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HELP! heat soak problem

D

Dragonlich1961

NAXJA Forum User
Location
Ohio
Apricitate any help i can get as my dd is down now and it's my only ride.

Problems, cold starts fine and will get all the way up to temp. eventually it will start to sound like it misses occasionally then start to stumble and idle extremmly rough almost stalling. sounds like an old clapped out jalpoy. it does this at idle and at speed. very rarely will and throttle imput help. usually it results in the engine feeling like it takes a nose dive. putting it in gear makes the problem worse. vechile will not hot restart. it will crank and occisionlly cough. Use to do this at idle while waiting at a light only and the problem has progressed worse to happening at highway speeds.

no dtc's are pressent and chech engine light does work

1994 jeep xj 4.0 auto.

Chris
 
Last edited:
sounds more like a wiring issue or failing injectors. try wiggling wires while its doing it to see if it gets better or worse. when was the last time it had a tune up? plugs, wires, o2 sensor?
 
Tune up was 25 k ago. It will drive fine for a 10 mile hike down the highway. Once I take an exit and slow down it throws a fit. Vehicle has 141k on the odo
 
Gauge reads 190-210ish. I can't hear an leak from the intake,. Vehicle will idle for every with the hood open but eventually it will have an issue when closed.
 
I had an ignition module do the same thing. The owners took it out and had it bench tested, twice. It only failed when it was hot, but did that with the hood open or shut.
 
My guess is something in the electrical system like a crank sensor, TPS sensor, or coil is failing when hot. The sensors tend to bench test fine but will fail when hot.
 
Progress, thinking the usual cps failure. I purchased one. Got most of the way home before she threw her fit.
Tow strapped her the rest. Got home she started but then shortly threw a fit. Fine put the sensor in. Started up and idle for half hour hood closed no problem. Will test tomorrow on highway. Changing one on a hot engine sucks.
Chris
 
Replaced cps. No change. Replaced tps cleaned IAC and replaced leaking exhaust manifold (4 cracks). No change. When trying to restart hot after dieing it sounds like it's got no fuel or spark. Checked for pressure at rail by hitting the release button. Pressure present. Checked spark by pulling coil and grounding using a plug. Weak red-orange spark. New coil now installed. Hope this works
 
Could the 1994 XJ be probed for errors even though there is no CEL? At this point I would take a look at the oxygen sensor. Some time ago my XJ did just that. It would start and run fine when cold then revolted when it is at normal temperature.
 
Perhaps while running. But it won't restart once it revolts until it cools. It spits and sputters like no fuel or spark . I've got fuel up to the rail. So it's either not firing the injectors, all of them or is not sparking. Spark was easier to check. I've let it idle for 45 mins in a parking lot with hood closed and it never skipped a beat.
 
Try replacing the coolant temperature sensor, it should have two wires. This was my problem in an 89 4.0L and mine is in the block water jacket, yours I believe is in the thermostat housing or on the drivers side block. Many on here ignored this advise in the past but it's what fixed mine instantly. Good Luck
 
Jeff/Alaska said:
Try replacing the coolant temperature sensor, it should have two wires. This was my problem in an 89 4.0L and mine is in the block water jacket, yours I believe is in the thermostat housing or on the drivers side block. Many on here ignored this advise in the past but it's what fixed mine instantly. Good Luck
Click to expand...

This.



"Heat soak" is a myth.
 
ah. no codes are present curently. yes the light works, i can force a code to make the bulb work. i'll give it a shot, how would i test the sensor? pot of water and a multi meter?
 
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