skipping hesitating misfiring please help | Ford Explorer Forums - Serious Explorations

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skipping hesitating misfiring please help

DickyDanger

Active Member
Joined
September 6, 2014
Messages
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City, State
Dracut, Ma
Year, Model & Trim Level
2002 Mercury Mountaineer
i have a 2002 mercury mountainer 4.6 v8 awd with just over 130,000 miles. i have a flowmaster exhaust with a side pipe that exits right in front of the driver side rear tire. at certain rpms on light to medium throttle especially going up hill the truck skips and hesitates. i have changed all 8 spark plugs and all eight coils. while doing so i noticed two spark plug holes one on each side of the engine had oil in them and its not appearing to come from the valve covers. i don't have a check engine light normally all though on a weekend trip home pulling a trailer with atvs on it the check engine came on for random misfire.after clearing that code two weeks ago it has not come back on. is it possible the the oil is leaking from a bad intake plenum gasket? when the truck starts skipping and hesitating i can hear it through the exhuast as well as feel it as im driving. as far as i know the plenum has never been off. does this sound like my issue? the gasket kit is only like 40$ and labor is free to me. any help is great;y appreciated thanks for taking the time to read my post
 



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I would check cylinder compression first. Oil outside the engine after heavy loads , along with the misfires leads me to believe there is substantial blow by.

It "could" be from a clogged PCV valve also.
 






checked all cyclinders when i did the tune up and all the cylinders had good psi readings on my compression tester. its not a lot of oil but there is oil where it shouldent be, i just ordered a pcv valve since i over looked that on the tune up and it was under 3$. and i already have the intake gaskets and nothing to do after work so i might as well take it apart just to say its been done.
 






also want to add it just 130,000 miles which in my opinion i feel is very low for a 2002 and its mechanicly and physically in great shape otherwise. i will report back later tonoght and let you know how it goes i was asking about the plenum gaskets because i have read they can be a common problem on these bad boys
 






Try this. When it begins to stumble, back off the accelerator, then get back into it with the same pressure. I bet the tranny downshifts and the "mis-fire" stops.

My 06 is doing a similar thing, and I can "cure" it every time by doing that. On two occasions I did get the TPS A/B mis-match code and the wrench light w/limp mode. I suspect it is either the TPS or the torque converter.
 






that makes sense. i know i have a bad solenoid pack that i have not been able to afford to replace i wonder if that is making me think misfire/stumble/hesitation. i just scanned the truck and i have zero codes except for a left rear parking aid sensor circuit malfunction
 






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