My TJ hates me
- Thread starter Ccturley
- Start date
OK...
Update time.
Got the PCM Thanks Mark @Wranglerfix lol the label is a nice addition to the star power of her looks under the hood! PCM works perfectly, owever it didnt fix the root cause of the problem. Installed it and let it run up to operating temp didnt have any issues. Drove it a .25 mile ish around the block, stumbled like it was going to die lurched recovered (I expect this was in part due to it being a fresh PCM without stored run data) no more issue the remainder of the drive. Got it back to the driveway and let it run hood closed for 45 mins. then it died.
Overall I think there were some age/heat related wear issues with the PCM, but it seems it was not the root cause of the failure. Keeping the new PCM (awesome return policy btw) as other issues seem to be corrected. Something that I didnt suspect at the time as I had nothing to compare it to was the old PCM wound get really hat to the touch on the firewall side of the case. Even with the hood up resting on the windshield. The new PCM doesnt get hot like that, warm yes but not like the old PCM.
Still no codes.
Symptoms that have disappeared:
No more hard start, fires up every time.
Tach and Oil pressure gauge are back to acting normal.
no longer doing the stumble/recovery consistently very very random at this point and not nearly as severe.
Symptoms that still exist:
Dies after reaching operating temp of approx 175 degrees.
Friday drove and ran for 1.5 hours hood closed before it died. fired right back up ran :30 ish seconds then shut off did that 4 or 5 more times then started and ran for 30 ish more minutes before it died again. (called it a day since it was 9:30 pm)
Still very occasionaly stumbling a bit but recovers and doesnt repeat it like it was.
This morning:
Started right up idled great hit around 180 deg (monitoring on scan tool) and shut off. No sensor on the engine reads above 150 degrees (handheld digital ir thermo). havent tried a restart yet.
New symptom I observed last night:
Right before the engine would stumble it would "sound" like it was opening the idle valve to full and it would bog down and sound like it was laboring, when it would drop in RPM the interior lights would dim as expected then they would get brighter than normal (normal being what they would be if it was just sitting idling with the door open) then it would shut off. I hadnt noticed this before as ive mostly been working on it during the daylight hours. Last night it was starting to get dark and the light surge stood out to me. Thhis might have been happening this entire time and I just noticed it last night. Thoughts on that? Could I have a bad regulator on the alternator and that be whats causing this entire issue? GAuge reads just under 14 volts and the scan tool reads 13.5 with lights off, no accesories on. Scan tool doesnt show a voltage spike when the lights get brighter.
Passing thought, May not be relevent I have noticed that periodically the system will switch from closed to open slowly with long periods inbetween each switch while at operating temp. On other model cars Ive owned this is usually a rapid flip Is that a normal behavior for these jeeps? Also Both 02 sensors are sending data, Upstream is a little sluggish I do not remember ever replacing either of them. Could either sensor be breaking down inside and causing intermittent short to grounds and shut off the engine?
Im asking stupid questions because I have taken every step to achieve a competed repair but here we are. I am missing something, what is it?
Update time.
Got the PCM Thanks Mark @Wranglerfix lol the label is a nice addition to the star power of her looks under the hood! PCM works perfectly, owever it didnt fix the root cause of the problem. Installed it and let it run up to operating temp didnt have any issues. Drove it a .25 mile ish around the block, stumbled like it was going to die lurched recovered (I expect this was in part due to it being a fresh PCM without stored run data) no more issue the remainder of the drive. Got it back to the driveway and let it run hood closed for 45 mins. then it died.
Overall I think there were some age/heat related wear issues with the PCM, but it seems it was not the root cause of the failure. Keeping the new PCM (awesome return policy btw) as other issues seem to be corrected. Something that I didnt suspect at the time as I had nothing to compare it to was the old PCM wound get really hat to the touch on the firewall side of the case. Even with the hood up resting on the windshield. The new PCM doesnt get hot like that, warm yes but not like the old PCM.
Still no codes.
Symptoms that have disappeared:
No more hard start, fires up every time.
Tach and Oil pressure gauge are back to acting normal.
no longer doing the stumble/recovery consistently very very random at this point and not nearly as severe.
Symptoms that still exist:
Dies after reaching operating temp of approx 175 degrees.
Friday drove and ran for 1.5 hours hood closed before it died. fired right back up ran :30 ish seconds then shut off did that 4 or 5 more times then started and ran for 30 ish more minutes before it died again. (called it a day since it was 9:30 pm)
Still very occasionaly stumbling a bit but recovers and doesnt repeat it like it was.
This morning:
Started right up idled great hit around 180 deg (monitoring on scan tool) and shut off. No sensor on the engine reads above 150 degrees (handheld digital ir thermo). havent tried a restart yet.
New symptom I observed last night:
Right before the engine would stumble it would "sound" like it was opening the idle valve to full and it would bog down and sound like it was laboring, when it would drop in RPM the interior lights would dim as expected then they would get brighter than normal (normal being what they would be if it was just sitting idling with the door open) then it would shut off. I hadnt noticed this before as ive mostly been working on it during the daylight hours. Last night it was starting to get dark and the light surge stood out to me. Thhis might have been happening this entire time and I just noticed it last night. Thoughts on that? Could I have a bad regulator on the alternator and that be whats causing this entire issue? GAuge reads just under 14 volts and the scan tool reads 13.5 with lights off, no accesories on. Scan tool doesnt show a voltage spike when the lights get brighter.
