Proof that 87 Octane fuel is limiting your 3.6

[1rider]

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.

Thank you, that was my thought. I have to “replenish” my Jeep account, but this is something I am interested in.

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[Stan H]

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.

And the fact your not short tripping it is probably why , I owned several bigger diesels and key to EGR and DPF survival was keeping that passive regeneration going . I think In the 5 yrs I owned my last diesel it never had to go into regen. I ran the fire out of it and the highway trips which were weekly aveaged at least 200 miles one way. I would take off from central WV and drive for example to Cumberland or to Gallapolis . Took several trips to Atlanta , Kentucky and Tennessee, if you short trip a diesel ypur gonna be in a world of hurt. I always ran fuel lubrication in my rigs. And as I read it the eco-diesels are no different. For that matter I run fuel additives in my Gasser . I believe in fuel additives . I do Not however believe in oil additives.

 

[Dilly’S Willy]

And the fact your not short tripping it is probably why , I owned several bigger diesels and key to EGR and DPF survival was keeping that passive regeneration going . I think In the 5 yrs I owned my last diesel it never had to go into regen. I ran the fire out of it and the highway trips which were weekly aveaged at least 200 miles one way. I would take off from central WV and drive for example to Cumberland or to Gallapolis . Took several trips to Atlanta , Kentucky and Tennessee, if you short trip a diesel ypur gonna be in a world of hurt. I always ran fuel lubrication in my rigs. And as I read it the eco-diesels are no different. For that matter I run fuel additives in my Gasser . I believe in fuel additives . I do Not however believe in oil additives.

That's why if it's a short trip, you need to romp on it a bit. Get those temps up and flow moving! Can't baby them.

 

[LouisvEarlleJT]

Begs the question - what was the design reason for the factory tune? I think understanding that would be beneficial.

Doesn't appear to be mpg's (since your tune would improve that, if I'm understanding). Temps? Certain RPM range?

I have no clue, this is just where my brain goes.

 

[bmpcamry09]

Begs the question - what was the design reason for the factory tune? I think understanding that would be beneficial.

Doesn't appear to be mpg's (since your tune would improve that, if I'm understanding). Temps? Certain RPM range?

I have no clue, this is just where my brain goes.

Factory tuning is set up to work for everyone no matter how bad your gas, your elevation, etc. It is set up to please the percentage of drivers who don’t care about throttle response, power delivery, refinement, etc all while meeting whatever rules they are regulated to. It is a catch all one size fits all tune.

Car guys and enthusiasts know there is always room for improvement. And it is usually in the same categories IE throttle response, transmission shifting, etc.

Custom tuning doesn’t re-write the wheel. It simply enhances what the factory fell short on. A good tuning company works within the established parameters of the software established by the OE, leaving important strategies like torque management and knock control in place, but enhancing them. Making the Jeep behave the way you want it. The base file will be what I, the tuner, feels like the Jeep should have run from the factory and is what I run in my personal Jeep.

The beauty of custom tuning is that you can set up things like throttle response, downshift/upshift response, cooling fan control, stop start behavior, and more exactly how you want. Something you can’t get at a dealership or service department.

 

[ChrisNLA]

I actually have an MPVI3 that I use to fool with my SS Camaro / LS swapped truck.

I'm slowly learning my own adjustments for the car. Been doing little things with the trans and engine.

Anyway - I have the important gear so I guess when I want to spend the money I'll have to look into this Jeep tune

 

[bmpcamry09]

I actually have an MPVI3 that I use to fool with my SS Camaro / LS swapped truck.

I'm slowly learning my own adjustments for the car. Been doing little things with the trans and engine.

Anyway - I have the important gear so I guess when I want to spend the money I'll have to look into this Jeep tune

Yeah buddy! MPVI3 works great still on these. All you’ll need is ECU unlock and bypass cable if you don’t already have Tazer or the like

 

[ChrisNLA]

Yeah buddy! MPVI3 works great still on these. All you’ll need is ECU unlock and bypass cable if you don’t already have Tazer or the like

I have a bypass too I use JSCAN for some odd and end things but been thinking about getting a Tazer as well. Might have this truck awhile...

