BMP Calibrations Tuning - August Update

[Das_Cheese]

I have to agree. I'm used to downshifting a lot from driving other manuals that actually slowed down when you dropped a gear. The JL almost feels like you just moved it into neutral instead of dropping it a gear. And I can only imagine what that's like coming out of the high passes (ugghhh).

A little more engine braking would be awesome if it every happened but I'm not up to being the guinea pig for that.

The little 2.5L I4 is so torquey, downshifting isn't usually necessary to get good speed control on downhills, at least on the road. Or maybe that's a factor of the very limited range of the gearbox, lol

Sponsored

 

[bmpcamry09]

Does it change anything if we don't do emissions here in Colorado Springs? Or are you saying this is something internal to the jeep that gets unhappy?
Also, that does pique my curiosity. How does tweaking engine braking hurt emissions?

The ECU does a bunch of “tests” of sorts in coasting/deceleration. Specifically tests that help it determine if its emissions ready. It is likely that changing things like deceleration fuel cut off/cam overall/etc in these situations “could” prevent those monitors from passing the “tests”.

I haven’t dove in to playing with engine braking too much as frankly no one had mentioned anything until today about it. But if someone wants to mess around with it, I’m up for trying. I just cant in good conscience offer a product that could make a vehicle fail emissions simply because im a one man show and cant afford to fight the EPA. Lol

The only downside to tweaking deceleration logic is deceleration logic becomes ultra critical when off road in 4LO because you don’t want too much of it or the engine becomes unstable. So it’s really up in the air on if we can play with it much at all. Definitely would be something I would want to have a 6MT in person for as the 8AT like mine masks it quite a bit.

 

[Das_Cheese]

The ECU does a bunch of “tests” of sorts in coasting/deceleration. Specifically tests that help it determine if its emissions ready. It is likely that changing things like deceleration fuel cut off/cam overall/etc in these situations “could” prevent those monitors from passing the “tests”.

I haven’t dove in to playing with engine braking too much as frankly no one had mentioned anything until today about it. But if someone wants to mess around with it, I’m up for trying. I just cant in good conscience offer a product that could make a vehicle fail emissions simply because im a one man show and cant afford to fight the EPA. Lol

The only downside to tweaking deceleration logic is deceleration logic becomes ultra critical when off road in 4LO because you don’t want too much of it or the engine becomes unstable. So it’s really up in the air on if we can play with it much at all. Definitely would be something I would want to have a 6MT in person for as the 8AT like mine masks it quite a bit.

Gotcha. That sounds like a bit of conundrum. I'm happy to be a guinea pig whenever I can get the ball rolling. As a software engineer, this stuff fascinates me. But there's just such a huge barrier to entry, I've never really had the opportunity to look into this kind of stuff.

 

[srmitchell]

Hi Brad,
Congrats on your success so far. We've messaged before but my question is relevant to many so I figured I would ask here-
I'm a 4xe owner, Rubicon on 35's. It might get lemon lawed.

I'm shopping for a replacement rig, but my case won't be handled until December.

I care about 3 things in this order- Reliability, mpg, power.

What is your perspective on the 2.0T versus 3.6 with the tune? I want to replace my 4xe with a rubicon x, with the factory 35's and 4.56 gears.

There's 1000 threads about the 2.0 versus 3.6. But with the tune, especially if it makes more power, and if it could be potentially more reliable (from a cam/lifter perspective after your VVL tuning) I wonder if the 3.6 is the better choice for longevity. What about MPG? Or power?

I've read many replies from techs like @alphawolff and who have mixed feelings about the 2.0. I'm not a fan of mine after having three major leak repairs... one being a head gasket at 14k.

TLDR; How does the power, MPG and overall drivability with your 3.6 tune compare to the 2.0t?

Thanks and sorry if my question is confusing.

Sean

 

[alphawolff]

Hi Brad,
Congrats on your success so far. We've messaged before but my question is relevant to many so I figured I would ask here-
I'm a 4xe owner, Rubicon on 35's. It might get lemon lawed.

I'm shopping for a replacement rig, but my case won't be handled until December.

I care about 3 things in this order- Reliability, mpg, power.

