Turbo Lag mostly as... Transmission Lag!

[jmccorm]

This may be a programming issue where, in your instance, it's not optimal and really shows an issue.

Good points all the way around. And throttle will be even more disconnected from the accelerator because the vehicle is rev-matching into it's new gear.

Let me share some of the more recent logs. The times, at least, are improved now that I've optimized the tire size:

Log Excerpt #1: Flooring the accelerator pedal from 36 MPH (transmission shifts from 6th to 3rd), acceleration 0.9 seconds later:

96430.5 ACCL: 9% (VALVE 10%) RPM: 1536 GEAR: D6 DOM: 7603.6mi MPH: 37.19
96430.6 ACCL: 9% (VALVE 9%) RPM: 1525 GEAR: D6 DOM: 7603.6mi MPH: 37.11
96430.7 ACCL: 10% (VALVE 9%) RPM: 1528 GEAR: D6 DOM: 7603.6mi MPH: 37.09
96430.8 ACCL: 10% (VALVE 9%) RPM: 1537 GEAR: D6 DOM: 7603.6mi MPH: 37.08
96430.9 ACCL: 10% (VALVE 10%) RPM: 1530 GEAR: D6 DOM: 7603.6mi MPH: 37.08
96431.0 ACCL: 10% (VALVE 10%) RPM: 1534 GEAR: D6 DOM: 7603.6mi MPH: 37.06
96431.1 ACCL: 10% (VALVE 11%) RPM: 1538 GEAR: D6 DOM: 7603.6mi MPH: 37.13
96431.2 ACCL: 10% (VALVE 11%) RPM: 1535 GEAR: D6 DOM: 7603.6mi MPH: 37.09
96431.3 ACCL: 10% (VALVE 11%) RPM: 1531 GEAR: D6 DOM: 7603.6mi MPH: 37.04
96431.4 ACCL: 10% (VALVE 11%) RPM: 1529 GEAR: D6 DOM: 7603.6mi MPH: 37.05
96431.5 ACCL: 53% (VALVE 20%) RPM: 1528 GEAR: D6 DOM: 7603.6mi MPH: 37.02
96431.6 ACCL: 77% (VALVE 25%) RPM: 1587 GEAR: D3 DOM: 7603.6mi MPH: 37.10
96431.7 ACCL: 80% (VALVE 34%) RPM: 1673 GEAR: D3 DOM: 7603.6mi MPH: 37.16
96431.8 ACCL: 80% (VALVE 38%) RPM: 1761 GEAR: D3 DOM: 7603.6mi MPH: 37.26
96431.9 ACCL: 84% (VALVE 42%) RPM: 1976 GEAR: D3 DOM: 7603.6mi MPH: 37.27
96432.0 ACCL: 88% (VALVE 46%) RPM: 2322 GEAR: D3 DOM: 7603.6mi MPH: 37.17
96432.1 ACCL: 92% (VALVE 51%) RPM: 2758 GEAR: D3 DOM: 7603.6mi MPH: 37.15
96432.2 ACCL: 92% (VALVE 57%) RPM: 3168 GEAR: D3 DOM: 7603.6mi MPH: 37.19
96432.3 ACCL: 92% (VALVE 68%) RPM: 3324 GEAR: D3 DOM: 7603.6mi MPH: 37.26
96432.4 ACCL: 92% (VALVE 76%) RPM: 3581 GEAR: D3 DOM: 7603.6mi MPH: 37.86
96432.5 ACCL: 90% (VALVE 83%) RPM: 3575 GEAR: D3 DOM: 7603.6mi MPH: 38.57
96432.6 ACCL: 89% (VALVE 89%) RPM: 3543 GEAR: D3 DOM: 7603.6mi MPH: 39.34
96432.7 ACCL: 88% (VALVE 91%) RPM: 3586 GEAR: D3 DOM: 7603.6mi MPH: 40.28
96432.8 ACCL: 88% (VALVE 91%) RPM: 3594 GEAR: D3 DOM: 7603.6mi MPH: 41.04
96432.9 ACCL: 88% (VALVE 92%) RPM: 3639 GEAR: D3 DOM: 7603.6mi MPH: 41.52
96433.0 ACCL: 87% (VALVE 90%) RPM: 3693 GEAR: D3 DOM: 7603.6mi MPH: 42.03
96433.1 ACCL: 87% (VALVE 91%) RPM: 3731 GEAR: D3 DOM: 7603.6mi MPH: 42.48
96433.2 ACCL: 87% (VALVE 92%) RPM: 3807 GEAR: D3 DOM: 7603.6mi MPH: 43.28
96433.3 ACCL: 88% (VALVE 93%) RPM: 3855 GEAR: D3 DOM: 7603.6mi MPH: 44.00
96433.4 ACCL: 89% (VALVE 93%) RPM: 3918 GEAR: D3 DOM: 7603.6mi MPH: 44.55

