Proof that 87 Octane fuel is limiting your 3.6

[FLY-DOG]

Brad, If I'm driving and floor the gas to pass someone, it downshifts and revs out pretty high before upshifting; once I back off the gas the RPM hangs and comes down slowly. If driving normally (gently) the RPMs follow along linear to whatever gear it is in normal driving. It's driven this way since new. I've been told this is normal with the factory ECM tune, Can you shed any light on your experience with this phenomenon? It has the 3.6 engine 4,000 miles and has used 93 octane since new.

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[bmpcamry09]

Brad, If I'm driving and floor the gas to pass someone, it downshifts and revs out pretty high before upshifting; once I back off the gas the RPM hangs and comes down slowly. If driving normally (gently) the RPMs follow along linear to whatever gear it is in normal driving. It's driven this way since new. I've been told this is normal with the factory ECM tune, Can you shed any light on your experience with this phenomenon? It has the 3.6 engine 4,000 miles and has used 93 octane since new.

That is normal behavior on these with the stock transmission tune. The calibration has what is called an aggression counter. It estimates how aggressive your driving is based on how far the pedal is pressed and how long it was pressed down for. Typically the counter starts at 0 and works its way to around 500 or so depending on your OS. 0 to 100 is usually normal driving. 100-300 is moderately aggressive, 400 and up is usually pedal to the metal for 5-10 seconds or longer. Once you let off the pedal, that counter works it's way back down to 0 and will hold onto an "aggressive" shift schedule until it works its way down. If you are in a hilly area or the vehicle is under substantial load, it will take longer for this counter to work it's way back down. This can all be customized within the tune to suit your needs. Stock tires/gear builds usually don't need this tweaked too much, but heavy tire builds IE 40 inch tires sometimes need this area tuned on because with the extra rolling resistance the engine is under load more.

Hope this helps.

 

[FLY-DOG]

That is normal behavior on these with the stock transmission tune. The calibration has what is called an aggression counter. It estimates how aggressive your driving is based on how far the pedal is pressed and how long it was pressed down for. Typically the counter starts at 0 and works its way to around 500 or so depending on your OS. 0 to 100 is usually normal driving. 100-300 is moderately aggressive, 400 and up is usually pedal to the metal for 5-10 seconds or longer. Once you let off the pedal, that counter works it's way back down to 0 and will hold onto an "aggressive" shift schedule until it works its way down. If you are in a hilly area or the vehicle is under substantial load, it will take longer for this counter to work it's way back down. This can all be customized within the tune to suit your needs. Stock tires/gear builds usually don't need this tweaked too much, but heavy tire builds IE 40 inch tires sometimes need this area tuned on because with the extra rolling resistance the engine is under load more.

Hope this helps.

Brad, Thank you for the explanation. I rarely accelerate hard enough to cause this condition and am glad to hear it is normal for the OEM transmission tune and not a faulty condition. I think as long as I am within the factory warranty period I'm reluctant about doing any mods that might impact any issue covered by the factory warranty.

 

[Mr Miami]

Sorry for not reading through all the technical specs and other things that are beyond my pay grade, but what is Stellantis (or any other manufacturer) gaining by what may be considered de-tuning by us common folk. Wouldn't Stellantis tune its engines to safely get the most out of them since they are competing with others that use the performance information for sales and marketing. Even if Stellantis only got 10 or 15 horsepower additional from the engine, that is a big plus when comparisons are done by buyers and "experts" who look at and drive and test these vehicles.

Am I missing something?

 

[bmpcamry09]

Brad, Thank you for the explanation. I rarely accelerate hard enough to cause this condition and am glad to hear it is normal for the OEM transmission tune and not a faulty condition. I think as long as I am within the factory warranty period I'm reluctant about doing any mods that might impact any issue covered by the factory warranty.

I get it!

I don’t know if I mentioned it on this forum or not, but I used to be both a Mopar tech and also a service manager at two different Jeep dealerships. One of which is one of the largest around. To this day I still wrench and I have a factory Mopar WiTech scan tool here at home too.

There are no indicators within WiTech or dealer level scan tools that indicate any tuning or flashing being done. From a warranty standpoint, tuning is not even a consideration on vehicles like these. For example, if you take your Jeep to the dealer for a misfire and they find you have a faulty intake cam (super common), tuning will not even be a consideration. The tech writes it up, the advisor approves it, and the manager or warranty manager will click a couple of buttons and the dealer gets paid for warranty work. Super easy. They won’t know about it either. But for this exact reason, I tune within the given established parameters set by Stellantis deep within the binary of the operating system.

Long story short, tuning does not void a warranty. If tuning would have been discovered, they have to be able to prove that something within the tune caused the issue.

I have tuned more brand new Jeeps than used ones. Just this week I’ve done two 2026 models with less than 1000 miles on them actually.

The great thing about HP Tuners is the tune is built on your existing operating system. It is not its own custom operating system. Your OS number remains the same and everything looks the same on a diagnostic and scan tool front.

Hope this explanation helps. I’m not trying to be a salesman, but fortunately I have the experience and background from the dealer level to be able to understand how it works.

 

[bmpcamry09]

Sorry for not reading through all the technical specs and other things that are beyond my pay grade, but what is Stellantis (or any other manufacturer) gaining by what may be considered de-tuning by us common folk. Wouldn't Stellantis tune its engines to safely get the most out of them since they are competing with others that use the performance information for sales and marketing. Even if Stellantis only got 10 or 15 horsepower additional from the engine, that is a big plus when comparisons are done by buyers and "experts" who look at and drive and test these vehicles.

