Another 124 Idle Issue. Help!!!!!
 

Our 124 Wagon (1994, E320, no traction control) has an ongoing idle issue.

The original harness was replaced, new plugs wires and coils. New fuel injectors. Tried 3 different MAFs. Same issue, which is…

…Idles fine when cold. When it’s fully warmed (80c), the idle stumbles. Drops from 650 ish, to about 400, if I recall correctly. Then it’s fine again for 4-5 seconds, then repeats.

That’s the whole story. Oh, a bit more - no check engine light, no codes, two mechanics have tried and failed.

Thanks,

Joey

The throttle body has the same bad wiring as the engine harness. Check to see if you have a original throttle body by looking for a date code on the green/white sticker on it.