[thebenzmane55]

Ok, I am a Mercedes Benz Mechanic and my 420sel is only my winter car, But the problem i have is it idles rough and I can not figure out what is going on. I have put on distributor cap, rotor, wires, plugs, different ignition control unit, coil, almost everything for the ignition system, I have also run 93 octane with bottle upon bottle of injector cleaner, tapped on the injectors and everything. But still the car idles rough at idle. Do i have to tare the motor down and have the valves reseated? Has anyone else had this problem and was able to fix it with out engine work?

 

[Digital K]

I have a similar issue, the roughness dissapears above 1800rpms....

 

[Louie_D]

My 420 gives a kick every 30 seconds or so at idle and the oil pressure gauge bounces at the same time. Changed an extensive list of parts but still hasnt gone away.

 

[AxelWulff]

In addition to worn ignition components, you'd want to check the follwing:

- Vacuum leaks (very commmon issue...)
- EHA (electro-hydraulic actuator)
- Cold start valve
- OVP (over-voltage protection)