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Intermittent Stalling Help

rasband

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Leading up to this I had no obvious signs, and wheeled last weekend without issue (thankfully).

I am getting intermittent stalling that I just can't figure out and haven't gotten a consistent CEL (I believe one was a red herring - a misdirection, which we will get to in a minute).

So far (with tests between each change that included parts)

* First Stall
* P0457 - replaced my OEM locking gas cap with an OEM non locking
* More stalls
* Replaced the Crank and Cam sensors (both were replaced last fall with the same issue... I had them in the bin in-case the others weren't MOPAR (these were originally done by a shop last year)
* More stalls
* Replaced all 4 O2 sensors (crossed my mind since a month ago I got a few O2 warnings)
* Cleaned the Throttle Body (idled with light sprays in the body and IAC)
* drove great all Thurs, idle felt smooth - one stall
* Friday I run out to get to the tire shop (I’m supposed to get 33s this week), stalled out on the way. This time when I started up after removing the key it would sometimes start and just sputter out. After a while of trying this I got the P0038 family of codes (typically meaning the cat system). However I’m not convinced of that given the dozen restart attempts immediately proceeding.
* Traced all wiring to look for shorts
* Checked all the grounds I can find
* Unplugged and re-plugged most connectors
* Blew into the EVAP line to check for clogs (at the solenoid in the bay on the cruise control bracket)
* Switched around relays to check for them going bad
* Checked all the fuses in the cab and engine bay

My last thought is maybe the fuel sending unit - however since it's an intermittent failure the pressures hold fine.

I’d rather know what’s wrong than keep guessing and tossing money at it but I’m not getting any new codes as I keep trying to drive it.

I do have a few parts in bound for the shelf in case they go out of availability and for planned work this fall (TPS, new Bosch Fuel Pump, Autolite Iridium Plugs).

What else should I look at? What else can cause the engine to just shut off?
 
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rasband

rasband

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I had to get the LJR home, so I was able to clear the codes and it drove fine. So that seems to me that it's some sensor that is tripping and the car decides it shouldn't be able to run normally. However that's just a guess.
 

Chris

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I don't think the stalling would have anything to do with the evap system. It could be a vacuum leak, though with a vacuum leak it would probably run consistently bad, not just sometimes.

Does it happen every time you drive it, or just randomly?
 
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rasband

rasband

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I don't think the stalling would have anything to do with the evap system. It could be a vacuum leak, though with a vacuum leak it would probably run consistently bad, not just sometimes.

Does it happen every time you drive it, or just randomly?
It seems to be pretty much every time I drove since the issue started, other than that first day after O2 sensors.

I can’t imagine even a clogged CAT could cause it to just die so intermittently - and with 57k on the odometer it seems early.
 
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Chris

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It seems to be pretty much every time I drove since the issue started, other than that first day after O2 sensors.

I can’t imagine even a clogged CAT could cause it to just die so intermittently - and with 57k on the odometer it seems early.
You obviously used NGK sensors, right?

When my cats were clogged it didn’t die, but it ran like crap and had no power above 2500 RPM or so.
 
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rasband

rasband

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You obviously used NGK sensors, right?

When my cats were clogged it didn’t die, but it ran like crap and had no power above 2500 RPM or so.
Yessir:

NTK23018
NTK23159
NTK23160
NTK23158
 
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rasband

rasband

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I'm probably going to build this today once my wife is home and I can take the car to check a longer sampling.

 

Chris

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I guess that's a good place to start. I'd also say to keep driving it as much as possible, because at some point (hopefully soon), it is going to through a CEL.
 
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rasband

rasband

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I'm also going to do a backpressure test in the exhaust system to see if there are plugs there. Looks to be an easy thing to check.
 
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rasband

rasband

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I just tested the vacuum system to make sure it's good, attached in place of the brake booster - reads reliably 14-15 at idle. Seems like that system is fine, as far as I know that's one sign that either the system leaks or there is an exhaust blockage - neither appear to be the case here.

