I still cannot solve my idle problems on the 88 300SE which I may start calling by the name of my many MGBs of the past "British whore". I had this beloved name for all of my MGBs because all they did was take my money and screw me. Now, the Benz has never left me stranded and never makes me wonder what, if anything will happen when I turn the key, but I'm starting to get just as frustrated. I know the problem is my inability to properly diagnose the situation so it's my inability rather than the car but man I'm going mad!

Rather than goin through what I've done, let me jusst give one item and two questions. Once warmed, if I remove the fuse on the OVP, the idle definitely changes for the worse. If I insert the fuse back, the idle imnproves. Is this an indication the OVP is working properly?

Second, I removed and cleaned the idle control valve. Once warm, if I unplug the electric connection it does NOT change idle at all. I can plug it back in and still no change. DOes this mean the idle control vale is bad?

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Thanks,
Ron Brooks

Ron, your reference to an MGB is a major insult to your Mercedes and to my ''B''.
As a present owner of an 1974 ''B'' and as a previous owner of 3 other''B's'' and ''A'', I know the the ''prince of darkness'' can be a real pain.
Sorry I can't help with your MB problem.
MGB were never designed to idle properly. It would seen a smooth idle was outside the capabilities of MGB engineers.
But on a nice summer sunday afternoon, I still prefer my old ''B'' for a nice country road drive.
JackD

I changed my "air slide valve" which is a little air pump that smothes idle on the M117 motor. If it doesn't operate at idle it could be bad or the controller could be bad, or both. I think you can check it for voltage. Do you have the manual? Sorry that I don't know your motor better.

I changed the valve and controller. Had a ICU problem that was the final culprit. I assume you have been through the primary ignition.

Steve

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Steve
1985 Mercedes 500SL Euro (Gray market)
1995 BMW 520i Euro (Gray market)
1992 BMW 525it Wagon
1994 Honda Del Sol Si

I have a similar problem with my 1985 380 SE and I have concluded- after switching the idle control valve with my gf's 380 SE- despite extensive cleaning with brake cleaner and then lube with wd-40 as recommended-I need a new idle control valve.

The spikes in idle are very intermittent and hard to predict, but I have narrowed it down to that component. Sounds like that could be your problem also.

Electronic contact cleaner is recommended not, carb cleaner or brake cleaner. I do not know if there is any rubber components in that valve. That is what I used not, carb or brake cleaner. I never recommended that. Those things are too harsh. They will break down the rubber if, there is any in there sealing. That in turn will cause a internal leak. Also, forget the WD-40. I actually found out that does not work well. It actually made the problem worse if, you oversaturate or put too much in the idle control valve. The recommendation came from another posting specifying WD-40 but, it actually made the problem come back. I do not have a idle control valve but, a purge valve where the idle control valve should be. Don't ask me how it works but, it looks and is positioned where a idle control valve (other W124s)connects to the engine on one side and charcoal canister on the other side.

Forgot to add. Use a good electrical contact cleaner. One that is safe for plastics and circuits. They are usually the more expensive ones usually are the more expensive ones depending on weight.