Incorrect Idle Speed Due to Stuck Idle Air Compensator on Mercedes-Benz 420SEL

It is not uncommon for the idle air compensator to get stuck in one position, resulting in the engine idle speed (rpm) being too high or too low. Replacement of the failed compensator may be necessary to correct this concern.

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Average mileage: 147,641 (58,000–210,000)
2 model years affected: 1990, 1991
7 people reported this problem
4 people shared problem details
when engine is running and shift to drive gear and pressthe acceleration the engine shut off
idles about 2000 rpm on hot engin in park and 900 rpm in dr
Hard starting when Engine Is cold. High idle 2000 rpm-900 rpm in drive
Sometimes idles to high. More often than not. Hard to crank after sitting awhile.
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