Another data point, I was able to drive it rather slowly around after getting my tires done and didn't see any issues. One issue was under load when I was trying to test if it was related to a faster acceleration. However a follow up attempt didn't repeat it reliably. Thinking back though, most stalls were at or just after an acceleration from a stop sign or light (other than the few from when I just let off the gas).
 
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rasband

rasband

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I missed this somehow in the FSM that I found while looking for the expected vacuum pressure.

I don't have a rough idle and would expect spark plugs to cause misses rather than stalls. But for the low price of $34 from rock auto for all 6 Autolite XP985 - seems like a good thing to do anyway. Also after pulling just 1 - it looks like they are past their service life given the tip's shape.

Screen Shot 2019-09-07 at 3.52.15 PM.png


IMG_2178.JPG
 
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rasband

rasband

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Tonight I do a quick round trip of about 10-12 min. I get close to home, hear the chime, and all the gauges in the cluster are zeroed out (gas empty, tach = 0, speedo = 0, voltage = 0, etc). I threw the ODB2 in before shutting off and it couldn't connect to the ODBII system. I shut the TJ off and back into the ACC key and get "U0155" - cluster communication error.

No idea where to go from here.
 

BeavisTJ

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I would install new spark plugs, specifically NGK ZFR5N. Not long ago I was trouble shooting a similar stalling issue with my TJ.

I was throwing many parts at without mu h success. New O2 sensors, throttle body sensor, crankshaft sensor, OPDA, fuel pump you name it I replaced it. Then after someone on the forum questioned what plugs I had in it and went from there. No more stalling.

It was difficult to diagnose as it was stalling intermittently and not throwing codes.

A special note to mention is the camshaft position sensor. Like most people will tell you get MOPAR sensors for the Jeep as they don't seem to work well with aftermarket brands. However I replaced the camshaft position sensor with a MOPAR and it ran worse than before. Apparently there is a NEW stock issue that doesn't play well with the TJ. So I'd recommend hitting up a wreckers for a MOPAR CPS.
 
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rasband

rasband

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I would install new spark plugs, specifically NGK ZFR5N. Not long ago I was trouble shooting a similar stalling issue with my TJ.

I was throwing many parts at without mu h success. New O2 sensors, throttle body sensor, crankshaft sensor, OPDA, fuel pump you name it I replaced it. Then after someone on the forum questioned what plugs I had in it and went from there. No more stalling.

It was difficult to diagnose as it was stalling intermittently and not throwing codes.

A special note to mention is the camshaft position sensor. Like most people will tell you get MOPAR sensors for the Jeep as they don't seem to work well with aftermarket brands. However I replaced the camshaft position sensor with a MOPAR and it ran worse than before. Apparently there is a NEW stock issue that doesn't play well with the TJ. So I'd recommend hitting up a wreckers for a MOPAR CPS.
Spark plugs are inbound still, I’m hoping that’s the cause.

I may put back in the previous CPS since it seems unlikely it would die in a year and the issue wasn’t fixed by changing it. But getting to a junk yard is a good idea to have more original spares.
 
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L J

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I would install new spark plugs, specifically NGK ZFR5N.
I've been running the plugs he ordered (Autolite XP985) for well over a year without issue.

Spark plugs are inbound still, I’m hoping that’s the cause.
At worst you'll eliminate a possible cause and you can't beat the price as cheap as they are from RockAuto with the current rebate.
 
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rasband

rasband

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Tentative first trip with the new plugs is a success, I’ll have to do more driving over the next few days to determine if it’s that simple.

I must have never noticed how rough it may have been running after feeling it with the new O2 and Sparks, it’s pretty noticeable.

Here’s the old ones for reference, they’re quite long in the tooth, but the wear looks to be pretty even and consistent - so at least I know the engine is running pretty cleanly.

661F57C1-D885-45DD-975D-6B1325B188D1.jpeg
 
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