Survey- For those with misfire issues

[Rusty Shackleford]

How does an O2 sensor get hot because of wiring? It's in the bloody exhaust manifold. The wiring may have gotten too hot but..........sounds fishy.

I have the whole story from the guy in the service department now. The O2 sensor was bad because the wiring harnesses got fried from being wired wrong. The bad O2 sensor caused my P0300 code. They replaced the O2 sensor and wiring harness, took it for a drive and it still threw the code. So they replaced the O2 sensor and harness on the other side. Apparently after the next test drive they determined that this fixed the problem. He also mentioned that they replaced a valve cover gasket ??‍ I’m not mechanically inclined enough to know how that’s related or how these things affect one another.

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[Rusty Shackleford]

Please DO update...

I'm wondering also... in most cases... If someone is unlucky enough to have a "unfixable" P0300 code Gladiator/Wrangler if it is usually revealed very early in the vehicles life, for example the first hundreds of miles up to around a thousand or so.... And in your case, showing after MANY miles if it is a legit fixable problem like a coil, spark plug, valve, cam, etc....

Update: 2 new O2 sensors, the associated wiring harnesses, and a valve cover gasket. I pick it up tomorrow so we will see if that actually fixes the issue. I am debating going the lemon law route and seeing if a 2023 JT is built better.

 

[ShadowsPapa]

There have been instances of the valve cover gasket leaking and causing the O2 sensor to get wet with oil, soaking the wires, and causing misfires due to inaccurate O2 readings.

What year is your JT? See below -

 

[Rusty Shackleford]

There have been instances of the valve cover gasket leaking and causing the O2 sensor to get wet with oil, soaking the wires, and causing misfires due to inaccurate O2 readings.

What year is your JT? See below -

I have a 2021 Sport S, MDH 033010. Here’s a picture of the write up on the worksheet:

 

[ShadowsPapa]

I have a 2021 Sport S, MDH 033010. Here’s a picture of the write up on the worksheet:

OK, you have a 2021 and a right side valve cover leak. That dealership needs to look at the document I posted. You possibly should have gotten the updated valve cover - it may leak again. Jeep has found a problem with the right side valve cover itself that can lead to leaks.

Model year 2021-2022 (March 2021, right in the middle of the 21 model year), right side valve cover leaks - I bet they owe you a valve cover.

 

[Rusty Shackleford]

Thanks for the info @ShadowsPapa helpful as always. I’m seriously considering just getting a 2023 and giving Jeep a second chance. It’s a devil you know vs. ? at this point for me. I definitely don’t want to be dealing with a bunch of issues out of warranty though. I noticed you traded one Gladiator for another. Is your newer one any better/worse?

 

[ShadowsPapa]

Thanks for the info @ShadowsPapa helpful as always. I’m seriously considering just getting a 2023 and giving Jeep a second chance. It’s a devil you know vs. ? at this point for me. I definitely don’t want to be dealing with a bunch of issues out of warranty though. I noticed you traded one Gladiator for another. Is your newer one any better/worse?

I traded mostly for the Selec-Trac transfer case, and because I was racking up miles (yeah, like almost 10,000 on this one is doing any better).
This one has had software and CANbus issues, the other one had zero engine or related issues. It was perfect in the drivetrain and engine. But to be fair - this one was resolved with a PCM update (weird misfire when hot, then a hot start 30minutes later) it hadn't done the CCDIFF learn process yet - cam/crank difference learn process.
So they manually forced it, sent what they learned to STAR, which was already looking into similar issues, and finally a TSB was released for a PCM update to handle that weird misfire.
They never put it on the ticket, but I can tell they were into the glove box area where the bus star connectors (?? terminology??) are and since then, no weird codes. It's just been working fine.

It's quiet and smooth as silk now. Was just telling a friend that when in town recently, I thought the engine had shut down, even though I didn't feel the tell-tale ESS wind down. It was sitting there very quiet, no motion, no sound. I looked at the tach - it was idling in gear at 600 RPM without a single quiver or sound.

So I guess, we'll see.
The 2020 had the steering gear thing, a saggy tonneau cover (they changed materials as this one isn't the fabric like twill or whatever material)

Both had some issues, neither real bad or killer defects that could have left me stranded.
I see higher voltages on this one when running, and the ESS always works, even after it's been sitting 2 days. Once I drive a couple of miles (or less, depending on weather) it works. Voltage is running higher than it did on the 2020. MAYBE they've made some tweaks to the battery charging rates? Just a guess based on watching gauges.

 

[rjogren13]

My 2019 3.6 just threw the p0302 with the same issues.....Any update on what your issue was?

Finally got it in to the dealer in early February. They replaced all six spark plugs. I asked if they reflashed the PCM or did anything else. Was told that they found a fix for a cylinder misfire that related to possibly bad spark plugs for my year range 2021 model (late 2020 build). since the plugs were replaced I have had no issues. start stop system never worked before, now it is working as the manual says it's supposed to. Not sure if they really knew there was a batch of possibly faulty plugs. But that is what's worked for mine.

