MH1291

New to the forum and to jeeps as well. I recently had this issue stated in the title of the Cherokee dying while at an idle. i was in line at the dump for about an hour at idle and on my way to leave it died on me while I was waiting to leave. It wasn’t a hot day maybe about 60 degrees (I’m in Washington state) I started it again ran for a second then died again. I did this a few more times all with the same result of running for a second then dying. It wasn’t until I was able to get out of the line that it started to normal out then it started jerking and bucking until I got it up to a speed of about 35 mph then it ran fine and I was able to get it home. It was fine after that and been fine the little bit I’ve drove it. I’m just wondering what would cause that and how I can fix it?

I should also mention in the last year of me owning it I’ve replaced almost everything on it at least with sensors and what not here’s a list of what’s been changed.
Idle air control valve
throttle position sensor
temp sensor
map sensor
coil pack
spark plugs
plug wires
cap and rotor
distributor
crank position sensor
map sensor
throttle body has been cleaned
temp gauge sensor
head gasket has been done as well
thermostat

also the temp gauge wasn’t crazy hot either maybe just a tick past the middle but not much more.

just looking for some advice on what I should be looking in to?

Red1992XJ

I'm not an expert on this, but here's my .02 cents.

Sitting at idle like that for an hour, I wonder if it could have heated up enough to heat the fuel in the line to almost vapor lock. It may not have overheated the engine, but the engine compartment got hotter than it normally would have while driving and having air coming through the front. If it has not acted up since then, I would not be too worried, but don't take it on any long trips. Let us know if it does it again

MH1291

After doing more research that's what I was starting to think what was happening. It seemed like heat soak seems to be close to what is happening to me. From what ive read it seems like it could be a fault with something in my cooling system so ill probably consider getting new fans. Since this is supposed to be my daily/weekend wheeler and camping rig at some point not taking long trips is going to be a bummer. i need it to be reliable. Would any sort of fan upgrades be worth my time or even louvers in the hood be helpful to clear some of that heat out? I've done a little reading and the world seems to be pretty divided on these options

Dave51

That does NOT sound like a heat soak problem, as the issue only applied to 1999-2004 4.0 engines according to the TSB and anyway it pertained to rough idle upon restarts, not running poorly out of the blue (if I understand the onset of symptoms correctly).

MH1291

When i was researching i saw that it applied to those years and on restarts but it just seemed like it made sense because with everything else ive done im not really sure what else to do about or how to correct the issue?

Dave51

Yeah, if it's not doing anymore it's gonna be impossible to find. That said, it does sound like a fuel problem of some sort. I would get the fuel pressure gauge rental from AutoZone and see what that is. That thing's got a fuel filter right? Change that out if it's been a while. Have the injectors been cleaned? Probably should get some new O-rings before you yank the injectors out. Consider bad gas too. Check the electrical connections for the fuel system esp. the ballast resistor.

MH1291

fuel filter has was changed along with the pump back at the beginning of February (forgot to add that when I first made the post oops) and I did check fuel pressure at that time as well due in part to some issues with it not holding pressure. I checked my numbers just now with a harbor freight set that I have and with the key on I have 10 psi and at idle I had 34 psi with key off it slowly dropped. I've gone through about 3 different sets of injectors and a fuel rail that I got from a junkyard it used to not hold pressure at all and would get nothing with the key on until I changed it out. ballast resistor was also changed when I was trying to figure all that out early this year. I don't remember what the fuel pressure is exactly but I thought that was about close? I could be wrong ill have to research that. I don't know about the bad gas as it's driven regularly. I appreciate all the input anything past the injector cleaning I could consider?

Dave51

Haynes manual if you haven't got one:

https://cdn.xjjeeps.com/pdf/en-us/19...ice-manual.pdf

Robert Ottavio

sounds exactly like heat soak

MH1291

thanks for the link to the haynes manual that is quite helpful! my numbers didn't seem to stray too far from what is mentioned in the manual. I didn't do it with the vacuum line off ill try that again tomorrow. ill surf the forums some more for information on heat soak and what people have done to help it out.

Dave51

https://www.cherokeeforum.com/f2/200...roblem-255669/

This is the stuff to treat heat soak in the target audience. IDK if it'll fit 1992, but shouldn't be too far off and it's only 60 bucks.

Heat soak in the XJs was pretty much cylinder #3 in 2000-2001 (i.e., "mine") but WTH I suppose it can't hurt.

Dave51

The other thing I would consider is the crankcase position sensor got a little wonky. They can be thermally sensitive and would fit the scenario you described. Is your replacement CkPS a Mopar?

MH1291

https://www.quadratec.com/products/55125_0007.htm this is the exact crank position sensor I bought and installed. I know it's not Mopar but when I called various jeep dealerships in my area that said they couldn't get it anymore. so I figured that id go with that one because it matched the part number given to me by the dealerships. is this a good replacement for the stock one?

Dave51

The anecdotal reports (that means a bunch of guys) report that non-Mopar CkPS have issues. IDK what percentage that actually is, nor if you can find a Mopar 463828.

My personal experience is that if it's thermal sensitivity it'll get worse. The only way to be sure is wait till it happens again and check the output with a multimeter (you really need an oscilloscope but a mutlimeter should do if the CkPS has periods of dead).

MH1291

ill keep an eye on it I really wish I could have found a Mopar crank sensor. but from what I've seen it looks to be a discontinued part unless it's from eBay. ill just end up picking one up from there and having it handy I just hope its a true Mopar part.