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Wrangler Rubicon JLU 3.6 engine pre-detonation

Jimmy_jak

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Just dropped mine off at the dealer. Getting oil changed via new buyer thing and told them to look at the sound again. I told them about it once before and they said try different fuel. Didnt do anything. Ill let yall know.
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JeepCares

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Just dropped mine off at the dealer. Getting oil changed via new buyer thing and told them to look at the sound again. I told them about it once before and they said try different fuel. Didnt do anything. Ill let yall know.
Hi Jimmy_jak,
We would love to know how your dealer diagnosed this. If you need further assistance, please send our team a PM with your VIN.

Kathryn
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Jimmy_jak

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Hi Jimmy_jak,
We would love to know how your dealer diagnosed this. If you need further assistance, please send our team a PM with your VIN.

Kathryn
JeepCares
They didn't

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jayteal

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I'll add my .02 here...I had this same thing and switching to 89 octane completely fixed it. Gasoline brand doesn't seem to matter, at least in my case.

Also, not to be pedantic but I've seen a few folks use the term "pre detonation". This isn't a thing. There is pre-ignition, and there is detonation, and they are completely different from one another.

Same here, I use 89 now and it's made a world of difference for just $4 extra dollars at fill up.
 

JeepCares

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They didn't

20200217_161827.jpg
Thanks for the follow up, Jimmy_jak.
I understand why it may be frustrating to not be able to diagnose a concern. Unfortunately our team is unable to diagnose your vehicle ourselves, therefore we rely on our dealers for this information. If you would like to get a second opinion from another dealership, our team would be happy to assist you during your servicing visit.

Kathryn
JeepCares
 

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AMKRubicon610

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Iā€™ve noticed this with mine too, manual trans in 3rd gear. Glad Iā€™m not the only one. Anyone have premature engine failure from this? Is that a concern? I havenā€™t tried anything other than 87, I have about 800 miles on my Jeep
 

Johnbuz

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My mitigations are to stick to 93 octane, and keep the rpm's above 2000 at all times. The pinging seems to happen when the air temp is warm, the engine is warmed up, and the engine is under load below 2k rpm. The pentastar is no low end truck monster but a high reving car engine.
 

joe@upr

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The easiest fix for any detonation is to get a good synthetic oil that is not combustible to eliminate the risk of hurting rings or piston skirts. The low-speed pre-ignition is the number one cause we see on Jeep's having engine trouble over time. This will make the noise go away and a bit safer operation.

Just remember that you are only correcting the knock or pre-ignition and you are not addressing all the oil no matter how good it is or what brand is still robbing power every time you drive the vehicle as it's getting into the combustion chamber and diluting the octane.

If you install a properly performing catch can and run at least 89 octane minimum you will see on average 1 to 1.5 MPG increase in mpg and the low-end throttle will be clean and crisp giving you the best of both worlds and piece of mind.

Just a bit of info to add.

Have a great day, Joe@UPR
 

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intentsrig

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So I have not run 87 in awhile but I ran two tanks through and it was pinging all the time. So much so that it was annoying and with my half doors on itā€™s a lot louder/ more noticeable.

Ran the tank low and refilled with 91. Drastically improved. No doubt that the higher octane helps. Even lugging the engine does not cause pinging.
 

MrSir

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Sure hope you have better luck with your STAR case than I did mine!! The FCA local engineer deemed it to be 'normal'. The tech and service manager are at a loss, as there is no software updates to program. All admitted to it having pre-detonation, where it is easily reproducible.
FCA Cares won't do anything anymore.. Comment is 'bring it in when it gets worse.' (guess that is when the parts appear below the Jeep?)

Tough to keep positive attitude to all my friends that are purchasing or interested in new JL or JT Jeep...

#ManualTransmissionsMatter
#FCAEngineEngineering https://www.onallcylinders.com/2015...mination-9-ways-to-prevent-engine-detonation/
Here in Ontario Canada, the Dealership told me the exact same thingā€¦.drive it until it gets worseā€¦.FCA technicians
2018 JL 2020 JL both with the identical pattern of rattle when warmed up (like rocks in a can 1-3 seconds) around 1700-2300 rpmā€™s.
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