Noticed a miss at 3500, pushed the engine (drove heavy in 1st & 2nd 4000rpm range) nothing abnormal happened, miss became more apparent. Replaced wire & plugs, Air & fuel filter, with no change, swapped in new coil pack, no change. The engine misses/bucks (it is as if a gremlin is switching of the ignition) at just over 4000 when cool (block temp not water temp) as the block temp rises or load duration (climbing a grade) the miss/bucking will drop to around 3000rpm. If the truck is rev'd to 3000rpm in park (Revs on held constant but it is being pushed to raise block temp) and with in a minute or two the engine will miss below the rev limiter which is about 3300rpm. However, this does not effect the trucks driveability under 3000rpm (if a break stand is preformed the engine will turn the tires over), the engine runs strong, at no point is there any smoke, or other signs of issue. And to top it all off, it will not throw a check engine light and the computer does not have any codes when read with OBDII scanner from Parts Store. I am curious if the 'cat' can cause this? By the way no noises from the Syncro either.
I am beating my brains out trying to figure this one out. Would greatly apprecaite any assistance or ideas.
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Wednesday, September 12th, 2007 AT 3:08 PM
