PCV VALVE ISSUES, PRE DETONATION, CARBON BUILD UP

[IanNubbit]

Ive had to argue with Engineers and managers that the PCV Valve IS a cause of problems on these. They finally released a TSB about 2 months ago about what for techs to look out for

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[SultanWild]

Ive had to argue with Engineers and managers that the PCV Valve IS a cause of problems on these. They finally released a TSB about 2 months ago about what for techs to look out for

Exactly, appreciate your response

 

[azjl#3]

"worked great for me but I sold it already"

The PUG1 motor is a higher compression engine than the previous iteration of the 3.6, but the PCV design is functionally the same and the pentastar engine has NEVER in history consumed an appreciable amount of oil. It's a tuning problem combined with low quality gas and oil.

This^^

 

[OBD]

During the first 1000 miles of breaking in my 2021 3.6 it used a half quart.Not wanting to take chances, I installed a catch can.The unit I installed has a drain valve located inside the driver's wheel well.We just took an 840-mile trip and at about the 600-mile mark I thought I would check the can as we were running as high as 80mph a lot of the day.What came out was all oil, no water, and while not an excessive amount.....it was more than I would have wanted going down the intake.I plan on keeping this Jeep for the duration, so spending cash for the can and the occasional bottle of Sea foam is worth the peace of mind.I have run external venting systems on Harley's for decades and having seen the internals of those engines....with and without....I can say confidently.It makes a difference.I am NOT saying you have to run a can, but I will.

 

[azjl#3]

My dear don't think I'm arguing with you, when this first happened to me I was totally upset with a brand new vehicle doing this. After a research i found out it is not only me. In fact I'm more surprised that this was not an issue with the first gen 3.6 pentastar and never experienced this in a JK. Maybe when pentastar upgrade came out with some compression ratio changes or the way they designed the PCV, I'm not sure. Believe it or not, my dealer had replaced so many engines under warranty for many customers and the issue came back again. By the way my spark plugs where totally fine and clean. So I don't know what is going on, and Stellantis issued a TSB for this and they are aware of this issue. TSB issued for a reason.

So the TSB does note a new improved PCV. But I owned/still own three of those year 3.6, no issues, ever. No one I know, has an issue, probably 12 jeeps in total.

I think us being skeptical is only about the part saying get a catch can, for that, the 3.6 is not the engine that needs a catch can. Good find on the TSB, hope it does solve the problem.

 

[SultanWild]

During the first 1000 miles of breaking in my 2021 3.6 it used a half quart.Not wanting to take chances, I installed a catch can.The unit I installed has a drain valve located inside the driver's wheel well.We just took an 840-mile trip and at about the 600-mile mark I thought I would check the can as we were running as high as 80mph a lot of the day.What came out was all oil, no water, and while not an excessive amount.....it was more than I would have wanted going down the intake.I plan on keeping this Jeep for the duration, so spending cash for the can and the occasional bottle of Sea foam is worth the peace of mind.I have run external venting systems on Harley's for decades and having seen the internals of those engines....with and without....I can say confidently.It makes a difference.I am NOT saying you have to run a can, but I will.

@OBD, Appreciate your valuable response, this is what my friends are doing now with their JLs, oil catch can and can of sea foam spray top engine cleaner every once in a while. They used to have the noise and it's gone now for some and reduced to bare minimum for others, saved them from a big job by removing the cylinder heads.

 

[SultanWild]

So the TSB does note a new improved PCV. But I owned/still own three of those year 3.6, no issues, ever. No one I know, has an issue, probably 12 jeeps in total.

I think us being skeptical is only about the part saying get a catch can, for that, the 3.6 is not the engine that needs a catch can. Good find on the TSB, hope it does solve the problem.

Exactly sir, not everyone experiencing the same issue, but at least TSB was issued for whomever experiencing this.

 

[krupa33]

i had pinging/knock on 87 octane, so now i just run 93. and yeah a catch can does help especially if you dont have access to higher octane. the oil particles coming into the intake are gonna dilute the fuck out of the A/F ratio. its a high comp motor it loves higher octane regardless.

 

[Willys41]

My UPR catch can stopped ALL Pre Detonation completely
At one point it was so bad I hated to drive it
I installed it at about 10,000 miles and glad I did
I now have 22,000 miles and have not heard ANY Detonation after the catch can
I also added a 4ft 1/2 drain hose with a ball valve at the end of the hose
There is never any oil in the can its all in the hose so there is no chance of it getting sucked in to the intake. I drain every 1000 miles
Two days ago I replaced the PCV valve with the updated version and will see if it makes any difference

 

[mwilk012]

Nobody seems to want to talk about the fact that the PUG1 has a real shitty EGR system on it, dumping carbon back to the intake no matter what you think you are doing with your tablespoon of oil from the PCV.

 

[m3reno]

Nobody seems to want to talk about the fact that the PUG1 has a real shitty EGR system on it, dumping carbon back to the intake no matter what you think you are doing with your tablespoon of oil from the PCV.

What do you suggest is the fix for this problem? I had light pinging at low rpm's and by going to 89 octane it seemed to fix the issue. I only use Shell gas which is a top tier gas.

 

[Willys41]

mwilk012
I have known this years

EGR works by routing, cooling and feeding a controlled amount of exhaust gas created during combustion back into an engine's intake air system. This process dilutes the air and fuel mixture that enters the combustion chambers, which reduces the engine's peak combustion temperature.
ALSO
An EGR valve that's stuck closed can lead to abnormally high combustion temperatures, resulting in spark knock (also known as detonation). If left unchecked, that spark knock can cause costly engine damage.

The problem with the PCV is it dilutes the air fuel mixture with oil and reduces octane

 

[Willys41]

m3reno
Install a good quality oil catch can will probably eliminate your detonation
It did with me. I have not heard any detonation after installing my catch can .

 

[mwilk012]

The problem with the PCV is it dilutes the air fuel mixture with oil and reduces octane

I assume you would have to be consuming a large amount of oil for this to be the case. We are seeing consumption rates at most of 1/4 quart in 1000+ miles. thats ~60 gallons of gas. I’m not sure exactly how the octane rating would be calculated, but I don’t see a dilution of 240:1 causing a problem.

 

[Willys41]

Pre catch can detonation at low RPMs
After catch can ZERO detonation
Your results may very

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