Poor cold idle and high RPM misfire

Poor cold idle and high RPM misfire

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robsco

Original Poster:

7,836 posts

177 months

Sunday 27th May 2018
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Hi all.

The 2S is struggling at cold idle, I can't figure out whether the idle speed has just been set too low (idles around 4-500rpm and unless the throttle is held lightly for a minute or so, eventually cuts out) or whether it is anything more untoward. It had a 12k service a month ago. I also have a high RPM misfire under load; the car will accelerate hard but around 5000rpm or just above, it's almost like it hits a limiter and starts running rough. I haven't tried to rev through this as it doesn't seem the right thing to do. Could these two faults be related?

The car is a 2004 4.0S, 24000 miles. Ignition related or perhaps throttle bodies?

Thanks.