 

[DAVECS2]

Be careful with how fast and wide you let the throttle body open in relation to fuel enrichment and cam timing. That one lever can quickly melt down an engine, as that creates transient response conditions faster that what the ecm can account for.

The fuel quality tuning stock is less than ideal, I completely agree! HP has remnants of GM's old multi-timing table architecture, but that is not exactly how the Jeep ECM is handling octane. There is an active Torque request model that is changing depending temp, knock, and misfire. You can adjust it to pull back on commanded torque maxes based on those levers and that actually skews air and timing simultaneously to get the best of the fuel you have.

The stock calibration is based around ULVE architecture, and works to minimise pumping losses and fuel over run. It is built to run at stoich of at all posible and close to no vacuum to eliminate pumping losses. The EGR exists to handle the excess NOX from funning lean all the time.

If you add fuel enrichment back in, you can improve many behaviors and reliability drastically. Your MPG will become your responsibility as the harder you drive the steeper that mpg penalty is, but the engine will have more on tap and will be more reliable.

 

[bmpcamry09]

Be careful with how fast and wide you let the throttle body open in relation to fuel enrichment and cam timing. That one lever can quickly melt down an engine, as that creates transient response conditions faster that what the ecm can account for.

The fuel quality tuning stock is less than ideal, I completely agree! HP has remnants of GM's old multi-timing table architecture, but that is not exactly how the Jeep ECM is handling octane. There is an active Torque request model that is changing depending temp, knock, and misfire. You can adjust it to pull back on commanded torque maxes based on those levers and that actually skews air and timing simultaneously to get the best of the fuel you have.

The stock calibration is based around ULVE architecture, and works to minimise pumping losses and fuel over run. It is built to run at stoich of at all posible and close to no vacuum to eliminate pumping losses. The EGR exists to handle the excess NOX from funning lean all the time.

If you add fuel enrichment back in, you can improve many behaviors and reliability drastically. Your MPG will become your responsibility as the harder you drive the steeper that mpg penalty is, but the engine will have more on tap and will be more reliable.

I appreciate your response and a lot of that is already considered during development of these tunes, but there a few of your points I want to discuss.

First, what is ULVE architecture? I’ve never heard of such a thing. I can’t even find anything on the internet with that acronym pertaining to engine tuning. I genuinely have no idea what that is and I’m super nerdy with this stuff.

To address your first concern, modern Stellantis products like this run on what is called a Neural Network. VE isn’t a thing on these. The VE maps are zeroed out. There is no MAF sensor either. Because of this, in response to throttle body opening in relation to cam timing and fuel enrichment, the neural network is fully mapped out to adapt to all of these changes naturally by itself. All possible exhaust and intake cam variations in relation to load and more are already mapped out. If you tune within these variations, there won’t be fueling issues. I have verified this with wideband implementation during development.

Most tuners, myself included, will ramp in fuel enrichment significantly faster to help with health and keep things cool. I do agree with you on that and you’re right on the money!

For example, on these from the factory, fuel enrichment is only commanded at complete wide open throttle, which is 3.8 volts throttle body command. So everything in between, even heavy load medium throttle, remains in closed loop/1.0 lambda EQ command. Which yes, is not a good thing when load is high. On all of my tunes, I have PE coming on around throttle voltages of 2.0 volts. Sometimes a little lower if a customer tells me they are towing.

The EGR system works incredibly well on these and rarely has issues. I leave all EGR functionality in place because the extra added spark advance when in EGR does a lot for keeping fuel trims in check for proper combustion, plus helping with engine response. The EGR spark adder can add in up to 14 degrees of spark when EGR is active.

