W124 Idle Surge

[Bazzman]

Hi folks

My E200 W124 '94 M111 engine is doing real odd things.

Starts Ok from cold, but after reversing out the garage, usually when I'm closing the door, the revs increase from 1000 to about 1500, for a second. The car is in Park so no problem.
It has done this for a month or so now.
Up to now, that was it. But it's doing it more often now, when I'm driving, and usually when I'm just waiting to pull out from a side road, and my foot is just resting on the brake!
when warm or hot, it's 100% OK.
I've checked the database, and looked at the OVP relay, and it is an early type, dated 93. Could it be that? Or any ideas?

Thanks
Barry
Surrey England

94 W124 Wagon E200 103,000 miles

[Bazzman]

I just took a second look at the OVP on my car.

It's dated 93, but has the part number 201 540 32 45.
Any ideas what this is?
Is it a very old type?
I'm in England, but RHD cars would have the same OVP, wouldn't they?


W124 E200 Wagon 1994

[Mark Stetson]

I can't answer your question directly, but I'm experiencing a similar problem with idle surge on our '93 300TE wagon (W124 chassis, 3.2L six). Do a search here for OVP, also for idle speed, idle surge or surging idle. There seem to be two culprits - the OVP relay and the idle speed control switch (valve? module?)

[G-Benz]

I have had this problem for over a year now, and I also have heard that the transmission "Reverse" and "Drive" switch (or sensor) can send bad codes and cause this effect...I will one day research this and find the absolute source of the problem.

In the meantime, I had replaced the OVP some time ago to cure a hot start problem, but the surging still exists...so rule out the OVP