When my car is cold (70-75* F) it idles at 700-750 RPM. When the engine is warm (85*C) it idles fast like at 1500RPM. Is there an adjustment for warm idle speed that will not affect cold idle?
A pic of what to adjust would be great.
Thanks

 

My 1979 450sl starts up in any temp. and begins the idle at 2000 rpm and after awhile (5 to 7 mins) idles down to 500 rpm. I don't see anything wrong with the idle. I have taken my car on a few road trips and had no problem with the idle. If you are really concerned about the idle you will need to adjust the idle wire but, you'll need to get a timing meter.

 

Hello RdRunner! I'm a new member with the same problem. Did you ever find out what to do to correct this problem? Thanks!

 

they should go up to around 1000 rpm and shortly drop down to 500 and stay there. I'd start with vacuum leaks first. then pop the idle control unit out of its plastic case and let it run, then wiggle each component on both sides and see if there's a change in idle. or look at them with a magnifying glass. there may be a bad soder joint. could be the slide valve/idle control valve too. check for bad connections by wiggling the connections while running and look at them for burn spots.

 

Thx Brookings!

 

the suggestions I gave were for the 107 sl. vacuum leaks would apply to any sl.

 

Thanks again to all for the assistance in solving this problem!

It turned out to be the rotor/cap after all as suggested by members on the forum!
The problem was where the rotor rides in the cap had worn, and I would have never saw it if it hadn't been for a good friend of mine who was a MB tech at one time and spotted it immediately.
So, changing out the rotor/cap is a cheap fix and now will just become part of a maintenance schedule for my car.