P0068 this morning

Artsifrtsi

Artsifrtsi

I just wanna go wheeling...
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Just did a search, nothing popped up. I have a 2005 TJ X 4.0 6sp. Last night I drive the Jeep, and all was fine. Wife wanted my truck today, so I drove the TJ to work this morning, and the CEL lit halfway down the block. It still is running as usual, with no symptoms, just the CEL. When I got to work, I cycled the key 3 times, and it read P0068. I'll check for vacuum leaks when home.

History, about 2 months ago, I had P0022 (IIRC) for the TPS. I put in a crown TPS, cleared the code, and it has never returned. A few years ago, I replaced the master cylinder and booster, as the master was leaking into the booster. (slowly lost brake pressure after the Jeep fully warmed up. Had good pressure initially when stopping, but the pedal would slowly go to floor at a stop light). Back in 2011 it would randomly throw a CEL for Bank2 O2, but was random, and has not occured in the past 5+ years.

Any other things simple to check?
 
RMETeeJay said:
The fact that it's not running rough with that code is strange. Try going through this article for a list of things to check:
https://www.obd-codes.com/p0068
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Thank you for that, I'll look into it later and get back.

It was exceptionally humid out this morning, and the TJ rarely gets used... maybe it was just a trigger that held.
 
Things to check for vacuum leaks with a squirt bottle of water; spray around the base of the TB and the TB shaft, verify the MAP sensor boot that pushes onto the nipple of the TB doesn't have cracks. Possibly mouse nibbling on things.
 
Artsifrtsi said:
Thank you for that, I'll look into it later and get back.

It was exceptionally humid out this morning, and the TJ rarely gets used... maybe it was just a trigger that held.
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Vacuum leaks can sometimes occur with a cold start condition because the old rubber elbows get stiff. As the engine warms up, the rubber warms up and softens, and can self-seal small cracks. I suppose it's possible that a very small leak would be enough to trigger the code, but not enough to cause rough running.
 
Error presented again yesterday with a bang after not going into gear. Time to look into this more, as it’s time to start driving without doors and top sides...
 
After you check and if you find no vacuum issues or wiring issues, I would strongly suspect the Crown TPS. I have not had good luck with their sensors.
 
Ya know... it's damn hard to troubleshoot an issue that pops up once when you go to work, don't drive it for a couple weeks, need to use it for a week straight without the issues again... maybe it was just an excessive amount of humidity from all the rain we were getting...
 
I really hate the random nature of this error... 18 month of driving with no problem, through 2 winters and now the second summer, all sorts of weather conditions... the CEL came back yet again this morning on the way to work. I'm sure that when I start to troubleshoot it this weekend, it will disappear yet again.

It's odd that there are no other issues with the jeep other than the little light in the dash... no rough running; no noises, smells, vibrations, mileage, etc... Jeep was running just as well as it has been all along. There are 2 steep hills that I have to drive over, and I was able to accelerate over them in 5th, and could maintain speed in 6th.

You'd think that if it were cold related vacuum leak, it would have occurred when I was driving in 10*F weather, or in the 30's-50's... not when 70+...

Sorry, more of a rant than anything. I'll pick up some carb cleaner or ether and look for vac leaks this weekend...
 
I had the same issue for awhile: the dance with CEL. It would come and go. It has now gone for some time, more than a year, though I am always waiting for the other shoe to drop. I was never able to confirm any issue, but I did note that when the ambient temperature was above 85F and I was in the rev range above 2700, I would see the CEL come on at the next engine start. Always a misfire in number 4, but no amount of troubleshooting would reveal a problem.
 
Artsifrtsi said:
I really hate the random nature of this error... 18 month of driving with no problem, through 2 winters and now the second summer, all sorts of weather conditions... the CEL came back yet again this morning on the way to work. I'm sure that when I start to troubleshoot it this weekend, it will disappear yet again.

It's odd that there are no other issues with the jeep other than the little light in the dash... no rough running; no noises, smells, vibrations, mileage, etc... Jeep was running just as well as it has been all along. There are 2 steep hills that I have to drive over, and I was able to accelerate over them in 5th, and could maintain speed in 6th.

You'd think that if it were cold related vacuum leak, it would have occurred when I was driving in 10*F weather, or in the 30's-50's... not when 70+...

Sorry, more of a rant than anything. I'll pick up some carb cleaner or ether and look for vac leaks this weekend...
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Definitely try to smoke it out, you can make your own setup for cheap. If nothing comes up, and it really bothers you I'd look into a new PCM. There was never an actual recall, but lots of PCM complaints for the 05 & 06 TJs.
 
Artsifrtsi said:
Error presented again yesterday with a bang after not going into gear. Time to look into this more, as it’s time to start driving without doors and top sides...
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Elaborate on the bang and not going into gear if you will-
 
AndyG said:
Elaborate on the bang and not going into gear if you will-
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Hadn’t driven it for about a month prior to that, the clutch had stuck, and the bang was it releasing... had to start in heat to release it, normally I always start in neutral. Couldn’t get it in gear when running due to clutch not releasing.

That was 1 1/2 years ago. It went away, and was fine till this morning… I expect that it may clear again tomorrow morning on its own.
 
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Did not drive since Saturday (6-11), today first time since... no Light, and same driving dynamics. I'll be leaving with the JT for Moab on Friday, and will be gone a week... I'll build a smoker when I get back to try to find this intermittent issue.

A few questions on the smoke method though. Wouldn't the smoke find open valves and pass through the engine, not allowing the pressure to build enough to find leaks? What pressure is recommended to set compressor to? Any preferred port to use to connect the smoke box to?
 
Artsifrtsi said:
Did not drive since Saturday (6-11), today first time since... no Light, and same driving dynamics. I'll be leaving with the JT for Moab on Friday, and will be gone a week... I'll build a smoker when I get back to try to find this intermittent issue.

A few questions on the smoke method though. Wouldn't the smoke find open valves and pass through the engine, not allowing the pressure to build enough to find leaks? What pressure is recommended to set compressor to? Any preferred port to use to connect the smoke box to?
Click to expand...

I haven't done it myself yet (on my list!), but based on my understanding:

The smoke will get into the engine but not to an extent that it will avoid the intake passages.

Not much pressure is needed. As long as you've got some dense smoke, just a small amount of pressure will send it into the intake components. FYI, you can also send smoke up the tailpipe to discover leaks in the exhaust components.

The vacuum line on the brake booster is easy to access and you can make a good connection there. It's helpful to first remove the air cleaner hose and then use something to seal the top of the throttle body. I've seen some that fabricate a tightly fitting cap that includes a port to introduce the smoke at that location, which makes good sense to me.
 
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