missfire

[chip]

I have a 98R mini cooper 1.3i with a serious misfire.I have tried more or less everything.I have put new H T leads on and new plugs, new fuel
filter, set tapets,engine compression test and had it at fuel injection center. It's been 2 rover and no fault found on ECU. Also had it on a rolling road and has had a crank sensor.The person who had it before had same problem and had it in at rover on numerous occasions but nothing was found.The problem seems to happen more when engine is warm. It is ok when
you just touch the accelerator but if you put your foot down it feels like it is holding back.
If you get it up to 4000/5000 rpm you can feel it struggling as well.Anybody any ideas?

 

[Xracer]

Sounds like a fuel pump, fuel filter, or injector....you're not getting enough fuel at higher RPM.

Things like this are almost impossible to diagnose at a distance (and not at all easy close up either, apparently)....

Does it feel like a general misfire or that maybe one cylinder missing?

 

[ThomP]

I agreee with Xracer; sounds suspiciously like fuel starvation. The fact that it does this more when warm would make me think a sensor is failing after it reaches engine temperature rather than being an injector.

 

[Graham]

Any possibility of a weak valve spring ?