[W126 Coupe] rough idle

[__]

Howdy Tim, I once corrected a cold-rough idle problem by using an offset
Woodruff key on the right side camshaft.  It compensated for a bit of chain
stretch.

 

-----Original Message-----
From: mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes-bounces at mbcoupes.com]
On Behalf Of Tim Graney
Sent: Thursday, August 09, 2007 11:53 AM
To: 'mbcoupes'
Subject: [W126 Coupe] rough idle

 

Here is a question for all you guru's out there. I have a 1985 500SEC Euro
AMG which I have pretty much replaced every top part on the engine and it
still idles rough when it is cold . I replace all the elements that control
the idle. The box, the valve, the fuel controller, warm up regulator. It
starts right up and idles to around 850 RPM nice and smooth then starts to
stumble a little bit like it is running fat. It runs fine once you take off
but stumbles a bit unitl it reaches operating temp. As soon as it reaches
80C it smooths out and runs and idles perfectly at 500RPM. I replaced all
the sensors on the motor. The only two I have not replaced are the two
thermo time switches. I also did the heads and replaced all the hydraulic
compensators and lash caps along with all new valves and springs. I just
cleaned the the surface of the heads about .002 to give a nice mating
surface. All the wires have been replaced. New Cap, New Rotor. I have
adjusted the fuel mixture ad nauseum. I use a vacuum gauge and a exhaust gas
analyzer and like I said it run tits when warm but crap when cold. Any
Ideas?

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