HP Tuners for 3.6 models - Fixing what Jeep won’t

[jadmt]

really cool to see guys do this. It is out of my comfort level at least until my 24's warranty is getting close to ending and the jeep is proving to not need to go back to the dealership...I had a big enough issue early on that I am still not totally trusting it won't be back but would love another 30-50hp/tq

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[YBABRAT]

If anyone can chime in, I am looking for a summary of other tune related things you would like to see improved on your JL. Here is what I plan on working on:

-Creating a more linear throttle response, not so spongy
-Changing when and where the torque converter locks up, i think lockup in 2nd gear is a bit extreme.
-Disabling auto start stop so button no longer needs to be pressed every start up.
-Allowing the trans to ride in 4th and 5th gear more in town not being so eager to get into high gear to help with engine bogging down.
-Changing cooling fan activation points, because coolant temps get high in summer.
-Changing VVT and cam timing to help with low end grunt around town.
-Taking some of the slop out of normal in town shifting, shifting seems a little too sluggish at part throttle, seems okay at wide open throttle might tweak WOT just a little bit though.
-Truely optimizing spark timing for those who only run 87 fuel, sure Jeep says it's "safe" and sure it is by the book, but trust me, I've tuned enough modern vehicles to know that your enigne is borderline detonating on 87 fuel no matter what your manufacturer says, and I'd rather not have the engine ping and bouncing off the knock sensors.
-Maybe add about 20-30 HP with some extra timing for those willing to run premium fuel.

I never have seen low rpm hesitation with my engine. Though I went with banks pedal monster ro calibrate throttle to be linear for economy driving. Engine wants to go (jumpy with input). Most drive by wire are hesitatant with input at low RPM, but never seen it with my Jeep. I was getting around 17 MPG at best with my driving habits in the mountaians. With pedal monster I get better economy from toning down throttle responce and get 20+MPG and still have excellent performance. Though I am the only one with a 2nd gen Pentastar that runs better than what others complain about... Either oiling or performance issues.

 

[YBABRAT]

All of this sounds good to me. I found this thread about the RPM Extreme Fan controller. In the OP, there is an image that shows the fan settings based on temperature. That would probablybe a good baseline: https://www.jlwranglerforums.com/forum/threads/rpm-fan-controller-results-on-off-road.128374/

Looks like the fan kicks to 100% at 218+ which seems reasonable to me. I would like to keep my temps below 220 if possible. I think the stock setting is like 232 for 100% fan.

I would also recommend watching this video from Livernois showcasing their dyno results from their GPEC-2 tune:

It would be nice if you could get rid of that torque dip between 4k and 5k RPMs like Livernois did.

Any torque improvements for RPMs < 2k would also be welcomed.

When I drove cross country, and made it through UT, NV and CA around 100°F engine ran fine with coolent around 225°F, Oil was around 230°F, tranny 215°F. This winter ran a radiator blanket to keep cookent around 225°F between outside temps of 0°F to 50°F. See no reason for a fan controller.

 

[GabeBoyTheGreat]

When I drove cross country, and made it through UT, NV and CA around 100°F engine ran fine with coolent around 225°F, Oil was around 230°F, tranny 215°F. This winter ran a radiator blanket to keep cookent around 225°F between outside temps of 0°F to 50°F. See no reason for a fan controller.

That's because you are driving on the highway with natural airflow. When driving <5 MPH on trails, my temps will reach 230 consistently. That isn't far from dangerously high temps.

 

[azjl#3]

I’m about 90 percent positive after looking at both GPEC2 and GPEC5 files that this hesitation is due to the way the intake variable cam timing tables are set up, paired with the EGR system and the accompanying spark timing tables that are EGR modifiers. I think the EGR effect paired with wack timing tables are causing a false knock detonation event that is making the engine suddenly pull timing. But I’ll know for sure here in about a week when my PCM is back and I can build a good datalog channel and do some driving.

I agree, and my simple for now solution, I'm using 87 or 91 octane if its warmer . MPG is up 1.5mpg, "feels" smoother better.

 

[bmpcamry09]

I have been considering tunes for our '22 6 speed 2 door, and they are in the running. I'm concerned that I won't be able to have anyone tweak it, their jail broken version of the PCM is only open to their tuning afterwards. Diablosport does the same thing. They crack the security and install their own basically.

I'd love to tune my own stuff, but it really does need time, a dyno and all the tuning equipment. I did this several years ago at a specialized performance shop/machine shop. I build motor stuff on the side still, performance work, mostly cylinder head work now for drag racers and hot rodders. I'm not doing cast iron anymore though. Too many guys wanting to give me 55-65 year old cast iron wanting performance on par with modern heads, that have been heat cycled and overheated for 55-65 years.

