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rough idle 4.0

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Old 12-09-2011, 12:28 PM
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Default rough idle 4.0

99xj has missfire on 3&4 cylinders. Just replaced plugs wires cap and rotor and did not help. Sprayed intake and vacume hoses with carb cleaner and did not change idel. What else should I check?
Old 12-09-2011, 12:43 PM
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Compression
Old 12-09-2011, 02:29 PM
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x2 could be a blown head gasket between 3 and 4.
Old 12-09-2011, 07:25 PM
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My buddy had the same problem with his and his head gasket was bad. Had a mis in #1 & #3 cylinder.
Old 12-09-2011, 09:07 PM
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Compression is 30 psi on 3&4. I think it is a head gasket or the head.
Old 12-09-2011, 10:51 PM
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I would say just gasket, considering you have a distributor (I would think cuz you said you changed the cap and rotor), which means you probably have the 0630 head which is pretty solid. In late 99 they started to use the 0331 head which is prone to cracking, but I believe those all had the coil packs instead of the distributor. Not that it's impossible for the 0630 to crack, just alot less likely.
Old 12-10-2011, 01:13 AM
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compression check then change the head gasket.
Old 12-11-2011, 09:07 AM
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Thanks, I am going to replace the head gasket now.
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