1999 Jeep Wrangler Engine missing

Tiny
RONP99
  • MEMBER
  • 1999 JEEP WRANGLER
  • 6 CYL
  • 4WD
  • MANUAL
  • 120,000 MILES
In the morning the jeep cranks and idels fine. Between 150-190 degrees it starts missing. It looses power and acts it will quit running. Once up to engine temp, about another 1/4 mile down the road, it runs great. It never misses from then on.

When you shut the engine down and leave it for around 10 min and restart it it will starts missing again.
This will last for about 2-3 min and then it runs great. It will repeat this every time you shut it off and restart.

I have changed the plugs, wires, muffler, tailpipe and air filter. I took it to the jeep dealer and he ran the 23 point check with no problems. They couldn't or wouldn't take the time to evaluate the problem.

I pulled the plugs this morning. No 5 cylinder plug is different than the others. It actually looks like it is not getting gas. But the engine runs fine and seems to have adaquate power.

I recently purchased the jeep so I have no history with it.

Thanks for the help.

Ron
Wednesday, June 2nd, 2010 AT 7:46 AM

3 Replies

Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
If the #5 plug is lighter compared to the rest of them, you may have a bad injector or a vacuum leak on that intake port. Try carefully spraying carb cleaner around the intake port for 5 if no reaction there may not be a leak, if idle quality changes, then you have found a vacuum leak.
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Wednesday, June 2nd, 2010 AT 8:07 AM
Tiny
RONP99
  • MEMBER
  • 2 POSTS
Sorry guys but you act like the Jeep dealer. If I hadn't said anything about the spark plug what would your response be? What about the catalytic converter? Could it be stopped up? Or the Oxygen analyser? What else could be the problem?
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Wednesday, June 2nd, 2010 AT 9:26 AM
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
Still would have been an injector. Ignition will act up under load most of the time, but as the engine warms up, it begins using the o2 sensor and other sensors, this is when a weak injector will start acting up.A cat converter will change the entire engine, not just one cylinder, same for the o2 sensor for the most part. They control the entire mixture, which will rarely change any one cylinder
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Wednesday, June 2nd, 2010 AT 11:48 AM

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