RPM fluctuations when idle

[uk_jih]

Hello,

When my car is idling at traffic lights the rev counter fluctuates between 500 and 750 RPM.

It also feels as if the fly wheel is off balance because there is kind of vibration from the engine.

When in motion, sometimes you can still feel the vibrations.

Any ideas?

 

[Hal Fisher]

Sounds like something in your idle control system. Your idle is dropping too low, thats why its starts rattling. What year/model/engine?

Hal

 

[uk_jih]

Hello,

It is a 1992 3.0 engine.

I first noticed the problem when I was actually doing 50 mph and I could feel the vibration then. I did not see a fluctuation of the revs at speed but the vibration was very evident.

Regards
John

 

[LNM]

jih

Have you tried cleaning the crud out from inside the air intake?

Search for "poor idle"; there's rucks of stuff about it for W124s.