Lastly, your comment about knock control and torque: what you are speaking of is very common in GM and Ford tuning, but non existent on this platform. Fords and GMs will use a “knock learn” value or an “inferred octane” value that acts as a multiplier against spark advance. Furthermore, Ford has torque and load tables directly correlated to where in that “inferred octane” range the vehicle is currently sitting at. In that sense you are correct, but that is not the way these Jeeps are set up. What is nice about out that Ford and GM logic is if you accidentally put 87 octane in the tank when custom tuned for 93, the engine will save itself.

These Jeep ECUs do not learn or pull torque over time based on knock sensor feedback. At least not to that same degree. They do have a very small “long term” knock retard area where they can constantly pull up to 6 degrees of timing, but this information will not get fed back to the torque model. In fact, on GPEC5 models since about 2023, long term knock retard is not even mapped out. I typically only see it in GPEC2 models.

The only torque modeling that can be done on these Jeeps is setting a torque ceilings and playing with the torque commanded versus torque actual airflow monitors, but HP Tuners does not have torque tables defined on this platform like they do on Ford and GM.

I want to keep this thread as accurate as possible. I appreciate your input and it sounds like you know some stuff, but not all of it directly applies to this platform.

 

[DAVECS2]

ULVE Ultra Low Vehicle Emissions. The engine was slated to go there, never got there.

I am very aware of the neural network, I have made 4 of them for this platform to work when using forced induction and the year of the vehicle.

Yes the VE table is obsolete and is now calculated via the airflow model. It would ve nice if HP could put a toggle in to run and open loop VE Table in certain conditions as the table is there and can still be used if wanted but it is an all or nothing option right now.

I personally run fuel enrichment closer to .5 and have spent a fair bit of time tuning the PRatio enrichment table, in conjunction with cam timing and airflow to allow the engine run more like a traditional engine. The only issue is the throttle body PID control is either missing parameters in HP Tuners or is less than ideal from the factory. I am in the later camp as I have battled it for years even with my previous inside connections to Chrysler.

I will digress and step down, I was just trying to throw out some stuff I have came across in dealings with the platform. Seems you have a fair grasp of whats what.

 

[bmpcamry09]

ULVE Ultra Low Vehicle Emissions. The engine was slated to go there, never got there.

I am very aware of the neural network, I have made 4 of them for this platform to work when using forced induction and the year of the vehicle.

Yes the VE table is obsolete and is now calculated via the airflow model. It would ve nice if HP could put a toggle in to run and open loop VE Table in certain conditions as the table is there and can still be used if wanted but it is an all or nothing option right now.

I personally run fuel enrichment closer to .5 and have spent a fair bit of time tuning the PRatio enrichment table, in conjunction with cam timing and airflow to allow the engine run more like a traditional engine. The only issue is the throttle body PID control is either missing parameters in HP Tuners or is less than ideal from the factory. I am in the later camp as I have battled it for years even with my previous inside connections to Chrysler.

I will digress and step down, I was just trying to throw out some stuff I have came across in dealings with the platform. Seems you have a fair grasp of whats what.

Noooo don’t digress. I love talking this stuff with people!

Oh, ULEV? Now I get what you meant.

Yeah depending on OS and ECU type, HP Tuners actually missed some critical driver demand related tables. I’ve managed to map out the main ones with .BIN file review and .XDF creation. I’ve sent these .XDFs to them and hope they continue to add them in. They have been pretty good about fixing that kind of stuff which is great.

 

[MSFTMatt]

Boy, I am really considering this the more I think about it. My issue is it's my daily driver and cannot go without it for a few weeks to get the PCM sent off to HP Tuners. I saw somewhere in the thread about buying a PCM? Does anyone have a link or recommendation on how to buy one and what the cost might be?
Also, I will be regearing to 5:38's in August and was curious if it'd be better to wait on tune till after the install. I already have a Tazer installed. Great information here for sure!!

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