1981 380 Sl Idle Problem / HELP
 

1981 380 Sl idles just all of a sudden like the car had a radical cam in it. Very ruff idle until 1200 or 1500 rpm. As the car warms up the car runs somewhat better, but the rough idle is still there. When driving & keeping the car at higher rpms everything is ok. However, let off the gas & rough idle returns & engine may even stall. If this happens it will only restart after it has sat for a few minutes, like it was flooded? Have replaced frequency valve, oxygen sensor, excess voltage protection unit and the spark plugs. Upon replacing the plugs I found all the plugs on the right side to be very black with carbon. While the plugs on the left side were not a perfect light brown, they were close and much better. Also, the fuel economy gage on the dash indicates the cars economy is way off from what it was. Any ideas on what suddenly went bad with this car would be appreciated!! Help :confused:

Do you still have the original single row timing chain installed? The 81-82 380SL's have a high failure rate. If it jumped a tooth or two on one of the two cams, it will do what your experiencing. There is a conversion to double row timing chain available from MB.

If that is what is happening, please don't run your engine until worn chain and components relating are replaced. If you let it go, it will experience catistrophic failure! BB

Cam is ok. Engine runs fine at higher rpm. Thanks for taking a shot!

Sounds like you have a vacuum leak that you need to track down. Check for broken or disconnected fittings in the engine compartment. Also be sure your door locks hold vacuum.