My wifes 01 xj at first when i got it i did a tune up on it. put champion plugs in it. a couple weeks later it threw a cylinder 3 misfire code. than i changed the coil pack and it still threw the code. my next step was to swap injectors 2 and 3 it threw the code again in cylinder 3. i have ran this jeep for about two months with just the one clyinder misfiringand its been working just fine. just yesterday i was driving it back from central washington and it started to randomly misfire. so i pulled over shut it off and let it cool down when i started it up again the engine ran fine for about 60 miles than it started up again. today i changed the coil pack back to the original one that it came with, and not more than after 15 minutes of driving it started doing it again. so any insight on this problem would be a great help

 

there is a fix-it thing on this...cant remember exactly what its called
BUT it calls for a heat sleeve over the #3 fuel injector to prevent the vaporization of fuel in the injector due to heat from the exhaust manifold, which results in a misfire.
get some heat tape and wrap the #3 injector, should fix your issue

 

ok but its not only number 3 misfiring its also 4 and 5 and it shows a random misfire on the scan tool also

 

that sounds like a heat soak issue....fuel is vaporizing before it gets a chance to burn in the cylinders
wrap all the injectors and see what happens...
where in Washington are you located?

 

01 shouldn't have heat soak issue, but it is possible... https://www.cherokeeforum.com/f2/3rd...misfire-26952/

....have you checked the injector o-rings?!?!? what's your fuel pressure at the rail, engine on? should be ~49psi...look/smell for fuel leaking around the o-rings...if leaking, replace ALL o-rings, two per injector...make sure to rub a dab of oil on the o-rings so they don't rip...check fuel rail pressure.

 

i was on my way back from central washington i live in central oregon thanks for the tip i will try it

 

did a compression test today and found out it has a blown head gasket. it blown between cylinder 3 and 4.

 

How is it going now? I know you`ve probably heard a lot of horrible prices about getting this fixed professionally but it`s not all that hard to do if you are a fairly competent home mechanic.

 

Does anyone have any pictures of wrapped injectors? I'm just trying to understand this that's all. I keep getting my intermittent cylinder 6 misfire and I'd like to try this out. Also, which one do I wrap for number 6?

 

The injector for 6 is the one closest to the firewall. I have been looking for pics of wrapped injectors too.

 

If you pull the head for blown head gasket check head for cracks. 2001 4.0 engines with 0330 head are bad about cracking between 3and 4 cyl

 

How about the 99 heads?

 

I wonder if that insulation tape wrapped around the injector will help? I think I'm going to wrap all six injectors to see if that works. Any thoughts?

 

Well, I am going to do all 6 of mine too. My idle although it isn't all that great when cold, gets worse when hot, and I have changed everything. I am also going to do a compression test this week, if it will ever stop frickin raining here in FL....

 

I ended up buying a roll of heat tape yesterday(Advance auto $17) and wrapped all 6 injectors with a couple layers of it, I also wrapped the entire fuel rail while I was at it. I wrapped the crap out of the whole thing. I will update to see if my annoying idle miss goes away... I will put a pic in here too.