W124 260E - curious misfire when warming up

[Lucky 7]

Hello chaps!

My F reg 260E's occasionally experiencing a choppy idle & stuttering at low revs ten minutes or so after starting out from cold (fine higher up the rev range). I've had a search through the forum and it appears there's a few things to try - however this one's slightly different, as it goes away again after about 5 minutes once the engine is fully warm and there's no further problems

It seems like there's only an issue during a specific temperature range (just before it's up to full operating temp), as I stopped off somewhere yesterday shortly after it had returned to normal running and the misfire was back when I returned, the engine having cooled a little. Will be checking the plugs, dizzy cap etc first of course, however I'm wondering whether this indicates that the coolant temp sensor is playing up? Hope not as it looks like an ar5e to get to!

Any help would be much appreciated, by both me and my wallet!

Cheers...

 

[grober]

Have a close look at the plugs to see if any particular cylinder/s are different from the others. Sounds as if you have a slight misfire which may be disguised when cold by the fast idle/mixture enrichment. Have you checked for a blown cylinder head gasket? Usually on cylinders towards the bulkhead end of the engine.

 

[Lucky 7]

Had the HG looked at a few weeks ago in fact due to some coolant loss, the mechanic reckons it's fine - I hope he's right!

Yeah I intend to change the plugs anyway this weekend and possibly the dizzy cap, although £34 stings a bit .

It's just strange that the misfire disappears again after 5 minutes or so, once it's fully warmed up, and the car is then trouble free for the rest of the day! It only seems to happen from stone cold too