2021 3.6 MT Detonation

[Gvsukids]

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.

Is this true for boat motors too?

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[bleda2002]

Is this true for boat motors too?

Depends on the age of the boat and how often you use it.

The main issue I know of is that ethanol can eat certain kinds of rubber/seals. Modern automobile engines are designed with this I'm mind so the seals are made out of material not affected by ethanol. Mot small engines and many boat engines aren't designed for this so running ethanol over a long period of time can damage them.

Some of the no swapping also came from back when ethanol was first being added. Ethanol is really good at cleaning out deposits that normal gas wouldn't touch. This would cause clogged fuel filters and such and gave ethanol a bad rap. I know when I brought my car from Florida to Minnesota it had been on a steady no ethanol diet, ended up needing to replace the fuel filter twice in fairly short order as the ethanol "cleaned" the old deposits

 

[onewhippedpuppy]

Watch the video on this thread, are you sure it’s detonation?

https://www.jeepgladiatorforum.com/...-when-accelerating-manual-transmission.57585/

 

[ShadowsPapa]

Is this true for boat motors too?

Most boat motors I've owned or worked on stated "no ethanol".
There's no reason to "run a tank of high test now and then". It literally does nothing that a GOOD quality top tier gas doesn't do. Good gas has the detergents and additives at any octane level.
Octane is simply the ability to resist self-ignition. It offers nothing else unless a specific company says they add something to their higher octane to get you to buy it.

Reasons you may wish to run pure gas in a boat - two cycle engines rely on the fuel to lubricate it, and, boats often sit for a while with fuel in the system.

The main issue I know of is that ethanol can eat certain kinds of rubber/seals. Modern automobile engines are designed with this I'm mind so the seals are made out of material not affected by ethanol. Mot small engines and many boat engines aren't designed for this so running ethanol over a long period of time can damage them.

Some of the no swapping also came from back when ethanol was first being added. Ethanol is really good at cleaning out deposits that normal gas wouldn't touch. This would cause clogged fuel filters and such and gave ethanol a bad rap. I know when I brought my car from Florida to Minnesota it had been on a steady no ethanol diet, ended up needing to replace the fuel filter twice in fairly short order as the ethanol "cleaned" the old deposits

I was a mechanic in a shop near where I35 and I80 cross and mingle. We had towing service, this was at the time ethanol first came to Iowa in the late 70s.
The biggest problems were as you said - cars would stumble and hesitate because the rubber cups on the accelerator pumps would swell and stick so the accelerator pump didn't work. Massive lean moment when taking off. Float valve seats were often a rubber compound so carburetors would flood as the float couldn't shut off flow, and it ate some of the Motorcraft 2100 and 4300 floats.
Tomco was among the first to offer kits with viton float valve tips or seats, and ethanol-proof accelerator pump cups. We went through a whole lot of Tomco carburetor kits.
Fuel hoses and carb kits - no more troubles.............. well, sort of.............

I also learned how to quickly drain fuel tanks and plug and solder the hole I made to drain them.
As you said - people who had crappy fuel in their tanks that left crud, or who had water in the tanks, or where a station dumped the new ethanol blend into existing tanks, boy, did it clean out that stations tanks - right into YOUR gas tank.
So we had a lot of vehicle towed in with totally plugged fuel filters and those clowns at GM who had the better idea of a fuel filter BYPASS for when the filter got plugged (idiots! If the filter was plugged due to crap - the pressure pushed the filter open and let unfiltered fuel into the carburetor costing owners of GM vehicles a lot more because now the carburetor was full of that stuff. What sort of a dope bypasses a filter? GM., that's who. Ford and AMC let your vehicle stop running - they blocked the crud.
Anyway, we kept a barrel handy and I got good at draining fuel tanks, cleaning them out, soldering the hole closed, and I was a pro at carburetors after a few weeks.
Then things settled down and after a year of that, no more problems. Most had things cleaned out, the stations got cleaned up, and many carburetors were rebuilt with the better parts and new fuel hoses.

Anyway, back on the topic of swapping back and forth on fuel - there's no reason to. It doesn't help anything. For modern vehicles, it just adds to the time the PCM readjusts for the different fuels. Doesn't hurt, but since it doesn't help - why do it?
There's no advantage. Pick a good fuel and run it.

 

[Artsifrtsi]

I get a light amount of chatter, but have found that alternating tanks of 87 and 89 keeps it quiet.

 

[onewhippedpuppy]

For those of your who have fixed your noise with running higher octane gas, could you check out the video in the link that I posted to see if it’s the same sound?

 

[ShadowsPapa]

If anyone says "my engine is quieter with xx octane" then the fuel they are using has octane drift. These will run fine on 87 but not all 87 is the same. It gets into some rather complex chemistry and explanation, but there's a great chance going to a different source for the fuel it would be fine on the other 87. (or it's a perception as there's some common beliefs out there that don't always hold water)

Going back and forth doesn't do anything other than mix the batches - unless you drain the tank until it's dry, you are mixing things up. The long term fuel trim doesn't change in seconds.
There's only 2 points difference between 87 and 89, hard to imagine that making a big difference, especially when put into a tank that isn't totally empty. The 89 is reduced by what's in the tank.
It also should be noted that ethanol blend fuels aren't exact octanes. There is no way to measure ethanol's octane. So it's an assumed number based on research. The engine that is used to check gasoline octane is a carbureted engine, jetted for gasoline. So the octane of ethanol is a research number, not a test number.
IF you look in google for "what is the octane of ethanol" you'll find some variation. So when they make 10% blend 87 octane fuel, they are stating with a known and adding ethanol and figuring out what the octane "must be", making it more complex.
E85 is 51 to 85% ethanol, so you may be getting half gas in your flex fuel vehicle.
U88, or E15, is 10.5 to 15% so what you get may vary

 

[Akgladiator]

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.

