Fast idle on start up

[anziani]

Hi,
I've searched the forum but could not find anything that addresses my problem. My '87 300E when cold, starts and idles at 1500 rpm. After a block it settles right down to 6-700 rpm and stays there for the rest of the day.
This started right after I had the indie check and lube my throttle linkage in the hopes that it would solve the surging problem with my cruise control (It didn't)
I have had it back to him but he cannot seem to find the problem. Any ideas?
Anziani
'87 300E 175K
'95 E 420 100K

[Mike Freeman]

Make sure the accelerator cable is not too tight and holding the throttle open.
Some mechanics unfamiliar with M.B.Z. will attempt to adjust the idle with the throttle stop screw which is only intended to keep the throttle from binding. (might take a look!)
Surging cruise control is usually caused by a bad amp and most original amps are bad.
Good luck and please post your fix Mike

[anziani]

Mike,
Thanks for the hint. I will pass it on. My mechanic only works on Mercedes and is very compepetent. That is why I am puzzled that he hasn't been able to correct the problem. My hope originally was that it might have been a binding linkage that was causing the cruise control problem. (Hope springs eternal.) I will bite the bullet and replace or rebuild the amplifier.
Anziani

[lkchris]

Idle control valve is a controlled air leak to provide more throttle to a cold engine.

Cruise control surging may be caused by bad speedo cable--does it surge in conjunction with shaky speedo needle?

[fz500sel]

When I first got my '93 400E I had the same problem. The problem turned out to be a bad ETA (electronic throttle actuator). Hope yours isnt the problem. It can be an expensive repair.