Fast idle, stumble on acceleration
 

I recently bought a 1987 560 SL with no idea of its service history. It insists on idling at 900-1,000 RPM, and stumbles on acceleration. Also, when I pump the brake pedal, the idle surges upward slightly. I've searched the archives, but don't feel like just randomly replacing parts. It sounds like a combination of things (idle control unit, plugs wires, etc.) Any thoughts?

Max J. Sandler

High idle
 

Max;
The idle increase when pumping the brake is typical,no repair needed.
For the other problems check thr o.v.p.,it's located in the right side footwell behind the side panel.
M.F.

Thanks for the quick reply. I've heard the OVP bandied about on this site, but am not quite sure of its function. How does its operation affect idle and/or stumbling?

The OVP fuse and relay can cause all sorts of idling problems. Check the fuse on it first. Please note that if your car was jump started with another car - it could cause the fuse on the relay to blow from voltage surge. Since you just got the car - CHECK THE OVP FUSE AND RELAY - first. It could be your problem. If the car sat for a while before you got it and they jump started it - could be it. Please advise if it cures your problem