Swap throttle body from heavy and that other thing you got? I know dave was plagued with some weird crap with a chafed wire so maybe test the harness. How many miles on this thing nowadays?
I don't think a throttle body would have anything at all to do with it.
Only thing you might get is a vacuum leak.
When it cranks but doesn't run do you have spark, fuel etc.
I use a test light, and a noid on the injector, is it vapor locked?
Might be a temp sensor if it reading the wrong thing you can get those problems. A scanner should be able to read the temp. There is usually 2 sensors one for the computer and one for the gauge. If the sensor is reading colder than it is it will be in cold start mod basically having the choke on, and flood it. All the unburnt fuel in the exhaust might back fire.
Another thing might might be pug wires.
Wire can cross fire meaning spark go from from the wire that is supposed to arc and instead go to a different cylinder which could be the back firing.
The more compression the harder for the ark to spark, electricity takes the easiest path.
But you would probably have misfires when it is running.
Maybe it is time to drop it off at a shop if you don't want to keep wasting time and parts at it.
Also there has been more than one time that I got a brand new defective part.
You can read most of the sensors signals directly in real time with a graphing multimeter like a Snap-on Vantage which I have. Scanners have too much delay to really know the issue.
Friday nights I'm in my shop work on the buggy, your welcome to work on your XJ.
I also have a 97 XJ if you want to try swapping parts, but my XJ is a little tired too.
I think I remember unplugging the coolant sensor at rausch over the summer without issue. and I remember a trip before that you were having issues with it. As in the needle was jumping around. the only reason I remember is my Jeep did the same thing that same weekend on the way home and I swapped the sensor and now its great. But didn't you change the sensor already? part of me thinks you did. As for fuel pressure and a possible fuel pump, i remember testing it at rausch and we didn't have any issues. Doesn't mean it can't be intermittent. but I think when it was misfiring we were testing the pressure and it was fine. I was thinking vacuum leak like Justin said as well but i feel like that may be a constant issue? anything is possible.
Justin, could it potentially be a PCM? Ive seen intermittent problems like this be a PCM but I hate to just swap one out and hope for the best.
I dropped the Jeep off with justin last week and he spent a few nights on it...did a lot of trouble shooting, changed the fuel pump and IAC, and found an o2 was reading wrong also, when unplugged it would run better...the jeep is good to go again, been a long time comin...thanks for your help Justin and everyones input
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