What is your perspective on the 2.0T versus 3.6 with the tune? I want to replace my 4xe with a rubicon x, with the factory 35's and 4.56 gears.

There's 1000 threads about the 2.0 versus 3.6. But with the tune, especially if it makes more power, and if it could be potentially more reliable (from a cam/lifter perspective after your VVL tuning) I wonder if the 3.6 is the better choice for longevity. What about MPG? Or power?

I've read many replies from techs like @alphawolff and who have mixed feelings about the 2.0. I'm not a fan of mine after having three major leak repairs... one being a head gasket at 14k.

TLDR; How does the power, MPG and overall drivability with your 3.6 tune compare to the 2.0t?

Thanks and sorry if my question is confusing.

Sean

The 3.6l is a better designed engine in just about every way. The only drawback was that ungodly hesitation issue which annoyed Brad enough to fix it himself. If you can't afford a 392 then get the 3.6l.

I say this as someone who currently has a 2.0L sitting in his driveway (against my wishes)

 

[GabeBoyTheGreat]

I have to agree. I'm used to downshifting a lot from driving other manuals that actually slowed down when you dropped a gear. The JL almost feels like you just moved it into neutral instead of dropping it a gear. And I can only imagine what that's like coming out of the high passes (ugghhh).

A little more engine braking would be awesome if it every happened but I'm not up to being the guinea pig for that.

Interesting. I have not noticed an issue with engine braking on the highway. Yea, it's not as signifcant as my 4.0l TJ or 6.2l Camaro, but that is to be expected from those larger engines.

The only thing that I have noticed is that there is a slight delay between downshifting and fuel cutoff, and this delay can be felt. However, the delay isn't significant enough IMO to mess with tuning.

Once the fuel cuts off, I am not sure that any amount of tuning can "improve" engine braking. You can check if fuel is cutting off by looking at your real-time MPG. If it reads 99, then fuel is most likely cut off. What gears and tires are you running?

All of that said, I HAVE noticed some situations while offroading where my engine will not engine brake correctly. It will let the engine run up to 2k RPM, then it seems to suddenly cut fuel and drop down to 1k RPM, at which point it starts speeding up again. This cycle will keep repeating itself. However, trying to replicate the conditions in which this occurs is difficult, which is why I haven't been able to datalog it.

 

[LSJKU]

Interesting. I have not noticed an issue with engine braking on the highway. Yea, it's not as signifcant as my 4.0l TJ or 6.2l Camaro, but that is to be expected from those larger engines.

The only thing that I have noticed is that there is a slight delay between downshifting and fuel cutoff, and this delay can be felt. However, the delay isn't significant enough IMO to mess with tuning.

Once the fuel cuts off, I am not sure that any amount of tuning can "improve" engine braking. You can check if fuel is cutting off by looking at your real-time MPG. If it reads 99, then fuel is most likely cut off. What gears and tires are you running?

All of that said, I HAVE noticed some situations while offroading where my engine will not engine brake correctly. It will let the engine run up to 2k RPM, then it seems to suddenly cut fuel and drop down to 1k RPM, at which point it starts speeding up again. This cycle will keep repeating itself. However, trying to replicate the conditions in which this occurs is difficult, which is why I haven't been able to datalog it.

I am planning a trip out west, hopefully early fall. I will be sure and bring my MPVI4 and try to get a datalog with downhill engine braking. I want to recreate what you describe before saying anything else. I don't notice it, or I haven't tried to on the hills around Kerrville.

And you are correct, I was comparing the 3.6L JL engine braking to other cars with much bigger engines, like my 2SS 1LE. That may not be a fair comparison.

 

[bmpcamry09]

Hi Brad,
Congrats on your success so far. We've messaged before but my question is relevant to many so I figured I would ask here-
I'm a 4xe owner, Rubicon on 35's. It might get lemon lawed.

I'm shopping for a replacement rig, but my case won't be handled until December.

I care about 3 things in this order- Reliability, mpg, power.

What is your perspective on the 2.0T versus 3.6 with the tune? I want to replace my 4xe with a rubicon x, with the factory 35's and 4.56 gears.

