pest code

so i have had a few issues over the past few weeks, the first being the fact that in any sort of moist condition the xj would die without warning, obviously fuel...air....spark right? but we as cherokee owners know differently. how ever i did check them all for good measure, it popped about 5 codes when it did this, multiple cylinder misfire, and a ignition module fail ect. i narrowed it down to the ASD relay, swapped it out all codes went away, fired right up, no worries right! of course its not that easy, not it keeps spawning a cylinder 1 miss code, i clear it drive it and its fine, however when i stop and shut it down let it sit while I'm in the store, come back and fire it it has a mild stumble/miss, more of a murmur or rough idle at best and the code comes back with a check engine, doesn't feel rough when driving only momentary and then its fine. no trace of an issue aside from a stained computer and a check engine. now heres the tricky part it seems to jump the temp up when it does it, not bad but enough to be noticeable. i pulled the ignition rail and either my meeter is off or it shouldn't be running at all buy what my meter is saying; .02 ohms and no change in reading at the crank. i spoke to a mech at the jeep dealer and he blew it off and immediately said PCM which i refuse to believe. all that being said, is there something i am missing, this is the only issue all other sensors and relays are good to my view. injector and plug are fine too. thanks in advance.

HH

... what year XJ? What motor? What transmission?

2000 4.0 aw4

The Hebrew Hammer said:

2000 4.0 aw4

Click to expand...

Well, almost sounds like "hot soak", TSB 18-031-03, except that is "supposed" to happen on cylinder three.

Try this--get her hot, pull into a mini-mart, open the hood fully, buy a soda pop and let it sit for 30 minutes with the hood up. Restart the engine--if the rough idle is missing, you have "hot soak".

The ONLY cure for heat/hot soak is a timer in the efan circuit that runs the efan for FIVE minutes after the ignition shuts off.

Post up what you find out.

that was one of my thoughts, but it seems a bit impossible. when it "heats up" after i shut it off and restart its barely at 210 but i will give that a shot, thanks for the thought. in regards to the "fan timer" how does it work, literally i know how but the physics of it I'm not understanding because if the water pump isn't running nothing is circulating hence the running fan would useless-ish unless its just to get air into the engine bay? please tell me if I'm crazy....no offense taken

I have a 2001 and am too familiar with the heat soak problem.

The issue is that the precat for cylinders 1-3 is directly under injector #3 and when there's no airflow heats it up to the point that I/you get vapor lock on #3.

Yes, when the engine's off the water pump isn't running and the water isn't circulating, but that's not the problem -- the problem is the superhot air rising from the first precat and overheating injector #3.

From what I read the answer is to let out the hot air when the engine is turned off. Vents work, so does running the electric fan. I've even seen reports of putting spacers between the hinge and hood, raising the edge nearest the windshield in order to let the hot air out there.