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Spark knock?

Logan-Kn

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Hey all, I’ve got 30k on my 3.6 rubi, and I’ve noticed sometimes between 2nd and 3rd gear around 2k to 3k rpm, I’m getting what some are referring to as “spark knock”. No loss in power, just sound a little like a diesel for a couple turns. I’m running shell 91 and it seems to help and but. Has anyone figured out a solution for this? As it seems FCA acts like it doesn’t exist.
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DaltonGang

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Add some good ethanol treatment. Sometimes water gets inside the system, especially with ethanol gas. It doesnt take much water to cause intermittent issues. Mine did this, and the 91-93 octane helped, but was very expensive for every tank. 87-89 octane now. I add some ethanol treatment every once and a while. The engine purrs like a kitten, without any intermittent knocks now.
 
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Logan-Kn

Logan-Kn

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Add some good ethanol treatment. Sometimes water gets inside the system, especially with ethanol gas. It doesnt take much water to cause intermittent issues. Mine did this, and the 91-93 octane helped, but was very expensive for every tank. 87-89 octane now. I add some ethanol treatment every once and a while. The engine purrs like a kitten, without any intermittent knocks now.
Good to know, I think the last shell I filled up at didn’t have very good gas. What fuel treatment do you recommend?
 

DaltonGang

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Good to know, I think the last shell I filled up at didn’t have very good gas. What fuel treatment do you recommend?
It varies. I've used STP, and I like the Techron stuff. I've used others too. I'm not real picky with the fuel treatment, as long as it is a respected brand, and not expensive.
 

chadk77

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I just started noticing the same thing happening with my Rubicon. 15k miles and it usually happens under load or low RPMs. I've seen some say that a catch can will help with this issue along with higher octane fuel and/or fuel treatment. I'm going to try the gas treatment/ high octane fuel and see if it helps.
 

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Lucky #7

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I am having the same issue. 2021 JLUR with 3.6, manual transmission, 14,600 miles. Happens under load or low rpms. I pump 87 octane. I am also going to try gas treatment today. I have the doors off so I can hear every knock, every chunk of gravel in the tires, every yell of joy that I have the doors off... ;)
 

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I’ve had a lot of knock with my 6speed manual when I run anything less than 91oct. The v-6 don’t like crap gas.
 

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Refer to TSB 09-012-22 for a solution to the spark knock issue. If you are already knocking then a top end tear down is required to remove the carbon buildup. The solution is to replace the original PCV valve with a new design as listed in the TSB. The cause is too much oil getting through the original PCV valve and dripping oil into the intake systen. Some have installed “catch cans” to catch the excessive oil so it can be disposed of before entering the intake. That’s just a bandaid solution.
If you are out of warranty there may still be hope. Since the PCV valve is an emissions component, and it’s fairly clear that a bad design of the PCV valve is causing the oil in the intake, they may consider it under the emissions warranty. The TSB covers 2018 thru 2022 JL, 2020 thru 2022 JT and 2018 thru 2022 WK with the 3.6l with or without eTorque. Hope this helps. Mine was into four dealers for various minor issues before this last one discovered the TSB. Dealers are reluctant to search for TSBs related to your vehicle.😖
 

krupa33

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two options:

run 91+
get a catch can (UPR makes a nice one for the 3.6) and run 89. it will still knock at low RPM's on 87 with a catch can. especially if you have M/T.

https://www.tsbsearch.com/Jeep/09-012-22

even updating the PCV, itll still happen on 87. the system is a dogshit design. the fine oil mist coming into your intake is fucking up your A/F ratio. the fact this high comp motor somehow was passed to run a minimum of 87 is beyond my comprehension. there is a class action lawsuit for this. as well as the lifter/rocker arm failures.
 

dstrahm

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two options:

run 91+
get a catch can (UPR makes a nice one for the 3.6) and run 89. it will still knock at low RPM's on 87 with a catch can. especially if you have M/T.

https://www.tsbsearch.com/Jeep/09-012-22

even updating the PCV, itll still happen on 87. the system is a dogshit design. the fine oil mist coming into your intake is fucking up your A/F ratio. the fact this high comp motor somehow was passed to run a minimum of 87 is beyond my comprehension. there is a class action lawsuit for this. as well as the lifter/rocker arm failures.
Did you have the work done as described in the TSB?
 

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alphawolff

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The compression was raised with the JL from the old 3.6L. I can't fathom why they didn't raise the octane requirements, or at least suggest it like a lot of vehicles do. The new 3.6L really requires 89 rather than 87 for best performance. It was blatantly noticeable in the 2020 gladiator I had.

Can't go wrong running 91/93 either.
 

dstrahm

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This is some of what the dealer found when they recently performed the TSB repair. Carbon deposits can cause pinging/Preignition even with higher octane fuel. The replacement PCV valve was in a box with the new p/n but the actual valve had one of the previously mentioned p/n molded into the casing. I’m assuming the new p/n indicates a smaller opening. Haven’t tested in a trail setting yet but haven’t been able to make it ping either.
Jeep Wrangler JL Spark knock? IMG_0575

Jeep Wrangler JL Spark knock? IMG_0573

Jeep Wrangler JL Spark knock? 20231117_124722
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