I am considering buying a 1991 500 SL which suffers from a rough idle condition.
Once teh engine is warmed up everything seems ok, excpet maybe that I imagined I would get more power. The roughness to me sounds like a stuck valve, but nothing shows up on a compression check.
Any ideas??

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Regards
Vince Alfonso (in Hong Kong)

92 MB 600 SEL
94 MB 600 SL
92 MB 500 SL (for sale)
93 BMW 740i

have it pluged into dealer or better yet independent shop computer takes about ten minutes
will tell you everything but the color of your socks............
William Rogers........

I agree with the previous post. Check for diagnostic codes either by taking it to a mechanic or doing it yourself as explained many places on this website (recommended). You'll want to specifically check the CIS fuel injection (socket 3 of the diagnostic connector) as well as the ignition (socket 8).

Check all idle air circuit hoses - betcha some are heat fatigued and cracked.