560 SLC rough idle

Our 560 SLC has a rough idle that we are unable to correct. So far we have:
Replaced plugs
Replaced ignition wires
Checked distributor cap
Ajusted air flow
Substituted idle relay
Checked for vac leaks in all injector areas

Seems to be on the #3 cylinder. Symptom changes with running - when warm it runs better than cold. Uneven running, or miss, goes away when reving to beyond idle speed. We have had this problem with other models also, for example in 420 engine.

Help

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Bob1

[Benzmac]

I have seen where the fuel distributor will do this at idle. Also a stretched timing chain will act crazy. I'd bet on the injectors or fuel distributor.

How about the spark plugs?

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Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

[Steve Guilford]

In your message you indicate having a 560 SLC. Where did you get a 560 SLC, or is that a typo ?

Steve Guilford
107 026 12 000677
107 024 12 011890

The car type was a typo - it is a SEC.

To BenzMac - Thanks for bringing up the timing chain. Now that you mention it we did one time do a timing chain on a 420 and noted that it idled better following completion of the job.

I think this will be the next thing we will try.

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Bob1