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Anyone had this problem? My 2001 XJ for the past two years(cronic) has a problem of misfiring cylinder #4 in particular and all cylinders in general. I have the 4.0L six with an automatic transmission. No mods to the enginge outside of a K&N air intake. It may go three months without happening(intermittent) and then happen every day for a week. Here's the senario. You get in when it's stone cold the engine starts fine and you drive off. After reaching full operating temp(running fine at this point), you stop at a convenience store or fill up for gas and have the engine off for say 5 minutes. When you start it again it fires right up but the idle is rough, the check engine light comes on and you get a "cylinder misfire"(#4) code or "mutiple cylinder misfire" code. You put the jeep in gear and drive off the engine smooths out and runs fine. But you have to clear the codes to put out the check engine light. Now if you stop for 30 minutes or longer it will not happen! I've already changed the spark plugs and the coil pack(no wires). This sound familiar to anyone? Thanks for listening.
Sounds kinda like a crank shaft position sensor problem. I had a similar problem a few moths ago with an autozone sensor. I put in in the sensor and every now and then it would set a code with multiple cylinder misfire on 1 or more of the cylinders, So I took that sensor out and installed another and so far so good.
You get in when it's stone cold the engine starts fine and you drive off. After reaching full operating temp(running fine at this point), you stop at a convenience store or fill up for gas and have the engine off for say 5 minutes. When you start it again it fires right up but the idle is rough, the check engine light comes on and you get a "cylinder misfire"(#4) code or "mutiple cylinder misfire" code.
This is symptomatic of the well-known heat soak issue common to 2000 & 2001 XJs with the 4.0. There has been a lot written on it; search 'heat soak' for more information.
You put the jeep in gear and drive off the engine smooths out and runs fine. But you have to clear the codes to put out the check engine light. Now if you stop for 30 minutes or longer it will not happen! I've already changed the spark plugs and the coil pack(no wires). This sound familiar to anyone? Thanks for listening.
Unfortunately, you're kind of screwed. There is no real fix for it that works, just ones that make it less pronounced.
The best method of dealing with it that I've found is as follows:
- Start the XJ. Check the temperature gauge once the engine is running.
- If there is no stumbling, drive normally.
- If there is stumbling, chances are the temperature gauge will be reading above 210degF (but hopefully not in the oh-crap-it's-overheating zone). If this is the case, let the XJ idle - and I mean idle; don't touch the accelerator - until the gauge gets back down to or just under 210degF; by this stage, the stumble should have cleared itself and it's OK to drive again.
Jump on the highway and run it up to full operating temperature--at least 20 minutes.
Pull into your favorite fast food restaurant, shut her down, open the hood fully, go inside and have your favorite repast. After a full 30 minutes of cool down go out and start the XJ--is the problem gone or substantially better? If yes, then congratulations, you have heat soak.
Other possible problem could be synch sensor alignment.
Does sound like heat soak, although heat soak usually hits cylinder 3 harder than cylinder 4, but it still sounds heat soak related. Try the experiment Joe recommended.
Camshaft sensor position alignment is a good idea for the 00-01 with weird misfires.
Be sure that you don't have BOSCH plugs in there. The 4.0 generally speaking doesn't do well with them. The NGK spark plug is the best plug for the distributorless coil pack system used on the 00-01.
Mine is even more intermittant, I may go 6 months with no problems. Then all of a sudden I get the 3&4 cylinder misfire code.....now I know what to start looking at. Good info.....
IF you have heat soak the factory TSB is to wrap the number 3 injector in insulating material. FAIL.
IF you confirm heat soak your best be lies in adding an aftermarket timer to the auxiliary fan so that it runs for 3-5 minutes after the ignition is turned off.
Camshaft sensor position alignment is a good idea for the 00-01 with weird misfires.
Be sure that you don't have BOSCH plugs in there. The 4.0 generally speaking doesn't do well with them. The NGK spark plug is the best plug for the distributorless coil pack system used on the 00-01.
I've been dealing with this issue since last August in my wifes 01'. Funny thing is that the jeep ran perfect up until I got a #3 misfire and bank two 02 sensor in Aug. I pulled the plugs and found that they were the factory oem Champion Coppers (looked terrible), so I replaced the plugs, the 02 sensor and the jeep seemed to run fine again. The very next day It threw another CEL, but seemed to run okay with intermittent problems that I played off as possible heat soak (never before experienced in this jeep prior to Aug).
Finally, the the Jeep got to the point where it was misfiring bad daily, so I've spent the past four days chasing a random misfire #2 and #6. p0302-306-300. I was talking to the guy at O'reillys and told him that I had already replaced the plugs and didn't thing that would be the issue. He said are you running platinums and said yes, Bosch Platinums. His answer was "there's your problem". I decided to grab some cheap Champion Coppers and went home, change them out and just like that the Jeep ran like a raped ape again. I drove it around all evening for several miles turing it on and off with zero issues. Ran perfect
Problem solved right? Not so fast. The wife drove the jeep to work this morning (30 miles) and it ran great. This evening on the return trip just a few miles from work it stumbled again at idle. She said that she got onto the freeway on ramp and bam, stumble, flashing cel, again. I'm at work so my son checked the coil pack plug to make sure it didn't come loose, but it's on and tight.
I can't imagine that the jeep would run so good for that period of time and then something else going wrong. My quess is that it has to be related to the coil pack or plugs. I will look into it tomorrow and report back.
Long story short. Don't install Bosch plugs!!! That was very convincing.
Update; I test drove the Jeep for 37 miles today with no change in status. The CEL that appeared yesterday while the Wife was driving home cleared itself today after a few minutes of running. I ran the jeep pretty much all day, letting it idle as well as test drove. No heat soak was present and I couldn't even check the CEL because it cleared itslelf.
Typical Jeep stuff
I used to get worked by heat soak and intermittent misfires :helpme:
Just keep everything stock and use the OEM stuff you'll be much better off
The local Jeep dealership recommended and performed TSB#18-031-03. This includes installing #56028371A Sheild, Ignition Cable and updating the computers software. It did seem to help quite a bit, but did not eliminate it entirely. I'm going to look into hooking up the Efan to run for 2 to 3 minutes after shut down of the engine. Hope you all have better luck resolving this issue. Thanks to everyone for the input.
i had that problem on one. in my case, the previous owner had the injectors out to clean them, and when he put them back in, forgot the to put the clips on. injectors were held in by gravity lol
Check the ignition coil resistance before replacing. Additional "valuable" information: I purchased two coils and bolted them together and installed them in the factory location. Now if my coil fails, one could simply switch the ignition lead to the second coil. Voila!
I have the 'heat soak' issue, mine is a misfire on #3, only does if its warm outside and the jeep has reached operating temp and i stop for a few minutes its will run like dog poo for 30-45 seconds and then everything is fine. Im going to try DEI Reflect-a-GOLD, im going to wrap #3 and 4 injectors and my intake manifold with it, I will post up my results.
