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2021 3.6 MT Detonation

Nuclear_Inc

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Hi,

I have a 2021 Gladiator overland MT 3.6 with engine detonation. I've owned it for a year without issues. Previous fill up at Costco with 87 caused real bad detonation. Every time I would accelerate low speed 3 or 4th gear it would sound nasty LOUD and was able to replicate it every time I tried. I went and dumped a bottle of Lucas octane booster, Lucas injector cleaner and topped off tank with 6 gallons of 93 octane. It went away slowly after riding for a bit to clear the lines of bad fuel. Fast forward I went ahead and filled up today full tank with 87 BP station. Occasionally s heard a very quick and short detonation. Had to lower music and a/c to hear it carefully.

Now I know 87 is the recommended fuel per the owners manual. However, after owning this Jeep for over a year on a steady diet of 87 octane. Why would it start doing this? Does it take a few tanks for the ECM to adjust timing back to 87 after running the boosted octane gas? All though its nearly its very hard to replicate or hear with the fresh 87 fill up. Definably something's either wrong with the timing. Or my area just happens to have poor fuel lately. Jeep has 13k miles with 1k miles on the current engine oil (Amsoil Signature Series 0w-20/ filter).

I drive roughly 70% highway 20 miles a day in the Twin Cities It's been almost a year of trouble free engine with 87 fuel.
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The general consensus is that the 3.6L hates doing work at low RPM's. It is much happier high in the rev range. If you're starting these low speed acceleration runs at like 1400 rpm, it won't be happy.
 
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Nuclear_Inc

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The general consensus is that the 3.6L hates doing work at low RPM's. It is much happier high in the rev range. If you're starting these low speed acceleration runs at like 1400 rpm, it won't be happy.
The general consensus is that the 3.6L hates doing work at low RPM's. It is much happier high in the rev range. If you're starting these low speed acceleration runs at like 1400 rpm, it won't be happy.
I understand that however I have been driving same driving conditions over a year with zero issues. Why now?
 

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I understand that however I have been driving same driving conditions over a year with zero issues. Why now?
I'm guessing you just got a batch of bad gas. Costco gas is supposed to be top tier, but mistakes happen. I've been running mostly Sam's Club gas for three years with no problems. I also use Costco with no issues.
 

SteveInOrlando

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The other option might relate to the variable valves and the lifters. If you get into it hard do you have valve clatter?

Just a thought as a lot of people with the flattened cam lobes have complained of detonation.
 

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Nuclear_Inc

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I'm guessing you just got a batch of bad gas. Costco gas is supposed to be top tier, but mistakes happen. I've been running mostly Sam's Club gas for three years with no problems. I also use Costco with no issues.
I'm guessing it's trying to adjust to 87 after running the boosted crap fuel.
The other option might relate to the variable valves and the lifters. If you get into it hard do you have valve clatter?

Just a thought as a lot of people with the flattened cam lobes have complained of detonation.
My engine idles and revs nice and quiet no valve chatter. The new fuel fill barely detonated 1-2 times on a 20 min trip. Its very hard to replicates and when it does it's for a split second. Been running Amsoil Signature since 2k miles. No obvious metal in the filter media and just had a great engine oil analysis report at 7k miles. I believe if the cam lobes were bad it would chatter at all speeds with or without load.
 

ShadowsPapa

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. Occasionally s heard a very quick and short detonation. Had to lower music and a/c to hear it carefully.
IF that's all it is, don't sweat or lose sleep over it.

The general consensus is that the 3.6L hates doing work at low RPM's. It is much happier high in the rev range. If you're starting these low speed acceleration runs at like 1400 rpm, it won't be happy.
And yes, people seem to want to shift like they are going to blow the engine if they hold it over 3,000-3,500 rpm.
When I accelerate like my wife isn't with me, it's nothing for my automatic to hold to over 3500 before shifting. Redline isn't until 6500.
I hold my 4.0 for over 3,000 rpm,. sometimes over 3500 and it redlines in the 4,000 range.

Then there's the fact that 87 isn't 87 isn't 87. It gets into really serious complex chemistry, but some 87 is better at different temps and RPMs than other 87.

Anyway, ignore minor really quick ping - if it's detonation and it's that quick and short and you can't hear it easily, it's not going to blow the engine. Consider keeping RPMs up when shifting.

And finally, there's LSPI which oil can cause. That's why there's a new oil standard that tests for LSPI.
LSPI is dangerous and when it causes detonation as well, the combination is bad.
I know people hate the certification stuff and seem to have really incorrect ideas about what it is, and why companies don't comply, but they are mostly wrong.
Again, it's a chemistry thing. But people let their deeply rooted prejudices show when it comes to oil and accepting there might be something to all that testing.

Interesting that in the other threads on this exact topic - one was busy as of the last couple of days - they are manual transmissions. Where's Nacho in this one?
 

