klargonthedestroyer

I'll do my best to keep this brief (update: I didn't keep it brief. I'm sorry.) I searched JK forum the last two hours and I feel all these issues are somehow connected so I want all of it centralized in one place. I have a 2013 JKU Sahara 6-speed I've had for four years. It's on about 4 inches of lift now, 35x12.5x17 mud terrains and factory 3.73s (6th gear virtually inaccessible on the highway.) Only once ever thrown an engine code at me which was 2 years ago, at which time I replaced a bad cam position sensor (bank 2 sensor A (driver's bank, sensor nearest firewall)). ZERO issues since then. Couple weeks ago I lent the Jeep to a buddy to take wheeling (first time I've done that; probably not happening again) at a park about 115 miles away. No issues on the drive down, or on the trails (light mud, moderate to heavy rock climbing). On the drive back it threw a P0018 (same code as before when I replaced the cam sensor) and went into limp mode. Pulled over, cleared the code, drove on. This cycle repeated itself 7 more times. Replaced the cam sensor the next day and cleared out all the trouble codes, which now included cam/crank corresponse codes, multiple misfires and about 8,000 other things. This is where it gets weird. Cold start began normally 8-10 seconds with cold idle, then rpm dipped sharply and come back up. Engine warmed another 10 seconds with idle slowly coming down like normal, then engine died. Restarted with almost exactly the same result, except the second dip was sharper than the first but it didn't fully die. When it recovered from the dip it threw three cam-not-corresponding-to-crank codes for three different cam sensors. My gut tells me this means the crank sensor is bad, so I swapped it for a new one. Cold start goes the same way again with the random rpm dips but it doesn't quite die OR throw any codes this time, despite the uneven idle. Everything goes as normal with engine warm-up after that, so I go for a drive around the neighborhood. Once everything is good and hot, it throws a P06DD at me. As I pulled over to check it I could also hear a bunch of clicking from my normally very quiet engine, possibly emanating from the head(s)? My buddy Google tells me the P06DD is an oil pressure-related code, which could account for all the unusual clicking. Oil now has about 225 miles on it, changed it about a week before my buddy borrowed it. I did use a different oil filter than normal (Wix maybe? I'm usually a Fram Tough Guard/Ultra Synthetic guy but the store was out of those this time) but using a different filter wouldn't cause some sort of blockage, would it? I don't want to panic and start replacing a bunch of components and have the thing tore apart in the garage if it's not necessary. Normally it's my daily driver but ever since this started I've been daily driving the '85 Chevy, which is fun until I have to replenish the fuel supply (not that a Pentastar on 35s with factory gears does much better!) I know this was a lot to take in but I wanted to present the totality of the circumstances to maximize the efficiency with which I get her back on the road. Thanks so much in advance for any input as to experience with this issue and/or likely solutions!

ballistik_monkey

i had a similar experience...ran fine for 15 seconds then rough idle, CEL flashing, etc. i posted all this fiasco on another forum (not sure if I can link it here or not) but it rhymes with Manglerforum. if you search google for "runs perfect for 20 seconds then rough idle" it should pop up.
mine might be a vastly different answer as far as repair, but in reading yours, the initial "runs fine then dies" thing was pretty close.

JonesboroJeep

2012 JK Wrangler Sahara with 204k miles. I worked through a few thousands of dollars of parts on Rock Auto and mechanics charges yet still had cam sensor codes. The codes jumped from one bank of cam sensors to the other from day to day. Eventually I noticed that the engine ran fine most of the time as I was driving but the codes popped up in certain areas of town. After some deductive analysis I figured out that the common denominator was deacceleration. I asked and checked around online and finally found that there is a newer failure mode exposed on high mileage Jeeps with the timing sprockets and chain. I dug further and found that the sprockets wear down faster than the chain and the idler tensioners wear down. Now you have slack in your chain because of the different wear items in the timing chain assembly. Well it is very interesting that I was getting most of my codes when I let off the gas so now the slack in the chain makes perfect sense. The slack in the chain changes the timing of the cams to the crankshaft so the computer reacts when the chain goes from tense to slack. I just had my jeep timing assembly rebuilt last week and now it runs like a swiss watch with no codes. The mechanic used a cloyes timing chain kit at Rock Auto and this was the best money I have spent yet on my jeep.