I'm back to being a Euro car master tech, it pays better. Been working on cars since, well, I'll just say a long time! Coming up on 50 years. I was into high performance stuff in 1982, so I'm really impressed with how much we can do on the modern vehicles that we had to try to crutch back then.

Cylinder pressure at high throttle/loading at lower RPM wasn't a thing, because high performance cams usually had overlap and bled pressure at the lower RPM. You kept static compression down a bit with lower duration cams so that you didn't detonate. It was fixed cam timing and the lobes were married in relation to each other.

I attended the School of Automotive Machinists some years ago, and that's essentially a NASCAR and NHRA feeder school. I can build some nasty stuff pretty much budget limited. But the modern cars with all the functions for modern drivability and emissions are a balancing act at all times due to fuels and the huge range of operation. I work on Euro stuff and we're dancing with detonation on compound supercharged engines. You can put a 91 octane requirement on at the factory and you will ALWAYS have people that want to run a high static compression/boosted engine on 87 octane. The tuning is crutched as heck to meet emissions on crap fuel.

It took me about 3 expensive training courses, monthly subscriptions through Evan’s Academy, and in person tuning about 20 vehicles before I got comfortable with it. I developed on all my own vehicles first then worked my way out. Now I can’t stop learning and it’s addicting. Lol

Dont be bashful! Most big companies do remote tuning and dynos aren’t even needed unless you’re really pushing limits. Most modern ECUs have horsepower and torque calculations and can give you a close representation of gains without a dyno.

 

[Badunit]

Can the hanging throttle be tuned out? This is when you punch it then let off quickly but it keeps the throttle on, then slowly backs it off. It happens with the automatic, I don't know about the manual. It is dangerous that it keeps accelerating on its own with foot off the throttle.

 

[bmpcamry09]

Can the hanging throttle be tuned out? This is when you punch it then let off quickly but it keeps the throttle on, then slowly backs it off. It happens with the automatic, I don't know about the manual. It is dangerous that it keeps accelerating on its own with foot off the throttle.

Maybe. Usually spark timing and DFCO (deceleration fuel cut off) contribute to this, but there are some friction torque tables that can possibly come in to play. I’ll check it out.

 

[GabeBoyTheGreat]

Can the hanging throttle be tuned out? This is when you punch it then let off quickly but it keeps the throttle on, then slowly backs it off. It happens with the automatic, I don't know about the manual. It is dangerous that it keeps accelerating on its own with foot off the throttle.

Definitely happens with the manual. AKA "rev hang"

 

[YBABRAT]

That's because you are driving on the highway with natural airflow. When driving <5 MPH on trails, my temps will reach 230 consistently. That isn't far from dangerously high temps.

Yes, but... in 100°F heat, going up hill on twisty mountain ranges, at 20MPH, when pushing like your racing pikes peak is pretty close. The some times I had the fan kick into high making my way into stop lights and parking lots before cool down. One thing about Pentastar v2.0 they run better at 200°F and above at engine temps. Even with 225°F my gauge near the fuel level never really showed coolent being too hot to worry about. In winter conditions, i get an extra 1.5MPG with running 225°F coolent temps. Which only can be done with a radiator blanket.

 

[alphawolff]

I’m about 90 percent positive after looking at both GPEC2 and GPEC5 files that this hesitation is due to the way the intake variable cam timing tables are set up, paired with the EGR system and the accompanying spark timing tables that are EGR modifiers. I think the EGR effect paired with wack timing tables are causing a false knock detonation event that is making the engine suddenly pull timing. But I’ll know for sure here in about a week when my PCM is back and I can build a good datalog channel and do some driving.

Really excited to see what you come up with.

Something I did early on was unplug the EGR for testing, and the issue still occurs with it disconnected. I don't think the EGR is the cause of it, but it's possible it's having a minor addition to it. The EGR loves being engaged in those low-load cruise situations.

With regards to the first video (PCM removal) I would add a step to clean around the PCM. With the GPEC2A where the connectors are on the side, if you Jeep is actually taken off road you get a lot of dirt and grit around the connectors. And so the levered slides do not want to operate and the connector housing need to come apart to get the locks off. We took an hour to undo the connectors the first time.

Dealer tech trick here; wd-40 into the locks on the sides locks, then wiggle the harness as you slowly back the lock off. Do not use any force, just keep wiggling.

This tip was brought to you by years of frustration, pain, and suffering.

Definitely happens with the manual. AKA "rev hang"

I hate it. This + the high idle when cold are beyond frustrating.

