Fast idle on my Mercedes 500SEC
 

Hi, Can some one help me?
The car idles fine when first started, but as some as i move the car and brake the idle then runs fast.
Can anyone tell me how to fix this?
It is an auto box.
Thank you
Andy
P.S. Does anyone one know how i can get a book manual on this car?
Thanks again!

All things related to SEC high idle are detailed in the mbcoupes.com archive. I would start by looking for vacuum leaks related to the idle control valve--expect there is a feedback circuit to purposely increase the idle when the tranny is in-gear, and maybe that tubing is open somewhere and over-compensating when that feedback is activated.

My printed manuals came from a friend, though occaisonally they will show up on E-bay; rare and expensive, though worth it in comparison to the scanned images on the CD. Cheers, Andrew Seidel.

500SEC high idle
 

I have simlar problem with my 1985. it seems to go into a high idle about 1200 RPM after driving it awhile. Just starting to drive it again with Spring weather and it is a bit of an anoyance. I have not figured it out yet either. There are no adjustments and a leaking vacuum hose seems the best bet.

I have the Factory manual fro MB and it does not seem to be much help.

To start with what year car is the 500SEC?? Also is the car a US or rest of the world version?

Overvoltage relay OR fuse is a likely problem if the idle goes up to 1800!