There's 1000 threads about the 2.0 versus 3.6. But with the tune, especially if it makes more power, and if it could be potentially more reliable (from a cam/lifter perspective after your VVL tuning) I wonder if the 3.6 is the better choice for longevity. What about MPG? Or power?

I've read many replies from techs like @alphawolff and who have mixed feelings about the 2.0. I'm not a fan of mine after having three major leak repairs... one being a head gasket at 14k.

TLDR; How does the power, MPG and overall drivability with your 3.6 tune compare to the 2.0t?

Thanks and sorry if my question is confusing.

Sean

Hey Sean! I love the 3.6 personally. I also owned a 2.0 as well for about two years. Stock for stock the 2.0 is stronger off the line, but my 2.0 was far from reliable. Before 50,000 miles I had to replace the timing chain/tensioner for a nasty rattle and the crankcase ventilation unit under the intake for an oil leak, the latter being out of warranty.

The 2.0 produces too much heat for me to want to push them harder with tuning. At some point, I’ll do something for them. In the mean time, I only do transmission tuning on them.

The 3.6 is a joy when tuned. It really is night and day. And I strongly feel eliminating high lift mode like I do on all my tunes now can help prolong camshaft life. But for what it’s worth; I’ve owned 4 vehicles with the PUG engine and with probably 160,000 miles between the 4 of them, I’ve never had a failure. I personally love the 3.6. It’s relatively easy and affordable to work on. It actually cracks me up when people freak out over the cam shafts because it’s really not that hard of a job to replace the camshafts on these, timing cover doesn’t even need to be removed. In the master tech world it’s considered a gravy job. Forums can make things seem way worse than they are.

As far as power and MPG, expect on 87 octane raw increases of 10 HP/10TQ, but a big shift in the amount of torque available under 3000 RPM. With 93, those gains are even larger, expect 30 HP/30TQ. Most of my customers report a 1-2 MPG improvement once tuned as well. On my personal Jeep I see maybe .5-1 MPG improvement, but I drive the crap out of my Jeep since I’m always developing/refining/improving or testing stuff out.

 

[srmitchell]

Hey Sean! I love the 3.6 personally. I also owned a 2.0 as well for about two years. Stock for stock the 2.0 is stronger off the line, but my 2.0 was far from reliable. Before 50,000 miles I had to replace the timing chain/tensioner for a nasty rattle and the crankcase ventilation unit under the intake for an oil leak, the latter being out of warranty.

The 2.0 produces too much heat for me to want to push them harder with tuning. At some point, I’ll do something for them. In the mean time, I only do transmission tuning on them.

The 3.6 is a joy when tuned. It really is night and day. And I strongly feel eliminating high lift mode like I do on all my tunes now can help prolong camshaft life. But for what it’s worth; I’ve owned 4 vehicles with the PUG engine and with probably 160,000 miles between the 4 of them, I’ve never had a failure. I personally love the 3.6. It’s relatively easy and affordable to work on. It actually cracks me up when people freak out over the cam shafts because it’s really not that hard of a job to replace the camshafts on these, timing cover doesn’t even need to be removed. In the master tech world it’s considered a gravy job. Forums can make things seem way worse than they are.

As far as power and MPG, expect on 87 octane raw increases of 10 HP/10TQ, but a big shift in the amount of torque available under 3000 RPM. With 93, those gains are even larger, expect 30 HP/30TQ. Most of my customers report a 1-2 MPG improvement once tuned as well. On my personal Jeep I see maybe .5-1 MPG improvement, but I drive the crap out of my Jeep since I’m always developing/refining/improving or testing stuff out.

Great info. I really appreciate your insight. I obviously wouldn't buy a JL on 35's just for fuel economy, it is just good to know what I should expect. My wife doesn't love the idea of ditching the hybrid.

I share your concern about heat. I was surprised to see how hot my 2.0 was getting on a recent trip to the sierras. 235 was the highest I saw on the oil side.

My old WK2 Trailhawk had a 3.6 and it was great.

 

[Dave M]

. . . I love the 3.6 personally . . . The 3.6 is a joy when tuned. . .

I like my 3.6 V6 too, Brad's tune makes it run like a 3/4 V8.

Sponsored