have a 3.4 too,and mine does the same thing, and i know its not a missfire because i replaced all 3 coilpacks, spark plugs, wires, all filters and it still shakes(has a rough idle). I have to sheke my leg at the stoplight so i dont feel the car vibrating [img]smile.gif[/img] . But when i'm cruising or at WOT everything seems fine and it goes to red line with no problem. Maybe its just the way 3.4s idle or maybe it has a vacum leak that I dont know about.

[Denise]

No, I don't think rough idle is the problem. We've adjusted the idle and it doesn't take care of it.Thanx anyway though. [img]smile.gif[/img]

[Bass482]

Check your motor/tranny mounts.

They could be worn/broken.

[Denise]

Nevermind my last post.... Ya know, I don't know as much about cars as I'ld like too. Sooooo, if something that I say sounds "stupid", please don't give me a hard time.O.K.? Not that anyone hasyet, just be nice to me please [img]graemlins/crybaby.gif[/img] [img]graemlins/dunce.gif[/img]

[Devilsy2k]

Denise, when your car is sitting still and you give it a little gas to raise rpm, does vibration goes away? Bass482, im not sure but wouldnt car still shake while driving if it would be a broke engine/tras mount?

[VHodgesOU]

I agree with Bass482...the reason it doesnt shake while driving is because the engine will smooth itself out...if that makes sense...also in neutral it wont shake as much because there is hardly any strain on the mounts from the engine...my brother's car did the same thing as you describe and we checked his motor mount and sure enough it was split right in half

[Denise]

Denise, when your car is sitting still and you give it a little gas to raise rpm, does vibration goes away?

Really it doesn't do it just sittin there in park... the only time it vibrates is sitting still with it in gear.

[good2Bking]

So it doesn't shake when the car is in Park or Neutral, only when you have the car in Drive with your foot on the brake and the engine is at idle. What if you give it gas (not enough to break the rear wheels loose) and keep your foot on the brake? Does it do it then?

I've never had an automatic transmission or done any sort of work on them, so I'm posing this question to automatic people. Could it be a problem with the torque converter? Since she doesn't have the problem when the engine is disengaged from the tranny.

[Denise]

Thanx guys for all your ideas.... gives me a few places to start. ;)

[Bass482]

<blockquote>quote:</font><hr> ...the reason it doesnt shake while driving is because the engine will smooth itself out...if that makes sense...also in neutral it wont shake as much because there is hardly any strain on the mounts from the engine...my brother's car did the same thing as you describe and we checked his motor mount and sure enough it was split right in half <hr></blockquote>

This is exactly what I was thinking. My younger brother has a 2000 Sunfire, he replaced his motor-mounts with polyeurethane (SP?) bushings. Now, his car shakes like a mofo when his foot is on the brake.

I think the reason for the car smoothing itself out would be that the engine is putting less strain on the body of the car because it is not vibrating on the body itself, it is transferred to the drivetrain. When your foot is on the brake, the engine can't transfer its vibrations to the drivetrain, because it's not moving, so it vibrates on the mounts. Likeweise it wouldn't vibrate the car when you're in park/neutral because there is no stress on the engine, so it will idle smoothly.

With my bro's car, the car vibrates because the mounts absorb all the vibration in the car. It actually vibrates throughout the RPM range, but it is a little worse with the foot on the brake.

Does that make sense? [img]graemlins/dunce.gif[/img] Just a thought.

[Big Tymer]

My car had it badly! After I flushed my engine... it only does it a small bit....

[Denise]

Thanx again !!!! All you guys are soooo sweet! I love this site ;) [img]graemlins/love.gif[/img]

[Marky82]

My '87 Trans-am had something similar to that and it turned out to be the transmision mounts.