I never have seen low rpm hesitation with my engine. Though I went with banks pedal monster ro calibrate throttle to be linear for economy driving. Engine wants to go (jumpy with input). Most drive by wire are hesitatant with input at low RPM, but never seen it with my Jeep. I was getting around 17 MPG at best with my driving habits in the mountaians. With pedal monster I get better economy from toning down throttle responce and get 20+MPG and still have excellent performance. Though I am the only one with a 2nd gen Pentastar that runs better than what others complain about... Either oiling or performance issues.

A throttle controller will definitely reduce the chance of this ever occurring, as it only happens under very precise throttle, load, and cruise conditions. Changing the throttle input (i.e., more throttle) will significantly reduce the effect. I started driving mine at 2.5-3.5k RPM all the time to reduce the chances of it happening, for example.

 

[Traveller128]

Dealer tech trick here; wd-40 into the locks on the sides locks, then wiggle the harness as you slowly back the lock off. Do not use any force, just keep wiggling.

This tip was brought to you by years of frustration, pain, and suffering.

Try doing this, but with silicone spray, mainly on the larger connectors with the two sliding locks. I use PB Blaster sometimes but the silicone spray seems to lubricate the plastic parts a little better on the big connectors. Helps lubricate plastic to plastic interfaces with grit in them. A bit in each side, let it flash off, then do the wiggle trick like you said. Been doing that for a number of years. Similar solution to the problem.

I hate large connectors with flimsy bails.

 

[dstevens]

Radiator fan operation: No one is forcing you to lower the operational temperature of the fans, but I'll give one scenario where the behavior drives me nuts. Off road crawling, especially where there is fine dust. What happens is the coolant gets to 221F, the fan comes on full with the noise of a small jet engine which blows dust everywhere and you also cannot hear your spotter. 1 minute later the fan cycles off, only to repeat the same thing 1 minute after that. My next point is that if Stellantis wanted the engine to run at 220F they would have put a higher temperature thermostat in - it's just the fan operation.

Rev hang: deliberate operation to prevent the spike in oxides of nitrogen when the throttle is closed. And also on port injection engines there is a spike of hydrocarbons when the intake manifold vacuum increases, vaporizing the port wall film. So the throttle is not completely closed and the injector is kept on for a while. Doesn't bother me on ATs but on MTs can be a drag.

Throttle controller: same behavior can be replicated by altering the driver demand tables. Some people swear by them but they just alter the electrical output from the throttle pedal.

 

[wanted]

If anyone can chime in, I am looking for a summary of other tune related things you would like to see improved on your JL. Here is what I plan on working on:

-Creating a more linear throttle response, not so spongy
-Changing when and where the torque converter locks up, i think lockup in 2nd gear is a bit extreme.
-Disabling auto start stop so button no longer needs to be pressed every start up.
-Allowing the trans to ride in 4th and 5th gear more in town not being so eager to get into high gear to help with engine bogging down.
-Changing cooling fan activation points, because coolant temps get high in summer.
-Changing VVT and cam timing to help with low end grunt around town.
-Taking some of the slop out of normal in town shifting, shifting seems a little too sluggish at part throttle, seems okay at wide open throttle might tweak WOT just a little bit though.
-Truely optimizing spark timing for those who only run 87 fuel, sure Jeep says it's "safe" and sure it is by the book, but trust me, I've tuned enough modern vehicles to know that your enigne is borderline detonating on 87 fuel no matter what your manufacturer says, and I'd rather not have the engine ping and bouncing off the knock sensors.
-Maybe add about 20-30 HP with some extra timing for those willing to run premium fuel.

I feel like this is almost everything I've been looking for.
As it stands, I've run 91 exclusively since I purchased the jeep as I truly don'ttrust running lower octane fuel in any vehicle I've owned. I love the idea of getting a bump in power.

I feel like these ought to have a little more in them than they do. Definitely want more low-end torque.

 

[wanted]

Livernois has been able to move the torque curve to the left a bit so there's more low end. They've also got something called a "tow" tune that I might be doing on ours.

They got rid of the TQ dip and made a smooth curve which is meaningful for towing and passing already.

Their tune defaults ESS to off but allows you to manually turn it on if you want.

Tunes for manual and auto trans, 87, 91, 93, E85 available plus the "tow" tune which I find interesting.

I wouldn't be opposed to going this route for the 24, but haven't seen anything on their site about it.

BTW, good to know it wasn't my imagination about the torque dip. I'm so used to driving higher power vehicles as my daily drivers that I sometimes lack frame of reference on if some of the things I feel on vehicles like these are normal or not.

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