i have a 95 gst automatic with about 129,000 on it, just bought the car a couple days ago and i noticed when im idle it shakes, its not really bad sometimes its more like a vibration other times theres a bit of a heavy shake and then as soon as you accelerate its fine i was thinking maybe egr valve or oxygen sensor maybe....anyone have any thoughts let me know

 

What are the rpm's at...are they low? Does it only do it when its cold? Do the rpm's drop low when your comming to a stop?

 

if the car is running and in park it doesnt do it and the rpms stay right at about 1, with the car in drive and idle it kinda fluctuates from 1 and a couple notches above 1 and its constant even after the car has warmed up, the other thing i noticed about the car is when i shift to reverse it jerks

 

Check your engine mounts if they are worn/borken it'll make the car shape at idle or shift hard. Also check the crank pulley for any seperation.

 

check the air bleed on the car, that happened to mine and no one recommended looking at that. some come loose or lose their threads. Its located by the throttle body; looks like a screw. If you remove it and put plumbers tape around it, it WILL fix the problem, cheap ghetto fix, but been running strong for 2 more years since the fix.
Or just get a new one, if thats the problem.
Hope this helps!

 

ok so ive checked the engine mounts and they appear to be fine, just replaced egr valve and im still having the same problem, someone suggested that it might be the cat converter

 

Are there any engine mods? Do you know if it still has the balance shafts?

 

the following things were done/installed when i bought it, a greddy bov, a alarm system that looks poorly installed, a boost gauge that is plugged up an a couple other gauges that are unplugged, a greddy turbo timer that doesnt really appear to work, i think thats everything, someone mentioned that if there were a bunch of stuff hooked up and it was a hack job of installing it and if they cut into any wires or anything that it may have tripped something and that could be whats making it rough idle, ive heard a number of different things it could be, number one was the egr valve, idle air control valve, bad plugs and wires, pcv valve, clogged cat converter, air flow sensor, timing, and on and on and on

the previous owner said there were new plugs installed a month ago but wasnt sure how long its been since new wires were put in, that they noticed it started idling rough when they replaced the belts(which by the way whines and squeals horribly in the morning but appears to look new, i was told it might not be tight enough but it appears to be pretty snug) the other problem ive noticed is the headlights and interior lights pulse and dim, if your idle they get really dim and when you accelerate you can watch it pulsing, i was told it could be the alternator but that also is new, not sure if it was reconditioned or brand new, and again i was told that all of it may be caused by the same problem perhaps, the car just seams to have a bunch of little issues but the price was a real steal i didnt think i could pass up

 

Did you check the crank pulley and see if its seperating? Its pretty common they do that and can cause damage to the timing belt if it gets bad enough.

Are you getting a check engine light?

Btw an o2 sensor will not cause a car to idle poorly or shake.

 

no i havent checked that out yet, someone had made the comment about the o2 sensor, ive had them go out in the past but never had that problem so i wasnt too convinced that would be an issue, there are no lights on at all except the brake light and it keeps going on and off till the car is warmed up then it goes off