 

[pbrevo64]

Finally hit me, so here we go:
Build date: May 2019 (050123)
Mileage when it first occurred: 67,810
How many times has it occurred: 4 trips, flashing CEL 20+ times
What exact codes did it throw: P0300, P0171 P2096 the first trip, last trip added P0133 and P0137
Is the issue on going? Y
If so, what has been done to try to solve the issue? Checked intake manifold gaskets, checked plugs and coils, replacing PCV and pcv tube (on order)
Was the issue ever fully resolved? In progress...


Recently replaced the rockers, lifters, and bank 1 cam, as well as spark plugs and a few seals as a preventative maintenance while it was torn down. It ran fine for a couple days, with the exception of a coolant leak coming from the heater core return hose on the passenger side, above the coil packs (the hose clamp was not seating properly). Fixed the leak, and it was running normal, but the next afternoon after 10-15 miles, it threw the P0171, P0300 and P2096 with "start stop unavailable" and a flashing CEL that went off after 10-12 flashes. The trip home it was a solid CEL. The next day, no issues around town (2.5 miles each way to work). Following day after 10-15 miles, it had the same ESS unavailable and intermittent flashing CEL, same three codes. Cleared the codes, and then that afternoon when I started it up, it flashed CEL for 10-12 flashes, had ESS unavailable and was idling rough. Drove home, and under load it was lurching, and idling rough at stops. The CEL dinged and flashed on 16 separate occasions on my 32 mile drive home, and pulling into my driveway it was sputtering. Tore into it today and all seals look in tact, but the MAP sensor was fairly oily, and the PCV was shot, even though it was just replaced 8500 miles ago.

 

[ShadowsPapa]

Finally got it in to the dealer in early February. They replaced all six spark plugs. I asked if they reflashed the PCM or did anything else. Was told that they found a fix for a cylinder misfire that related to possibly bad spark plugs for my year range 2021 model (late 2020 build). since the plugs were replaced I have had no issues. start stop system never worked before, now it is working as the manual says it's supposed to. Not sure if they really knew there was a batch of possibly faulty plugs. But that is what's worked for mine.

There was a TSB about the spark plugs. It impacted a 2021 Grand Cherokee we had.

 

[ChrisNLA]

Happened twice today (3rd and 4th times respectively for P0300 since new).

9,225 miles or so. Flashing SES light. First time it flashed for several seconds and went away. Second time it flashed for several seconds and then stayed illuminated solid. Did not seem to be running rough on either occurrence.

Both times the truck had sat for roughly 45 minutes since the last time it ran. Temperature outside was about 70*. Actually - all four total occurrences have happened in these approximate conditions. This also happened at 1,500 miles and 5,300 miles. The first occurrence the truck ran noticeably rough and then composed itself. The second time it did not run rough, only a flashing SES light that did not set.

Got home and took a minute to listen to the engine. Quiet. No valve train ticks or clatter. Absolutely the smoothest running engine in the driveway.

Snip from JScan after the second occurrence today:

 

[ShadowsPapa]

Happened twice today (3rd and 4th times respectively for P0300 since new).

9,225 miles or so. Flashing SES light. First time it flashed for several seconds and went away. Second time it flashed for several seconds and then stayed illuminated solid. Did not seem to be running rough on either occurrence.

Both times the truck had sat for roughly 45 minutes since the last time it ran. Temperature outside was about 70*. Actually - all four total occurrences have happened in these approximate conditions. This also happened at 1,500 miles and 5,300 miles. The first occurrence the truck ran noticeably rough and then composed itself. The second time it did not run rough, only a flashing SES light that did not set.

Got home and took a minute to listen to the engine. Quiet. No valve train ticks or clatter. Absolutely the smoothest running engine in the driveway.

Snip from JScan after the second occurrence today:

There's a TSB for that. It sounds like the CCDIFF issue mine had.
If it's fine when cold, then you drive it and it's thoroughly warmed up, then you park it and shop for 30-40 minutes, then get in and it misfires at low RPM, low speed, as if idling or moving slow out of a parking lot, then settles down, it's likely the same issue.
I can post more later - supper time.

 

[ShadowsPapa]

 

[ChrisNLA]

There's a TSB for that. It sounds like the CCDIFF issue mine had.
If it's fine when cold, then you drive it and it's thoroughly warmed up, then you park it and shop for 30-40 minutes, then get in and it misfires at low RPM, low speed, as if idling or moving slow out of a parking lot, then settles down, it's likely the same issue.
I can post more later - supper time.

Yea, I remember you having a similar issue and getting a resolution. I'm going to collect the info and will eventually make my way to the dealer.

Thanks.

 

[ChrisNLA]

Flashing light again today. Light didn't set, just flashed for several seconds and went away. Truck wasn't running rough or shuddering. Truck had been sitting all day at work - drove three miles to the grocery store and turned it off. Came back outside 15 minutes later, threw code as I was leaving parking lot. Gentle acceleration (2200 RPM when code hit), 83* outside with 52% humidity.

Quicky threw the VLinker in and opened JScan and screen grabbed the code, the freeze frame data, and the misfire numbers per cylinder. Also screen grabbed todays weather information.

Truck running silky smooth and quiet at idle.

Going to get better at this data grabbing. Making a folder on my computer for each misfire instance to put my screen grabs. After I have a small collection I'll take that and @ShadowsPapa TSB and see what they think.

Last time I took TSB's and good sound data to the dealer it was a painless experience.

Anyway - gonna keep driving until something starts rattling

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