First post here! w124 idle issues

[bobkat]

Hello everyone! I just bought a 1988 300E (with 122k miles) two days ago to replace my 1982 300SD (which has accumulated 274k miles).

I am slowly sorting out all the problems with the w124, but i am still having idle issues. On the first day the idle was all over the place, very incosistent. I did new plugs, wires, distributor, and fixed a small vacuum leak and now it idles like a purring cat at about 700 rpm.

The Problem: With my foot on the brake I move from N or P into D or R and the idle drops to 500 rpm and the car becomes rough. If i'm in park or neutral with or without the brake the idle is smooth.

Is it normal for the idle to drop from 700 to 500 (i have never had a car do so), and what do you think my problem is?

I'm new to the w124 world, so i bare with me if this is a simple easy to fix problem, i used search and couldn't really figure anything out.

 

[Ian B Walker]

Not sure but sounds a little like advance and retard problems. Check the vac lines going to the ECU (ignition block on r/h inner wing). Also remove the air cleaner and look to see if you have any dirt around the circular flap valve. It should sit flush in its housing.

edit.....BTW welcome to the club, have fun