PeachParts Mercedes-Benz Forum - M117 High Idle Diagnostics Thread

Hey everyone,

I know some of you have been through this before...

A friend of mine has a MY90 560SEL, it has a few problems, one of which is a high idle.

He just had it up at my indy's shop for a new chain/guides/ball joints

They also replaced engine rubber and tried to figure out what was causing the high idle..I also looked into this myself prior to the car going up to the shop and thought it was vacuum issue...

WHAT IT DOES
The engine will start out with an idle of around 700-800 when started cold.
Then as the engine warms up the idle will begin to sit around 1500.

If you shut it off, and let it sit for a few minutes, it'll restart at a lower idle..but after a few minutes it'll sit at 1500.

I swapped out IACV, Idle Control Computer with the ones from my 420SEL (no idle problems) and there was no change in the engine's idle.

I'm open to any ideas/comments/suggestions/hints/tips/thoughts you guys are willing to provide.

Thanks

Kris