Misfire in cylinders three and four

Tiny
GREGORY GRABITZ
  • MEMBER
  • 1998 JEEP
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 120,000 MILES
Odd misfire in cylinder three or four. With both spark plug wires on I get a misfire. If I pull number three wire no difference missing. If I pull four no difference it is missing. If I pull both wires I get a double miss. If I put either wire on one at a time that cylinder three or four that I put the wire on will fire, put both back on and it misfires. It will do the same if I pull number three injector wire or number four. Whatever one I put back on without putting the other one back on it will fire.
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Sunday, October 9th, 2016 AT 3:38 PM

3 Replies

Tiny
HMAC300
  • EXPERT
With misfires I always have you go to a mechanic because it can be so many things wrong not like they used to be. check compression and for a vacuum leak also check for low fuel pressure auto parts rent guage. otherwise leave it to mechanic because it can be sensors or other things causing it. here is an article on how to do it.
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator
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Monday, October 10th, 2016 AT 6:55 AM
Tiny
GREGORY GRABITZ
  • MEMBER
Fuel pressure is good compression is good . In fact the jeep runs strong taking off and going down the road . Spark is strong, new cap, wires, coil and injectors. When it's idling I don't smell raw gas out of the exhaust. It's my daughter friends jeep she only makes minimum wage and as much as mechanics charge I could replace all the sensors for less. I'm thinking it has a short somewhere but as long as it's going down the road I guess it's good. She is going to get a new car this tax season so maybe I'll leave well enough alone. Thanks for your reply.
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Tuesday, October 11th, 2016 AT 7:03 PM
Tiny
KEN
  • ADMIN
Hey Greg,

It sounds like you have a blown head gasket between to cylinders that is allowing the compression fire ignite the fuel in the opposing cylinder at the wrong time. This is difficult to diagnose because the head must be removed to inspect the gasket. IS the compression a little low but exactly the same in each cylinder?
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Friday, October 14th, 2016 AT 11:26 PM

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