Am I missing something?

Stellantis puts out a product that satisfies 85 percent of drivers. It’s the other 15 percent like me who realize faults or things that could have been done better. It’s no different than putting bigger wheels and tires on a Jeep. Do you need it? Why didn’t Jeep just do it from the get go? Same philosophy. Just a different side of automotive customization.

If you ever get to experience driving a vehicle stock and then driving the same vehicle that has been professionally custom tuned, you’ll see what I mean

 

[Stan H]

I haven’t been inside of the diesels, but in the gassers, torque demand ramps up gradually in the driver demand/pedal tables as vehicle rolling resistance and speed increases. Basically as your vehicle speeds increases, it takes less pedal to make the same amount of torque demand. That is likely what you’re experiencing. This is also why people are often okay with how throttle tip in feels on the highway but they hate how it feels in the city.

Can you do anything about my foot always hitting that bar ? Then I have to scoot foot down and then pr

No issues here..... should've bought a diesel.

The diesels have been riddled with pump,dpf,egr,and other problems. They definitely arent a Cummins

 

[Dilly’S Willy]

Don't forget the emissions side of things, making power GENERALLY creates more emissions.

Also regarding the throttle hang when lifting off after an aggressive acceleration situation, they claim it "reduces NoX output" by not allowing the throttle to snap closed". Even if this was true, wouldn't be more than a few PPM (Parts Per Million), but when you're battling Euro emissions (way more strict) you only want to spend R&D for one tune across the board.

 

[629]

While not completely relevant to the discussion.,..I drive a 3.6 1500 pickup for work. It will ping if I don’t run 89 or better when it’s hot out. While I’ve not noticed it on my gladiator under normal conditions, i did notice some when towing a trailer in hot weather.

My guess would be that the tune stock on both is marginal for 87 octane use. Especially the the 1500 which by factory numbers is supposed to make more HP. I no longer run 87 at all in either vehicle just so I have a cushion of extra octane.

 

[White Eagle]

Stellantis puts out a product that satisfies 85 percent of drivers. It’s the other 15 percent like me who realize faults or things that could have been done better. It’s no different than putting bigger wheels and tires on a Jeep. Do you need it? Why didn’t Jeep just do it from the get go? Same philosophy. Just a different side of automotive customization.

If you ever get to experience driving a vehicle stock and then driving the same vehicle that has been professionally custom tuned, you’ll see what I mean

I don’t think the product satisfies 85 percent of the drivers, I think 80% of your 85% just accept the fact new vehicles are crap and move on.

I do get 1-2 mpg less on 87 octane bought from cities with those pollution gas restrictions Like San Antonio Texas.

 

[bmpcamry09]

Don't forget the emissions side of things, making power GENERALLY creates more emissions.

Also regarding the throttle hang when lifting off after an aggressive acceleration situation, they claim it "reduces NoX output" by not allowing the throttle to snap closed". Even if this was true, wouldn't be more than a few PPM (Parts Per Million), but when you're battling Euro emissions (way more strict) you only want to spend R&D for one tune across the board.

I haven’t had any Euro customers yet. I guess they are putting tail pipe sniffers in over there and running the engine through some various RPM scenarios over there?

I have done a few California, Illinois, and New York jeeps stateside, which anre the strict ones and no one has reported any emissions issues yet. I always tell people if they think they won’t pass, flash back to stock for a few weeks and drive to get the data reset and “ready” then go get tested.

 

[Dilly’S Willy]

I haven’t had any Euro customers yet. I guess they are putting tail pipe sniffers in over there and running the engine through some various RPM scenarios over there?

I have done a few California, Illinois, and New York jeeps stateside, which anre the strict ones and no one has reported any emissions issues yet. I always tell people if they think they won’t pass, flash back to stock for a few weeks and drive to get the data reset and “ready” then go get tested.

I'm referring to the OEMs not wanting to spend more to have different tuning strategies between countries. That and if you travel and don't have access to "better" fuels they want it to run without too many issues.

Euro/CAFE standards killed off the 600cc class motorcycle in the EU, banned vehicles over 15 years of age from being able to be re-registered for public road use in cities, and will ban new ICE vehicles in 2035.

I've heard Cali does the sniffer test for many years, heck, they see a part they THINK isn't stock, you better make sure you know where the CARB sticker is and is still legible or they'll give you shit. Knew a guy who told his job he'd rather make the 2 hour drive each way vs living there with his modded car, and the cops STILL try to take it from him knowing he doesn't live in that state, but only works across the border there.

 

[1rider]

I am running the Banks pedal monster, which I know is targeting something different than your tune. Will I still be able to use this? Does it become obsolete?

 

[bmpcamry09]

I am running the Banks pedal monster, which I know is targeting something different than your tune. Will I still be able to use this? Does it become obsolete?

You wont want it or need it with tuning. We can control all that within the tune without manipulating the 5 volt pedal signal like the PM does.

 

[Rusty PW]

Can you do anything about my foot always hitting that bar ? Then I have to scoot foot down and then pr

The diesels have been riddled with pump,dpf,egr,and other problems. They definitely arent a Cummins

I've got almost 80,000 miles on my diesel. Zero issues with it. Just finished up a 3,400 trip with it. Avg 26 mpg with 37's and 3.73 oem gears.

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