Chaps

I have recently aquired a 1994 C280 I6 M104.

It has a problem:

Car starts fine, idles fine when cold.

When engine starts to warm it goes lumpy, rough and if driven surges.
It will rev freely and once above about 1000rpm is sweet but when accelerator pedal is released the revs drop and sometimes stall and sometimes runs lumpy again.

Once the engine is warm it is beautiful, smooth, idles and revs freely.

Its only rough when warming up.

OVP is new type, bypass relay does work but I am curious to find out when it should kick in.

What are the sequence of events when the engine is cold to when it is warm, what switches in and out?

What other things could I try, Coils etc. can be ruled out as once warm it purs like a pussy cat.

Si.

I just got my 94 c280 ~350 miles ago, this sounds like vacuum problem, but I'm not positive. These gas burner MBs are new to me!! Good Luck, I'm hoping someone that knows more than I will help out.

__________________
If it ain't broke take it apart and find out why.

1983 300SD, 4 speed
1994 C280
1987 300TD wagon
1996 HD Road King

Ride in Peace Eric Peterson, Harley of Macon