Rough idle after highway use

[Shwane]

After an while of highway use 55-70 mph my Jeep idles rough for a few minutes. Usually if I stop for gas or whatever. It goes away but I def have a cylinder misfiring after startup.

Could this be heat soak? I’m changing my plugs today to see if it remedies it.

2002 4.0 119,xxx miles

 

[AndyG]

After an while of highway use 55-70 mph my Jeep idles rough for a few minutes. Usually if I stop for gas or whatever. It goes away but I def have a cylinder misfiring after startup.

Could this be heat soak? I’m changing my plugs today to see if it remedies it.

2002 4.0 119,xxx miles

most of the time it is and insulating the number two and number three injectors is known to help. there are tapes and other products available for that I purchased a product at O'Reilly's.

 

[Chris]

Is it throwing any codes? If there is a misfire, it should be.

 

[Shwane]

No code. Or no visible code. It’s like one of the cylinders isn’t firing. But only for 30 seconds or so. Then it clears itself up.

I’ll try the insulation fix as well. I think I saw a tsb about that somewhere.

 

[KimsJeep]

I have a thread in here about this issue too. I was told the same thing about the injectors. I was also told I may be in need of a coolant flush and refill. I'm going to do the flush and refill as soon as all my parts arrive. Then I will probably buy the injector insulators.

Mine did this only after a long drive that I never turned the motor off. It was about 3 and half hours of driving. It started doing it after about the 3 hour mark. I was coming to a stop and that is when I felt it. It did it at almost every stop until I got almost home. Then it stopped doing it. I did take it for a drive later that day, but it never did it again. Also drive it back and forth to work, but in cooler weather, so far, LOL. Hasn't done it since. I'm still going to do flush and all, just in case. The flush is the only thing I haven't done as far as maintenance since I got my Jeep 3 months ago. Well that and I haven't done the injectors. I figured I would do those if I started throwing codes. I haven't looked into them but I am thinking it is probably one of the more expensive things to do So I am going with if it ain't broke, don't fix it modo on this one. LOL

 

[Jerry Bransford]

No code. Or no visible code. It’s like one of the cylinders isn’t firing. But only for 30 seconds or so. Then it clears itself up.

I’ll try the insulation fix as well. I think I saw a tsb about that somewhere.

There's a TSB (tech service bulletin) for that problem that directs the #3 fuel injector to be wrapped with the insulation linked to below. A single zip tie holds it on, the procedure takes just 2-3 minutes from start to finish.

https://www.amazon.com/gp/product/B007O3QHDK/?tag=wranglerorg-20

This is how it looks when you're done. This is mine and this cured my misfire that would start if the engine got a little hotter than normal.

 

[KimsJeep]

There's a TSB (tech service bulletin) for that problem that directs the #3 fuel injector to be wrapped with the insulation linked to below. A single zip tie holds it on, the procedure takes just 2-3 minutes from start to finish.

https://www.amazon.com/gp/product/B007O3QHDK/?tag=wranglerorg-20

This is how it looks when you're done. This is mine and this cured my misfire that would start if the engine got a little hotter than normal.

View attachment 87194

It looks like you have some other sort of insulation laying on top too? Mine doesn't have that. I think I will order the insulation sleeves you linked. It was suggested in my thread to do 2 of the injectors. (not sure which ones with out going back and looking for my thread on the subject. LOL)

 

[Jerry Bransford]

It looks like you have some other sort of insulation laying on top too? Mine doesn't have that. I think I will order the insulation sleeves you linked. It was suggested in my thread to do 2 of the injectors. (not sure which ones with out going back and looking for my thread on the subject. LOL)

View attachment 87280

That additional foil insulation under the fuel injectors was put there by the factory on my '04 model. It helps keep the heat from the headers aways.

It's the #3 injector that has the fuel vaporization problem which is the one the TSB says to wrap. I don't know about that being a problem for the #2 injector too.

 

[KimsJeep]

That additional foil insulation under the fuel injectors was put there by the factory on my '04 model. It helps keep the heat from the headers aways.

It's the #3 injector that has the fuel vaporization problem which is the one the TSB says to wrap. I don't know about that being a problem for the #2 injector too.

So maybe I will just buy one for now and see how that does.

 

[Shwane]

Thanks Mr Jerry. I changed the plugs and did that. Working so far.