Engine stumbling

[brissiexj]

I have a problem I am chasing with stumbling engine. Motor runs fine, then after braking sometimes it stumbles like running on 4 cylinders. Pull over and turn off engine, wait a few minutes then start again and runs fine. This is very intermittent and sometimes doesn't do it at all. Cleaned carbon out of carb, changed MAP sensor, TPS and IAC. Any ideas and what to check next?

 

[brissiexj]

Also replaced spark plugs and coil.

 

[phydeaux33]

I have a problem I am chasing with stumbling engine. Motor runs fine, then after braking sometimes it stumbles like running on 4 cylinders. Pull over and turn off engine, wait a few minutes then start again and runs fine. This is very intermittent and sometimes doesn't do it at all. Cleaned carbon out of carb, changed MAP sensor, TPS and IAC. Any ideas and what to check next?

Year, Engine, and trans?

 

[brissiexj]

Year, Engine, and trans?

Sorry, 2001, 6cyl. Auto trans.

 

[Tim_MN]

Occasionally my 2000 will develop a stumble, a bottle of Techron injector cleaner clears that up. The in-line Jeep 6 cylinder motor is not know for a smooth idle.

The coil rail is hard on spark plugs, if you are using a basic spark plug replace them every 36,000 miles. I prefer platinum plus. Autolite AP-985 or Champion 3034 which are both an excellent choice for a single-tipped platinum plugs.

If the symptoms persist, look at the Idle Air Controller.

 

[asymptonic]

Heat soak?

 

[Tim_MN]

Heat soak?

Heat soak is a hot starting issue, and not a rough running issue.

 

[brissiexj]

Occasionally my 2000 will develop a stumble, a bottle of Techron injector cleaner clears that up. The in-line Jeep 6 cylinder motor is not know for a smooth idle.

The coil rail is hard on spark plugs, if you are using a basic spark plug replace them every 36,000 miles. I prefer platinum plus. Autolite AP-985 or Champion 3034 which are both an excellent choice for a single-tipped platinum plugs.

If the symptoms persist, look at the Idle Air Controller.

Already replaced the idle air controller, next step will probably be replaced the injectors.

 

[Tim_MN]

Replacing the injectors seems a bit rash. I would use Techron with the next 2 gas tank fill-ups and see how that goes.

Any engine sensors that are not genuine Jeep are suspect.

Inspect the injector connectors for corrosion and bent or pushed back wire pins, and inspect the injector wire harness for degraded/chafed/melted wire insulation.

My 1998 has the the original injectors and +290,000 miles on them.

 

[asymptonic]

Heat soak is a hot starting issue, and not a rough running issue.

Gotcha, my 98 isn't prone to it, so I didn't know.