My car vibrates pretty noticeably and annoyingly whenever it is stopped in reverse or idle. For instance it is most noticeable when stopped at a stoplight, and I usually shift to neutral to make it stop. It idles perfectly in neutral.

Any suggestions? I've thought timing belt, transmission...but I'm not sure where to start first and can't seem to find any decent information on this.

 

May sound a little goofy, but check the three motor and tranny rubber mounts. They are notorious for going bad.

 

The front motor mount was actually just replaced, and upon inspection I was told the two side motor mounts were fine.
Not sure about the tranny mount...is it hard to check at home?

 

There are only three mount points, one in the front of the car, one on the front of the engine, and the other above the tranny on the drivers side, so it sounds like you are fine.

If you have a manual tranny, you would also have a thrust strut that might need replacing. If your clutch is worn down, it can also cause some strange issues - usually slipping, but can cause vibrations if it is unevenly worn down.

It is possible that you have a torque converter going bad. Torque converters are basically centerfuges that spin and the faster the spin, the more fluid is forced thru the trannys valve body which then allows the shifting to higher gears to occur.

If it becomes unbalanced, it will vibrate. If the fluid passageways becomes blocked, it may also vibrate as it will become unbalanced. If the valve body becomes worn enough to not properly push the fluid around, it will become unbalanced and vibrate.

 

I've got an ATX, so I'm thinking the torque converter is a good possibility.

Also, it tends to shift hard on acceleration at times, depending on how fast I'm accelerating and how warm it is outside, etc. I'm thinking this is probably it, but I've also read Throttle Position Sensor and Throttle Body, so I might look into cleaning the body and replacing the sensor before I pull out several hundred to go to the tranny...

 

Have you check to see if any vacuum line (s) came loose - have hole or broken? i don't think it is a motor mount if so you would get a bump noise when foot is on the brake while putting car into gear. there should be a
(VECH) label located under the hood it will give you a drawing of how the vacuum lines are routed check them very carefully you should fine your problem there. time for a cold one and some pop corn

 

Let me know what you fine

 

Alright I'll have to do that. I suspect if I have a vacuum leak, that could also cause the slight stumble I get when I floor the accelerator from idle.

 

i have a 98 4 door dohc auto tranny ive had the same problem for a few months now and cant figure out what it is that rough idle cause my brakes not to work fully either ive replaced plugs with e3 got better wires and have a screaming demon coil pack, also had all the vacuum lines redone and new brake booster still rough idle unless in neutral. its bad enough now that sometimes at a stoplight or sign the car will stall. had it at the shop they say it has either burnt vlaves or piston rings but i dont lose any oil