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Always had issues with Sheetz gas, my modestly built H/D needs to drink the high octane stuff, just like me!!! It would skip, spit, sputter, backfire, till I'd put name brand fuel and issues would go away. We have a Union 76 in town and they have racing fuel, up to 108. Anyway, every so often a dose of 100 octane goes in the tank. Probably wouldn't hurt for y'all gassers out there to burn some of the better stuff every so often, at least some non-ethanol once or twice a month. Maybe an additive, even us oil burners have fuel issues.
 

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I started using the Sea Foam Fuel Injector cleaner in March. I was adding it once a month, while it was available from Amazon for about $4.50 per bottle. The dealer showed it as recommended for the 30k mile maintenance, but wanted like $100 for a fuel injector cleaner treatment. I've put in five bottles, so far, don't know if it has helped any, doesn't seem to have hurt anything.

https://smile.amazon.com/gp/product/B086RLXJV6/ref=ox_sc_saved_title_3?smid=&psc=1
 

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Interesting that in the other threads on this exact topic - one was busy as of the last couple of days - they are manual transmissions. Where's Nacho in this one?
Mine doesn't ping, so nothing really to add, other than that there's a TSB for low speed and @ idle knock though. I usually run 88 octane e15. If I can't get e15, I run regular 87. I run the e15 88 octane because it's cheaper though, not for the octane.

Edit: The TSB they did on mine was 18-042-22A. @Nuclear_Inc , have you had that one done? I went in for another issue, and they did that TSB on mine.
 

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ShadowsPapa

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Anyway, every so often a dose of 100 octane goes in the tank. Probably wouldn't hurt for y'all gassers out there to burn some of the better stuff every so often, at least some non-ethanol once or twice a month.
Better stuff? No impact on anything wasting money on higher octane every once in a while. It's not better, it's only more resistant to self-ignition.
If you buy top tier 87 from a good station, the higher octane is a waste.
There is no advantage. The thought of filling with "high test" (old school for higher octane) goes back years when the companies used to push the more expensive stuff by talking about all of the extra detergents and so on. Today, buying a TT fuel is all you need to do.
Octane has no cleaning abilities.
Running non-ethanol once in a while also does nothing. There's nothing in straight gas that's not in the blends.
Long ago when the U88 and E85 fuels came out and the systems go to where they are, we were warned don't keep switching fuels - it's a set-back. It takes time for these to adjust to peak efficiency.
 
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Nuclear_Inc

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Mine doesn't ping, so nothing really to add, other than that there's a TSB for low speed and @ idle knock though. I usually run 88 octane e15. If I can't get e15, I run regular 87. I run the e15 88 octane because it's cheaper though, not for the octane.

Edit: The TSB they did on mine was 18-042-22A. @Nuclear_Inc , have you had that one done? I went in for another issue, and they did that TSB on mine.
I have not had any TSM. How long did it take to perform?
 

ShadowsPapa

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I have not had any TSM. How long did it take to perform?
TSB = Technical Service Bulletin
It's a communication between Jeep and the dealership telling them "if customer has this problem, here's what to do".
You won't receive it.
If you go complain about an issue, and the dealership shop looks for resolutions, they may find the TSB from JEEP, apply the suggested fix.
Or, you can find a copy and take it to them.
Sometimes there are "rapid transmittals" that Jeep tells the dealer to perform on certain VINs.
 
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Nuclear_Inc

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Better stuff? No impact on anything wasting money on higher octane every once in a while. It's not better, it's only more resistant to self-ignition.
If you buy top tier 87 from a good station, the higher octane is a waste.
There is no advantage. The thought of filling with "high test" (old school for higher octane) goes back years when the companies used to push the more expensive stuff by talking about all of the extra detergents and so on. Today, buying a TT fuel is all you need to do.
Octane has no cleaning abilities.
Running non-ethanol once in a while also does nothing. There's nothing in straight gas that's not in the blends.
Long ago when the U88 and E85 fuels came out and the systems go to where they are, we were warned don't keep switching fuels - it's a set-back. It takes time for these to adjust to peak efficiency.
I usually always use Costco gas which is considered top tier. Since I had a bad batch of fuel and dumped a can of octane booster. Could it be my engine is now going from real high octane to 87 octane timing with this new fresh 87 tank from BP? Does it take time to relearn and self adjust/ retard the timing? I'm calling me dealer tomorrow to inquire about the TSB. Like I've said several times. Why would I have issues now after running 87 for a year ZERO issues? That bad batch of has had to screw up my engines timing programming.
 

ShadowsPapa

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It hasn't 'messed things up'.
The timing will be "retarded" or advanced as necessary based on the sensors picking up the vibrations in the block, the load on the engine, engine RPM and so on.

The long term fuel trim is more impacted by longer term conditions.
IF you have an injector leaking or dripping in fuel that shouldn't be getting in, it impacts the long term adjustment. Prolonged conditions impact the long term trim.

Short term conditions impact the short term fuel trim - like climbing a hill, changing from in-town to highway, slowing to take an exit and so on.

Detonation isn't always about advanced timing........... lean mixtures, hot spots (or engine running hot), valve operation, and other factors can impact it.

But seriously, I don't take minor detonation - IF that's truly what this is - it might not be - as a total disaster.
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