Being cheap does not pay..
High compression engine with regular gas is asking for trouble

 

[ShadowsPapa]

Being cheap does not pay..
High compression engine with regular gas is asking for trouble

People need to stop looking at the static calculated compression ratio.

These are FINE with 87 and hundreds of thousands of them on the road with no ping, no issues, is proof.
Further, a little detonation, if these are actually even doing that, isn't killer.
These have VVT and VVL not to mention sensors to detect knock and change timing and other parameters. The VVT and VVL can be used to relieve compression pressure.
These are not your old-school 390 - which by the way even with slow burn chambers, didn't do too bad on ordinary gas. You can take a high compression engine like that and relieve the pressure just with the cam choice - and yet people ignore the fact that these have a 70 degree intake timing swing and dual valve lift. Changing valve lift and the timing of opening and closing can greatly reduce the compression pressure. 11.3 is a ratio based on volume and 100% pumping efficiency with valves opened and closed at exactly BDC and TDC. These don't operate that way.

There are very very few of these which may even have any true ping at all. Most have been proven to be other sounds.
Chamber design, intake manifold runner design and other factors can help negate any detonation issues.
People are thinking old engine design and the 1960s.
Engines have changed.

LSPI can be a killer - but no one seems to pay attention to that, all they think of is detonation and oh my god, my engine is going to blow! It pinged!
We've had 5 of these 3.6s with no ping issues at all, and the numbers out there support "ping" being an extremely uncommon thing with these.
I'd also question - if it truly pings - is it detonation or LSPI?
And yet people don't even consider their oil choice could be making LSPI happen - it's all about "if it's making a noise it's detonation and it's going to blow.
No, not true.

This is from a GM engineer - and I 100% agree as I've driven performance cars for decades, and have built the engines for same ->

BTW - there are modern engines running HIGHER "ratios" on ordinary pump gas - like 87 octane.
Mazda, for example - 14:1
It's how they control the valving, scavenging and so on. It's about turbulence, chamber temperatures and pressures which can be manipulated with valve timing and lift.
Some Toyota engines run 14:1
There are others.
People need to stop looking at that stupid 13:1 number as if it's a big deal. Today, it's really not.
Engines have changed.

 

[onewhippedpuppy]

That was part of my request to watch the video on the other thread. There are a number of people getting a strange part throttle resonance on manual transmission equipped JTs. Lots of sounds get called detonation when they are really not. As was just explained very well, detonation on modern engines is quite rare.

 

[reverse01134]

I have the same issue on my 3.6 AT. It was really bad last year summer. I think temperature is a major factor as I did not hear the noise below 40' at all. Some of you mentioned costco gas. I went costco a lot last year, not so much in this year. I only go to major brands - Mobil, BP, Shell, Sunoco, Exxon. It hasn't been that bad this summer but I still hear the noise occasionally.

I am debating whether I should take the truck to dealership because I haven't so far found any threads regarding this issue that anyone found a permanent fix. I have feeling it will be just waste of time arguing with dealership.

 

[ShadowsPapa]

It hasn't been that bad this summer but I still hear the noise occasionally.

Why can't people accept that it's not a killer, especially "occasionally".
The dealer is going to refer you to the book and say "ignore it, it's normal"
99% don't give any ping, but the few that may - and I say may as it's not been decided that ALL are true detonation, it's not something to lose sleep over.

I guess, I post this again from a GM engineer who is responsible for the Northstar engine -

Absolutely temperature IS a factor! Cool engines do not detonate. Only hot engines (fully warmed up, and I don't mean "coolant temperature" I mean the entire engine) warmed or above normal.
If it's not reach normal operating temperature and been there for a while, it's not detonation.

......... has anyone given any thought to other factors? Crap oil that's not up to modern specs can cause a ping.

 

[ShadowsPapa]

There seems to be an obsession with ping - as if no one has heard an engine do it before.
And yet no one has shown a 3.6 Pentastar with detonation damage.

 

[Artsifrtsi]

There seems to be an obsession with ping - as if no one has heard an engine do it before.
And yet no one has shown a 3.6 Pentastar with detonation damage.

Not saying mine is det, but if I use only 87, and not something between that and the 89 at out pumps here on base (or anywhere... have tried multiples across the US) the engine rattles at startup; no notice of the rattle after warmed up. Using the 89, startup is quiet, and smooth.

 

[reverse01134]

Why can't people accept that it's not a killer, especially "occasionally".
The dealer is going to refer you to the book and say "ignore it, it's normal"
99% don't give any ping, but the few that may - and I say may as it's not been decided that ALL are true detonation, it's not something to lose sleep over.

I feel a lot better If this is normal and nothing to worry about. I am curious if engine break-in does anything to do with this because it was pretty bad last year. After 15k miles on odometer, It's not that bad this summer and I am getting better MPG!

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