resharp001

I'm sure my thinking doesn't match the official company line, but I am all about helping people find the information regardless of where it is. Most of the time it is here, sometimes it is not. I post outside links from time to time if it gets the member an answer or can get them in the right direction. Sometimes I use bitly.com to create a shorter link like this -

https://bit.ly/3td1onc

The result being a bad PCM is interesting. Kinda sucks cuz obviously not something easily tested out in troubleshooting. I think for the OP, I wouldn't be shocked if this was the same issue. I've had cam issues before resulting in some misfires after replacing rockers/lifters, so have messed with some of this. What I find odd is the various codes being flagged. Though the cam phasers are sensitive to oil pressure it doesn't seem like see alot of people reporting cam/crank issues when dealing with the oil cooler/sensor/pump issues and vice versa. Toss in the start-up issues and it seems there is more going on here.

I try to think in terms of what I would do in this situation. I'm not one to throw parts at things, but I'm also not one to go to the dealer due to the overall headache of dealing with them, their schedule, and their ridiculous prices. ballistik_monkey's experience would sure have me thinking about a replacement PCM, weighing the alternative of dealer and/or endless troubleshoooting combined with the idea that if I succumbed going to the dealer they could likely end up replacing the PCM anyhow at a much higher cost. I'd probably feel better if I could corroborate these symptoms with one more person's PCM replacement.

Sixty4x4

Jonesboro has a good point which on high mileage Jeeps could be a good issue to investigate. Those timing chains, guides and sprockets don't last forever. And noticing on deceleration makes sense.

ballistik_monkey

thanks Russ! i didnt know about the bitly thing. (on a personal side note, you have always been super helpful on this forum...thank you! you rock!)

as far as OP. yeah, unfortunately, the PCM isnt one of those parts where you can just swap and see if it works or not....and they are pricey. regardless of what the dealer tells you, you cannot buy new....gotta go refurb.
step 1 in my book would be:
grab a Jscan and seriously dive in. get codes, read all your sensors, etc... see if you can get a more detailed picture as to what is going on under the hood.
one thing I learned after some digging: the PCM uses a canned tune for the first 12-15 seconds...after that it gets all the data from sensors and adjusts fuel trims, cam phasers, etc. so, you also have the chicken/egg scenario: is it the sensor that is bad...or the PCM interpreting the data bad...
Anyway...after months of pain, it was my PCM that was bad.

resharp001

Thank you. I really do appreciate that comment.

JonesboroJeep

Yes this is the new frontier as we are starting to see failure or wear modes on those with more than 175k or 200k miles. The 2011-2013 JKs have problems early on with the driver's side head misfires, but I think other items show up in high mileage. Many of the varied jumping cam and crank codes could be the timing chain slack once you get over 100k miles.

resharp001

I'm curious, can you ballpark what it cost to rebuild your timing? I'm nowhere close to that but interested.

klargonthedestroyer

Slight update: Did a computer reboot today (removed both battery wires and zip-tied them together for about 10 minutes to drain all the capacitors and stuff as recommended by my mechanic.) Although it doesn't throw any codes now during warmup it still does the rpm dip thing twice then runs normally. It does the usual "dry DOHC" start (loud lifters that quiet quicky once the oil gets up there) then once it gets hot it's as if the oil pump doesn't account for the oil thinning as it heats. Lifters start clicking like teeth chattering in January, and keep doing so regardless of rpm. Is this indeed an oil pump thing or something else?! Sure wouldn't mind being able to drive the Jeep once in a while but I ain't doing it if it sounds like the heads aren't getting any/enough oil!!