4.0L with three dead cylinders
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Have a 1996 XJ 4.0 with a persistent misfire. I have done piston rings and head gasket but still cylinders 1-3 are completely dead despite good spark and known good fuel injectors. Did compression tests on 1-3 and their readings were all below 60psi, 4-6 were acceptable. 1-3 perform exceptionally well on cylinder leakdown tests surprisingly. Unplugging fuel injectors for 1-3 does not change the way the engine runs (even all at once) but unplugging 4, 5, or 6 makes the engine die. This has had me stumped for an embarrassing amount of time, any advice appreciated.
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Year: 96
Model: Cherokee (XJ)
Engine: 4.0
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using logic,
if you have spark, fuel and air verified, and the relevant cylinders dont leak, but have inadequate compression;
that would suggest valve train actuation is somehow improper, have you checked relevant clearances of pushrods, cam etc ?
I would certainly hook up a mechanical vacuum gauge, a very cheap tool but will give you some clues
Do you have any OBD2 codes ?
if you have spark, fuel and air verified, and the relevant cylinders dont leak, but have inadequate compression;
that would suggest valve train actuation is somehow improper, have you checked relevant clearances of pushrods, cam etc ?
I would certainly hook up a mechanical vacuum gauge, a very cheap tool but will give you some clues
Do you have any OBD2 codes ?
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