revvhappy

I recently bought my CLS6 with 181k miles and immediately had the timing belt/water pump/ plugs/etc done because there was no history available. The valves were adjusted and all passages in the intake cleaned also.

The engine idles at 750rpm and seems to miss occasionally that speed, but the thing that bothers me most is rough acceleration, more so when cold than when hot, but it's always there. The engine revs to redline but just doesn't seem as smooth as a v6 should.

I've been reading everything I can on coil-pack issues. Does a misfire always result in a CEL code? Mine does not throw any codes and no idiot lights come on.

Any other ideas?

Tosh

No, a bad ignition coil does not necessarily throw a code right away. If it's a bad coil you might be able to detect which one it is by pulling the connector while idling: if idle changes, then that coil was good. If idle stays 'lumpy' then that coil was bad.
But if the idle just misses occasionally that sounds more like a dirty injector or carboned-up combustion chamber. I would run a fuel system cleaner for more than 3 tanks, and then reassess.

revvhappy

Thanks, Tosh. Fuel system cleaner and checking the coils at idle are easy first steps in diagnosis.