rsmwrangler

This showed up as pending codes for me yesterday. i was driving back home when i started feeling the Jeep missing a little, just giving light throttle at around 2000rpm at 60mph in 5th gear.
In some instances, the engine light was flashing confirming the miss, it never set a hard code, because the miss will go away, anyways, when i got home, i scanned for codes, and the only ones showing up as pending were P0152 and P0300, which is the generic one for misses.

I thought of replacing the driver side front O2 sensor since P0152 seems to indicate the sensor might be failing, it's weird because i check the voltage on both front sensors, and they seem to switching just normal, the Jeep was behaving normal later at night, when i took her out for a spin to check, i ordered one yesterday for orellys, picking this up today.
Yesterday night i tried to get the original one loose in prep to replace it with the new one, but my god i can't get my wrenches in there because of the intermediate shaft, and various hoses around it.

I rented an oxygen sensor removal tool, and i'm trying to figure out what's the best way to get the sensor removed ?
Should i loose the bolt in the intermediate shaft and compress that shaft down ? or do i need to take out the whole shaft ? i can't even get my hand in there to unplug the 02 connector from the harness, you have to be kidding Jeep :(

Please help, trying to learn as i go, but it seems the easiest things in the world for other vehicles are so complicated in this one, just thinking i need to replace spark plugs as well, as i have 83k miles, and what do i know, the dam spark plugs on the driver side seem to be under the intake, for crying out lod... lol

Then i started reading about people having heads replaced under warranty, but that seems to be related to specific code events, like a p0302 or PP305 etc ?
Maybe i should take it to the dealer, but given i have 83k miles, i don't have a kidney to donate to them,. damn it, i hope is not the heads needing replacement.

Appreciate the ideas.
Thanks a lot.

cjnomo

I'd start with diagnosing the cyl misfire first.

rsmwrangler

I'll do that tonigth, wife is driving the Jeep today and hasn't reported any issues.
I'll scan for misfire in each individual cylinder and take the Jeep for a drive to see if I can replicate the issue.

I'll also buy some fresh spark plugs and start there, I wanted to replace those anyways given the current 83k miles.

cjnomo

It's too bad she had to drive it before ur able to diagnose. I wonder if a better code reader would give you the exact cyl that misfired. I personally wouldn't drive it till you know what's up. Some people get lucky with no ill effects. Some people blow their engines (unnecessarily in some instances) and have to replace/sell because they didn't take the blinking cel seriously.

rsmwrangler

I did let her drive it because there were no actual hard codes present, the ones i listed were pending, but not set, meaning the condition existed, but didn't persist, which is why i'm puzzled, even more now, as the codes were gone on their own, wtf ??

Took the Jeep for a drive tonight, scanning current cyl misfires from cyl#1 through 6, and history of misfires from cyl#1 through #6, i was also logging total misfires and misfire rpm, drove around town for about 20 min varying the speed, thought yesterday when she missed, i was doing around 60mph in 5th, with rpm around 2000, and giving her very light throttle,
From yesterday observation, the dtc light flashed 3-4 times, twice, but the DTC condition never persisted, though i could feel her missing. the miss wold happen while on the throttle, and only in 5th gear while giving her a little throttle to accelerate while in 5th, which caught my attention, i would gas her up trying to make up speed, and she will accelerate normal, just not in 5th gear under light throttle, even the exhaust note was also changing as she was missfiring, my exhaust is not obnoxious, but i can hear it loud and clear as i have aftermarket mufflers.

Checked LTFT's and they're tight at -5+5%, no misfires, no DTC's, front 02 sensors are cycling between .1 and .9, Jeep is running as normal as she can be, WTF ???

When i checked P0152, it said This code indicates that the o2 sensor was stuck too high or in the rich position. The PCM monitors this voltage and if it determines that the voltage is too high out of range for too long, P0152 may set.

Read more at: https://www.obd-codes.com/p0152

i wonder if i had a little ground issue somewhere that cause the sensor to get stuck in high voltage? and this generated a rich condition? i did a little fire road on monday while raining, so while i wasn't mudding, she got pretty nasty everywhere, though i can't imagine that being an issue.

I'll drive her tomorrow and monitor everything.
Next week i'll check all my custom light wiring and see if i can solder some of the crimp connectors i did just in case, and see if i can change the spark plugs as well, i see if i can check where the PCM is located to make sure nothing in there is rusting or coming loose.

I also wanted to check ground at the chassis, and wonder where the 02 sensors take ground from ?

rsmwrangler

No issues on my 66 miles morning commute to the office today, lots of traffic, so a lot of stop and go
misses per cyl in normal range, and the amount per cyl is not even close to anything that will raise a flag in the PCM

normal_missfires by Wrangler RSM, on Flickr