560sel won't idle well
 

need some help, my 560sel,1990 model just won't hold idle. my rpms most of the time are around 4-5thousand. if the air is on or if you come to a stop at a light or sign then you are going to stall. replaced the plugg and wires what else could be going on?

Check OVP in the fusebox. Happened to my 380 and that cured it.

not the ovp relay just the ovp inside the fuse box which one is that?

Before touching any electronics check for vacuum leaks otherwise youll be there longer than necessary.

After cheking for the vacuum leaks and doing a pressure test, then check the ovp and mas, fuses and relays, sensors, harness and make sure the electrical devies are working. Also build your a self tester to check the mas for error codes.
Having a very similar problem with my 190E2.6 and I have replaced the OVP and MAS and car still doesnt run. So the point is buying this or that part will not necessarly solve your problem.

how to build a self tester? already re did the fuel injector o-rings and cups replaced all of the hoses and vaccum connectors except the 2 inder the manifold those 2 are a monster for someone with big hands.

http://pages.prodigy.net/jforgione/MB_X11.html

I suggest bookmarking that site has some good info.

I have some documents that show what pins out of the 16 pin connector(in battery compartment) to connec to. To test the ecu connect the2 test leads from the test to pins 2 and 3.
To test mas for error codes connect it to 4 and 16(I think) might be wrong, woudl have to look at the document agian.
you probally have the cfi fuel injection system and would first the wiring harness for continuity then actually test the components of the fuel injection system.

johnlo, Did you get your problem solved?

not yet been out of town on business this weekend did get home until 8:30 sun night. will look into it tonight if possible.