Help!! RPM in Park at 900 RPM

[1badzr1]

Noticed recently when comming to a light or stopping the Idle is a bit high. Is there a rely that controls the idle? If so I would like to replace it to bring the idle back to normal at 500 RPM. This high idel is causing a slight vipration through the complete car. When driving at speed all is fine. This is causing the trans to make a humming sound as well. Can I replace the idel relay to correct this problem if so where is it? Has anyone experienced this in their cars if so what was your fix. As stated the car runs fine when moving and in Park. Only in Drive at a stop does the Idle rise to 900 and noise begin. Thanks BR

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[HBcarnut]

Originally Posted by 1badzr1

Noticed recently when comming to a light or stopping the Idle is a bit high. Is there a rely that controls the idle? If so I would like to replace it to bring the idle back to normal at 500 RPM. This high idel is causing a slight vipration through the complete car. When driving at speed all is fine. This is causing the trans to make a humming sound as well.

Can I replace the idel relay to correct this problem if so where is it?

Has anyone experienced this in their cars if so what was your fix. As stated the car runs fine when moving and in Park. Only in Drive at a stop does the Idle rise to 900 and noise begin.

Thanks
BR

Now my answer isn't benz specific, but this is a real common problem w/ a faulty EGR valve.