Mystery Misfire... tried it all

I have a '01 xj, 4.0l with 84,000. I have random misfires, I have replace the ignition coil, plugs, wires, CPS, camshaft sensor, ran three part cleaners through it. Once I replaced the CPS it seemed better for a week then I got a bad idle and misfire, bogged bad. Then I put in a Camshaft sensor, seemed great for a week then when I was out wheelin after like an hour or two I turned the jeep off, then when I started it back up, it ran really rough. Any ideas where to go next? This is a nightmare. It all started in the spring when I got stuck and it sat in some water for a bit.
Thanks guys

I have them too, from sitting in a drive through to tooling down the highway, it will just happen occasionally, I have tried a lot too, but nothing seems to take them away. I have 223,000 miles though, its been doing it for about 30,000 miles.

Do you know what cyl is misfiring? have you had the E06 recall done? If so the debris shield that is installed with that recall directs a lot of heat at the #3 injector causing that cyl to misfire. You can put something aroud the injector the deflect the heat and it should correct your problem.

Here is what I heard you say... "It all started in the spring when I got stuck and it sat in some water for a bit." ...well the spring was 6 months ago...So I would start to worry about rust and corrosion problems... I would spend a couple of hours disconnecting, cleaning, prepping, and reconnecting every electrical and ground connection and sensor. If nothing else, when you are done, you will be sure they are not the problem, and if they are not the problem, you may find the real problem along the way...

It runs great when it's cold or warmed up, no issues except for when it got really hot. Could this be fuel injector related, with it only occurring when it's hot?

JEFF said:

Do you know what cyl is misfiring? have you had the E06 recall done? If so the debris shield that is installed with that recall directs a lot of heat at the #3 injector causing that cyl to misfire. You can put something aroud the injector the deflect the heat and it should correct your problem.

Click to expand...

So this manifold that redirects heat actually directs it on the fuel injector, that is heat related, I talked to a local dealer to check if the recall was done which it had. They said they haven't had any issues with the recall though. This was done in August '02, doesn't it seem like that would have come up before, or not because the previous owner might not have gotten it that hot?
Thanks

Northernxj,

Something to try. Check the color of the electrical wires to each of your fuel injectors and see if the proper color wire is hooked-up to the correct injector. On my 88XJ. I once incorrectly hooked-up the wrong color wires to my injectors, so the injectors were opening at the wrong time and out of proper sequence.

Best regards,

CJR

what kind of spark plugs do you have in it?

and how hot is REALLY HOT?

Double check the color codes on the injectors. They can easily be swapped. You can't tell where they go by their length.

chrysler changes over to ngk plugs to help with erroneous misfires. there is also a tsb to free up the exhaust valves. it seems they are sticking in the guides. and doing a cleaning of carbon built up on the valves too.