heavy miss under load
09-29-2009, 01:02 AM
#1
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Year: 1988
Model: Cherokee
Engine: 4.0L
heavy miss under load
so i just rebuilt my engine bored it 30 over and put a very light cam in it. engine ran great on start up break in and for two very short test drives. engine is now missing under a load most of the time. sometimes it will miss with out load just raising rpms. also has noise sounds like coming from exhaust when it happens. anyone have a suggestion?
09-29-2009, 07:48 PM
#5
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Year: 89
Model: Cherokee
Engine: 4.0
Did you do the rebuild?is it possible the lifters are adjusted to tight,when you first start them up it takes a little time for hyd lifters to pump up and once they do they can cause the valves to hang open slightly cause this condition.
09-29-2009, 08:08 PM
#6
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Year: 2004
Model: Grand Cherokee
Engine: 4.7L V8
Did you mill the block and/or head mating surfaces? If so, and it was both, there could be an issue with the pushrods being too long now. JMO
Last edited by ol"blue; 09-29-2009 at 08:10 PM.
10-15-2009, 11:02 PM
#7
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Year: 1988
Model: Cherokee
Engine: 4.0L
thanks everybody for your sugestons.head was surfased but not block.valves are not ajustable. i have replaced map/mat censer. sugeston was made that the computer does not reconize the rv cam.also the knock censer could also cause the mis. help.ido not want to put in a stock cam.thanks. engine starts great-runs good untill it warms up.then the motor idles good but starts to miss as i rev it up .please help .
Last edited by harleybiker2; 10-19-2009 at 08:41 AM.
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10-16-2009, 12:22 AM
#8
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Year: 1990XJ/1989MJ
Model: Comanche
Engine: 4.0L Renix
You said a heavy miss under the hood. Do you have one of these..............
under your hood???
under your hood???
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