300e idle
 

I replaced a leaking EHA on my 1991 300e the other day,cleaned/washed engine .Started engine (eng temp cold)and all was normal so I went for a ride...ran as specified. turned off engine ,re started 1/2 hr later,idle speed 1500 in park!drove car several miles , idle returned to normal!Its acting like a stuck choke when engine is started warm after sitting for a few minutes!RUNS normally when started cold! ANY IDEAS?Unpluging the idle control valve with the engine @1500 reduces idle to normal.Any help would be greatly appreciated! THANKS,DAN

Try tapping on the OVP relay (behind cover behind battery, red fuse on top) when it's idling too high. If the idle returns to normal, replace the OVP relay, its' bad.

However, it's more likely the idle control valve is bad. Clean before replacing -- remove valve from car, fill with carb cleaner and cover the two holes, shake a bit, dump, and refill until the stuff comes out clean and re-install.

Otherwise, you have a computer problem that will have to be proberly diagnosed. You will need to check the EHA current and the duty cycle, verify that the O2 sensor is working problery, and that the mixture is correct. See the DIY article in the DIY forum, it helps.

Peter

Drove car to work today and all is well....could getting water someplace it shouldn't have caused this?I washed the intake side of the engine after changing the EHA to rid the area of fuel residue. thanks,Dan

Yes. Water in the electricals can cause all sorts of temporary problems form shorted or grounded connections.

Peter

Peter,thankyou for your reply.Do you know if it is possible to use dielectric grease in the electrical connectors to help prevent this?I've had this problem the last 2 times I've washed the engine .I've owned this car for 7 years now and not had prob lems with washing the engine up to this point.Any ideas??Thanks,Dan

yes, you can use dielectric grease, but I would recommend being very careful if you insist on washing the engine, and DON't do it at the car wash with high pressure spray. You're gonna corrode the connections someday, even with grease.

Peter