Passing thought, May not be relevent I have noticed that periodically the system will switch from closed to open slowly with long periods inbetween each switch while at operating temp. On other model cars Ive owned this is usually a rapid flip Is that a normal behavior for these jeeps? Also Both 02 sensors are sending data, Upstream is a little sluggish I do not remember ever replacing either of them. Could either sensor be breaking down inside and causing intermittent short to grounds and shut off the engine?
Im asking stupid questions because I have taken every step to achieve a competed repair but here we are. I am missing something, what is it?
You could remove or unplug the O2s and force it to closed loop (right, I always get closed and open confused) and see if that helps.
I recall a post where someone had a bad clockspring shorting the 5v bus to ground...but it sounds like you tested this.
You cleaned the IAC...have you verified it's working...kinda stupid since it idles...so probably not that.
Maybe a smoke test for kicks and giggles? I did mine the other day and figured out my throttle body gasket was long gone and I had a couple leaking injector o-rings...which was interesting because they were new and installed with grease.
Maybe time for a compression test?
-Mac
I recall a post where someone had a bad clockspring shorting the 5v bus to ground...but it sounds like you tested this.
You cleaned the IAC...have you verified it's working...kinda stupid since it idles...so probably not that.
Maybe a smoke test for kicks and giggles? I did mine the other day and figured out my throttle body gasket was long gone and I had a couple leaking injector o-rings...which was interesting because they were new and installed with grease.
Maybe time for a compression test?
-Mac
I Haven't don't this yet, but to answer your question, Closed loop is when it switched from stored parameters to live feed from the upstream. Open is when its reading from the stored data.
yea you posted this nugget already and I checked into that. had no effect.
IAC is functioning in real time, movement on compresspr activation. back probe reads normal fluctuations and it idles like a champ.
This would send me down the road of bad fuel economy, rough idle, possible misfires, poor engine performance. I dont think that a leak in the intake system would cause this specific issues im having. Ive seen odder things in my career.
This isn't a mechanical issue. no misfires, loss of power, poor performance etc that would be associated with a leaking cylinder. The main symptom is it just shuts off, like you turn the key.
The most frustrating part is, I just changed the plugs. that's it. Wasn't trying to fix a problem it was just time to replace them.
I pulled the dash apart and had a look while I was waiting on the pcm. Wiring is in pristine condition.
Sorry if i missed it, if already mentioned - since this all started with a simple tune-up. Is it possible that the plugs/new parts you installed were faulty? Cracked/missing electrodes/ceramic, etc?
Longshot but maybe/Might be worth reinstalling your old plugs/old parts and letting it idle?
Last edited:
So the TL;DR version is that I have tested all of the "new" parts against the old ones. When the second napa CKP died, literally lasted like 10 cycles of start and die before it threw no crank signal at pcm codes lol... I put the original back in and it started. I then ordered a replacement Mopar which is whats installed currently. I put the original cam sensor back in and it didn't make a difference in the symptoms, but it is showing signs of physical breakdown so I elected to keep the replacement installed. Solid scope wave form from it while running. Swapped the coil back to the original and it actually increased the run time it takes before the issue starts up. The coil is also a Napa product. So i'm assuming at this point that its a junk "new" part. I havent put the old plugs back in as the replacements are the exact same champion OE copper resistor. (changed every 30,000 since I bought it in 2000). That and they went out in the trash last week =(
So heres where we're at:
New PCM
New Mopar CKP
New Echlin CPS
Old coil rail
New OE Copper plugs
Symptoms Fixed:
Tach and Oil pressure gauge erratic behaviour
Hard start
Crank no start
Consistant Stumble/recovery at idle
Random Engine shut down.
Improved but still there symptoms (happens a lot less frequently):
Engine now shuts off Consistantly the first time around 150-180 degrees will immediatly restart and might run an hour, might run 5 seconds.
Small putts (almost like a backfire through the intake acts like a timing issue) very random and seldom happens.
New symptom:
Interior lights will dim then get really bright right before it shuts down.
Engine:
Idles great, when it runs has all of its power and full throttle response.
Is not overheating
Does not spit, sputter, chugg, lurch or drop out under load while driving
Fuel Pump:
50 PSI at rest, no pressure loss.
Idle 50 PSI
WOT snap 47 PSI.
Electrical:
I have deloomed the harness and checked every sensor wire coming from the engine. Continuity with little to no resistance from plug to PCM
Visually inspected all the wiring, checked for splits crack or breaks, found none. Tugged on any suspicious spots in bends etc did not seperate wire.
I have opened ground splice glue bond cleaned and soldered splice joint.
havent opened the 5V butIm getting a solid signal at all sensors
Checked injector pulse with tester, consistant
I have removed the braided ground strap, replaced engine block loop with new connector and soldered. Scrubbed patina and dirt from braid... Shiny fresh and like new. Buffed body points.
