2018 JL Wrangler 3.6 Multi-cylinder misfires, fuel soaked spark plug, poor fuel economy. Missing coolant. Root causes?

Gasbuggy

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P0300 is the only code you have?

Can you get the freeze frame data?

I don't believe I can with my handheld. Perhaps my HP Tuners could.

The P0300 is the only code. I've checked what is pending several different times and it's the only one that shows up in Pending or as the CEL code.

I didn't have much luck on the Wrangler forms but looking on the Gladiator forums, which has all the differences a JL would over a JK, this seems to be a rampant issue. There is a 100+ page long thread there on the "dreaded misfire code". https://www.jeepgladiatorforum.com/forum/threads/survey-for-those-with-misfire-issues.24853/

PCMs are being reflashed/replaced. Cams are being replaced etc.
 
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I don't believe I can with my handheld. Perhaps my HP Tuners could.

The P0300 is the only code. I've checked what is pending several different times and it's the only one that shows up in Pending or as the CEL code.

I didn't have much luck on the Wrangler forms but looking on the Gladiator forums, which has all the differences a JL would over a JK, this seems to be a rampant issue. There is a 100+ page long thread there on the "dreaded misfire code". https://www.jeepgladiatorforum.com/forum/threads/survey-for-those-with-misfire-issues.24853/

PCMs are being reflashed/replaced. Cams are being replaced etc.
Without that info and a proper diag, any info provided is a guess at best.

Are you in a position to do a full diag yourself?
 

Gasbuggy

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Without that info and a proper diag, any info provided is a guess at best.

Are you in a position to do a full diag yourself?

Educated guesses are what I was after, or more so hoping someone on here who has 3.6 experience might say "it's usually X Y or Z"

I won't spend alot of time under the hood because it doesn't belong to me and does still have powertrain warranty. However, I know I'm going to be the one going to and from the dealership when this gets dropped off/picked up etc and I want to maximize how productive the first appointment is so I'm not going back and forth multiple times.
 
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My bet is at least 1 cam lobe is wiped out. Took these from a fairly low mile 3.6L in our shop.

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JTK

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Like @Danno says, there's tons of youtube videos out there where people fire the parts cannon at their pentastar replacing coils, spark plugs, injectors, etc, when it's a mechanical problem causing a dead cylinder.

Sorry if I missed it, but If you crank the engine over in clear flood mode can you hear the cadence of a dead-ish cylinder?

If you do a scope/scan with an amp clamp knowing the firing order, this will pinpoint the dead cylinder as you're cranking it over. Like said, usually it's a rocker arm problem causing loss of compression in one or more cylinders.

I don't think top end parts are all that expensive or hard to come by for pentastars. A bit of labor of course. If it does need to be torn into and she wants to keep this vehicle, I'd invest in one of those Doorman all aluminum oil cooler/filter housings and swap that out while they're right there.
 
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Like @Danno says, there's tons of youtube videos out there where people fire the parts cannon at their pentastar replacing coils, spark plugs, injectors, etc, when it's a mechanical problem causing a dead cylinder.

Sorry if I missed it, but If you crank the engine over in clear flood mode can you hear the cadence of a dead-ish cylinder?

If you do a scope/scan with an amp clamp knowing the firing order, this will pinpoint the dead cylinder as you're cranking it over. Like said, usually it's a rocker arm problem causing loss of compression in one or more cylinders.

I don't think top end parts are all that expensive or hard to come by for pentastars. A bit of labor of course. If it does need to be torn into and she wants to keep this vehicle, I'd invest in one of those Doorman all aluminum oil cooler/filter housings and swap that out while they're right there.
I don't think he has a dead cylinder; most likely misfires across multiple cylinders.

I think if he goes into the misfire counters he will probably find 3 cylinders on one bank to be affected. If I had to load my parts cannon, it needs a new head.
 

JTK

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@The Critic I was kind of shooting from the hip since they were still daily driving this Jeep and described some fuel economy loss and loss of power (among other things).

