corolla sr5 sometimes shakes when idling

[Jonnin]

there will be times when im driving and i come to a red light and all of a sudden my car just starts to shake and rattles a bit but when i put my car into neutral all the rattling and shaking starts what could be the cause of this possibly a motor mount that needs to be replaced?

[Rhyno811]

when its shaking does the RPM decrease and when you put it in neutral does the RPM go up?

[BeatupRolla]

sounds like ur idle is too low... try raising it, its free and easy.. it helped with my crappy idle..

[Jonnin]

when im idling the rpm is at 500 and when i put it in neutral when the car starts to shake it increases to about 800 and comes down to about 700, at the idling being alot is a good idea its adjusted abit maybe its not enough

[tashirosgt]

This is a long shot and I can't explain why this happened. I had the same symptom on my '90 (with AT) and they were fixed when I replaced the connector to the alternator. I replaced the connector after the alternator stopped charging and I noticed one wire to the 3 wire plug-in connector to the altenator had broken. (I had to replace the whole connector since the wire broke off right at the back of the connector.) My theory is that before it broke, the connection was intermittent.

[tashirosgt]

I should add that when my car had the shakes, the engine would surge gently every few seconds when idling. It stopped surging when in neutral.

If your engine is running normally and you get the kind of shaking where your steering wheel (and everything around it) vibrates up and down a little when in gear and stopped, a common problem would be bad motor mounts. My car still has a that kind of vibration It does go away when I put it in neutral.

I'm told you can test for bad motor mounts by using a pry bar around the mounts to hold up the engine while it idles to see if that stops the shaking, but if the car only vibrates when in gear, that would be dangerous.