Buffed B- to body connection
Buffed B- to block connection
less than 1 ohm resistance from B to loop on main Ground wires No corrosion or breaks.
Pulled rear B- break out lead and checked for breaks/damage to fuel pump. In good condition.
Physically shook the shit out of the harness and can not induce a fault.
Tapped on Old PCM, CPS, IAC, MAP, TPS, IAT, CKP could not induce fault
Tapped on Distributor plug no effect.
Checked Ripple from alternator, scan tool diagnostic test function. Came back nominal.
Im desperate and cant believe im looking at this in the rare off chance its the problem stuff:
Checked wiring harness under dash, Everything is in place and factory wrapped. No rub through.
Unplugged the clock spring, had no effect
Under dash grounds, all clean and in perfect condition
Pulled lock cylinder, inspected mechanism and switch. Lock cylinder is a little worn but nothing stood out.
Checked Neutral/Clutch safety switch, good.
I know I saild TL;DR lol
Bad upstream O2 sensor can cause all sorts of issues once warmed up, right?. How does the PCM communicate with the O2 sensor?
Also plugged pre-cats/cats can cause issues, too, right?
Also plugged pre-cats/cats can cause issues, too, right?
does it do that lights dim/bright thing *every* time before it dies? That feels like voltage regulator, right? Also, I would’ve expected to see ~14.4V when running, not 13.5V.
They can. although i haven't personally run across one that causes the engine to just shut down. its certainly possible though that theres a short thats causing issues. they are heated 02's so the element could be the culprit. once I get back to it in a bit I am going to unplug the upstream and see if I can force it into open and make it read from the cold start data.
The cat has crossed my mind, but typically with a plugged or restricted cat it give symptoms of loss of power, sluggishness etc which I do not have. It's not off my radar but the exhaust is original and an inspection would more than likely require a gut off to get it apart. Ive already sunk right at a grand into this at this point and my wallet says hold on bro last resort lol.
Yes, which is why its on my radar now. 12.8 V - 13.8 was the spec i found on min to max regulator output. that could be wrong, but its been my experience over the years that 13.5 -13.8 while running is a good number. This is the bane of not being in the shop anymore... I don't have access to Mitchell anymore lol. I'll confirm what the regulator is "actually" outputting when I get back on it and let you know. I'll be honest if it turns out to be a bad alternator causing this issues i'll be relieved and happy but i'm gonna blow that dude up...
You've covered everything extremely well, and still have the problem. So what about other possible culprits getting hot and failing, perhaps just for a moment: battery temperature sensor (if your 2000 has one), Automatic Shut Down Relay, Fuel Pump Relay, etc. Replace a relay with a jumper and see how long it runs?
I don’t think the voltage regulator is your issue since you replaced the PCM if I’m not mistaken, the voltage regulator on these is not in the alternator. It’s part of the PCM. I would test the actual output of the alternator though, I suppose it’s possible that it’s dropping off once it heats up and then not putting out enough power for the PCM to regulate properly.
I Tried a jumper the ASD early on as I thought that might be the issue it didn't effect any change. I haven't jumped the fuel pump but ill try that and see what comes of it. I think it dies have a battery sensor but I'll have to check for that because honestly, im not sure.
Thanks guys.... this has reminded of one of the reasons why I retired lol ugh... I hate this shit.
Maybe I missed it above so if you’ve done sorry. But another member on the forum was having problems after a tune up. They ended finding out one of the new plugs were bad and replaced it, everything went back to normal.
Howdy neighbor.I can't contribute to a solution for you but want to welcome you to the forum from Jackson county Seymour area.
So... Decided to start from scratch with the harness. Pulled it out of the jeep yesterday retraced every step. Again couldn't locate any broken or damaged wires. Taped it all back up re installed it. Bought another new Cam sensor just for shits and giggles at this point. started on it this morning finished buttoning things up installed new sensor. Cranked it it fired right up like it has been since the PCM replacement. ran to about 150 then died. This time a p0340 cam signal at pcm code. Ok, seen this one before but it always had the ign coil ckt fault 1 2 3 code too. So... Decided to throw caution to the wind and I bypassed the harness ground (jumped back probe on ground BRN/YLO direct to PCM ground.) Fired right up and literally ran for an hour without any issues. Thought damn I might have found it. Then I shut it off went inside to grab a bite, 30 ish minutes came back outside wouldnt start. (crank no start) Checked codes p0340. Swapped to the other (old,new) sensor. Fired right up has been idling perfectly for 35 minutes now. At this point im not calling it fixed but I atleas feel like Ive got the issue isolated at this point.
Are these cam sensors really that finniky when it comes to heat soak? Whats your thoughts on that. Ive looked for a mopar version of the cam sensor no one seems to have any in stock any thoughts on finding that part in Mopar?
First time Ivenfelt like the lights at the end of the tunnel here.
Are these cam sensors really that finniky when it comes to heat soak? Whats your thoughts on that. Ive looked for a mopar version of the cam sensor no one seems to have any in stock any thoughts on finding that part in Mopar?
First time Ivenfelt like the lights at the end of the tunnel here.
Similar threads