I wouldn't think the vehicle would be usable if one whole bank was dropping out even intermittently.

Interesting none the less. I don't follow Jeep forums, but this has got to be the newest Pentastar I've heard of such problems on. Typically it's the 2011-2015.
 
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I wouldn't think the vehicle would be usable if one whole bank was dropping out even intermittently.

A V6 can run pretty well even on 3 cylinders. Had a V6 years ago that all 3 of the sparkplugs in the front bank worked loose. No idea why that happened (I think someone didn't torque them enough), I retorqued them and it was fine. It was pre-OBDII, and never set a code.
 
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I don't think he has a dead cylinder; most likely misfires across multiple cylinders.

I think if he goes into the misfire counters he will probably find 3 cylinders on one bank to be affected. If I had to load my parts cannon, it needs a new head.
I don't stock multiple heads for nothing so I will concur with this statement.

I watched a video by Pine hollow diagnostics on YT yesterday diagnosing a missfire on a grand caravan with the same ERB engine code. Needed a head after doing a clear flood with live data which I believe was pico scope. You could hear the lack of compression as it cranked. If its not ticking anymore than normal valvetrain sounds a head would be my guess.

OP - Looking at your story, it seems you got a hold of a service advisor with a poor attitude. Regardless, if its under power train just let them fix it. Chrysler techs see so many of these ERB 3.6s its pretty easy for them to diag unless there a newbie maybe. I can check warranty status if you want to PM me your vin btw.
 

Gasbuggy

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Like @Danno says, there's tons of youtube videos out there where people fire the parts cannon at their pentastar replacing coils, spark plugs, injectors, etc, when it's a mechanical problem causing a dead cylinder.

Sorry if I missed it, but If you crank the engine over in clear flood mode can you hear the cadence of a dead-ish cylinder?

If you do a scope/scan with an amp clamp knowing the firing order, this will pinpoint the dead cylinder as you're cranking it over. Like said, usually it's a rocker arm problem causing loss of compression in one or more cylinders.

I don't think top end parts are all that expensive or hard to come by for pentastars. A bit of labor of course. If it does need to be torn into and she wants to keep this vehicle, I'd invest in one of those Doorman all aluminum oil cooler/filter housings and swap that out while they're right there.


Ha, parts canon.

Cam lobe(s) would make sense, if it's not totally wiped out and lifting enough to run ok in most driving situations.

The first time I was in this Jeep, before this CEL issue, I asked "does it usually idle like this?" Its rough enough to make you wonder but not enough to say there's a problem. But then I thought "Chrysler Corp" I remembered years ago being in a new Jeep Liberty when the 3.7 came out and thinking that idled rough, turned out to be "normal"

If I cup my hand over the tailpipe there's no detectable miss.
 
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JTK

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I don't stock multiple heads for nothing so I will concur with this statement.

I watched a video by Pine hollow diagnostics on YT yesterday diagnosing a missfire on a grand caravan with the same ERB engine code. Needed a head after doing a clear flood with live data which I believe was pico scope. You could hear the lack of compression as it cranked. If its not ticking anymore than normal valvetrain sounds a head would be my guess.

OP - Looking at your story, it seems you got a hold of a service advisor with a poor attitude. Regardless, if its under power train just let them fix it. Chrysler techs see so many of these ERB 3.6s its pretty easy for them to diag unless there a newbie maybe. I can check warranty status if you want to PM me your vin btw.
Yep I watched that one too. I'd be curious to know if it's a head problem (crack, etc) or a valvetrain problem though.
 

D60

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Ha, parts canon.

Cam lobe(s) would make sense, if it's not totally wiped out and lifting enough to run ok in most driving situations.

The first time I was in this Jeep, before this CEL issue, I asked "does it usually idle like this?" Its rough enough to make you wonder but not enough to say there's a problem. But then I thought "Chrysler Corp" I remembered years ago being in a new Jeep Liberty when the 3.7 came out and thinking that idled rough, turned out to be "normal"

If I cup my hand over the tailpipe there's no detectable miss.
My '19 has always idled rougher than I thought it should, even when new. As I recall every 3.6 I drove was this way. Just funny you mention it 'cause even if it's normal, I concur

I swear on cold starts (remote) you hear a miss in the exhaust ~1 second after starting, then all is normal. But I deleted the muffler so it's easy to tell and maybe simultaneously amplified more than it should be
 

D60

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Like @Danno says, there's tons of youtube videos out there where people fire the parts cannon at their pentastar replacing coils, spark plugs, injectors, etc, when it's a mechanical problem causing a dead cylinder.

Sorry if I missed it, but If you crank the engine over in clear flood mode can you hear the cadence of a dead-ish cylinder?

If you do a scope/scan with an amp clamp knowing the firing order, this will pinpoint the dead cylinder as you're cranking it over. Like said, usually it's a rocker arm problem causing loss of compression in one or more cylinders.

I don't think top end parts are all that expensive or hard to come by for pentastars. A bit of labor of course. If it does need to be torn into and she wants to keep this vehicle, I'd invest in one of those Doorman all aluminum oil cooler/filter housings and swap that out while they're right there.
Supposedly the JL's don't need this/have a different setup. Dorman doesn't list their part to fix the '18+ JL
 
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Supposedly the JL's don't need this/have a different setup. Dorman doesn't list their part to fix the '18+ JL

In the video at the 7:51 mark , he describes the application and different Pentastar generations. Basically the Dorman housing is designed for the GEN 2 but will also fit the early Gen 1 applications if you have a Gen 2 oil cooler to attach. The JL is the latest Pentastar "Upgrade" Gen 3 series and Dorman does catalog it for either Gen 1 or Gen 3 Pentastars because the oil cooler that sits on top is different between all 3 Gens but only designed for the Gen 2 engines.

 

D60

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In the video at the 7:51 mark , he describes the application and different Pentastar generations. Basically the Dorman housing is designed for the GEN 2 but will also fit the early Gen 1 applications if you have a Gen 2 oil cooler to attach. The JL is the latest Pentastar "Upgrade" Gen 3 series and Dorman does catalog it for either Gen 1 or Gen 3 Pentastars because the oil cooler that sits on top is different between all 3 Gens but only designed for the Gen 2 engines.


I'm not being a smartaz and likely I'm just a dumbaz but I'm not following you.

I've watched that vid before and based upon the 7:51 mark it would seem it doesn't fit.

I'm also not understanding
"The JL is the latest Pentastar "Upgrade" Gen 3 series and Dorman does catalog it for either Gen 1 or Gen 3 Pentastars because the oil cooler that sits on top is different between all 3 Gens but only designed for the Gen 2 engines."

I guess really all that matters is: are you saying the Dorman part fits JL's? Y or N?

Screenshot_20220303-141418_Chrome.jpg
 
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I'm not being a smartaz and likely I'm just a dumbaz but I'm not following you.

I've watched that vid before and based upon the 7:51 mark it would seem it doesn't fit.

I'm also not understanding
"The JL is the latest Pentastar "Upgrade" Gen 3 series and Dorman does catalog it for either Gen 1 or Gen 3 Pentastars because the oil cooler that sits on top is different between all 3 Gens but only designed for the Gen 2 engines."

I guess really all that matters is: are you saying the Dorman part fits JL's? Y or N?

View attachment 91220
It has not been proven out the Dorman housing will fit the JL. (Gen 3)

He makes reference to another video where he swapped a Gen 2 OEM Mopar oil filter and cooler housing complete assembly to a early GEN 1. If you install this Dorman housing to a GEN 1, you would need the oil cooler off a removed Gen 2 assembly and install it on the Dorman housing.

I suspect the same is similar to retrofit this housing to a Gen 3 but not 100% certain on that.

Dorman is playing it safe of only supporting the GEN 2 application only.

Below is the video on the Gen 2 to Gen 1 swap for the OEM assembly.

 
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