Log Excerpt #2: Flooring the accelerator pedal from 50 MPH (transmission shifts from 8th to 7th, then 7th to 5th, and then shifts from 5th to 3rd), acceleration 1.1 seconds later:

96742.2 ACCL: 22% (VALVE 23%) RPM: 1750 GEAR: D7 DOM: 7605.7mi MPH: 50.56
96742.3 ACCL: 21% (VALVE 23%) RPM: 1753 GEAR: D7 DOM: 7605.7mi MPH: 50.60
96742.4 ACCL: 21% (VALVE 23%) RPM: 1755 GEAR: D7 DOM: 7605.7mi MPH: 50.56
96742.5 ACCL: 20% (VALVE 22%) RPM: 1752 GEAR: D7 DOM: 7605.7mi MPH: 50.61
96742.6 ACCL: 20% (VALVE 21%) RPM: 1751 GEAR: D7 DOM: 7605.7mi MPH: 50.55
96742.7 ACCL: 20% (VALVE 21%) RPM: 1752 GEAR: D7 DOM: 7605.7mi MPH: 50.59
96742.8 ACCL: 19% (VALVE 22%) RPM: 1755 GEAR: D7 DOM: 7605.8mi MPH: 50.59
96742.9 ACCL: 20% (VALVE 21%) RPM: 1755 GEAR: D8 DOM: 7605.8mi MPH: 50.59
96743.0 ACCL: 19% (VALVE 21%) RPM: 1757 GEAR: D8 DOM: 7605.8mi MPH: 50.54
96743.1 ACCL: 19% (VALVE 21%) RPM: 1782 GEAR: D8 DOM: 7605.8mi MPH: 50.54
96743.2 ACCL: 55% (VALVE 24%) RPM: 1799 GEAR: D8 DOM: 7605.8mi MPH: 50.55
96743.3 ACCL: 80% (VALVE 37%) RPM: 1891 GEAR: D7 DOM: 7605.8mi MPH: 50.62
96743.4 ACCL: 83% (VALVE 41%) RPM: 1892 GEAR: D5 DOM: 7605.8mi MPH: 50.70
96743.5 ACCL: 81% (VALVE 47%) RPM: 1882 GEAR: D5 DOM: 7605.8mi MPH: 50.72
96743.6 ACCL: 82% (VALVE 51%) RPM: 1984 GEAR: D5 DOM: 7605.8mi MPH: 50.81
96743.7 ACCL: 84% (VALVE 55%) RPM: 2237 GEAR: D5 DOM: 7605.8mi MPH: 50.89
96743.8 ACCL: 86% (VALVE 60%) RPM: 2485 GEAR: D5 DOM: 7605.8mi MPH: 50.88
96743.9 ACCL: 89% (VALVE 68%) RPM: 2818 GEAR: D5 DOM: 7605.8mi MPH: 50.99
96744.0 ACCL: 90% (VALVE 78%) RPM: 3169 GEAR: D3 DOM: 7605.8mi MPH: 51.16
96744.1 ACCL: 86% (VALVE 87%) RPM: 3587 GEAR: D3 DOM: 7605.8mi MPH: 51.28
96744.2 ACCL: 83% (VALVE 90%) RPM: 4135 GEAR: D3 DOM: 7605.8mi MPH: 51.38
96744.3 ACCL: 83% (VALVE 85%) RPM: 4615 GEAR: D3 DOM: 7605.8mi MPH: 51.57
96744.4 ACCL: 80% (VALVE 85%) RPM: 4714 GEAR: D3 DOM: 7605.8mi MPH: 52.35
96744.5 ACCL: 81% (VALVE 85%) RPM: 4689 GEAR: D3 DOM: 7605.8mi MPH: 52.99
96744.6 ACCL: 80% (VALVE 85%) RPM: 4721 GEAR: D3 DOM: 7605.8mi MPH: 53.57
96744.7 ACCL: 83% (VALVE 87%) RPM: 4775 GEAR: D3 DOM: 7605.8mi MPH: 54.28
96744.8 ACCL: 81% (VALVE 85%) RPM: 4824 GEAR: D3 DOM: 7605.8mi MPH: 54.96
96744.9 ACCL: 80% (VALVE 87%) RPM: 4883 GEAR: D3 DOM: 7605.8mi MPH: 55.59
96745.0 ACCL: 80% (VALVE 88%) RPM: 4933 GEAR: D3 DOM: 7605.8mi MPH: 56.30
96745.1 ACCL: 78% (VALVE 88%) RPM: 4978 GEAR: D3 DOM: 7605.8mi MPH: 56.93
96745.2 ACCL: 78% (VALVE 89%) RPM: 5050 GEAR: D3 DOM: 7605.8mi MPH: 57.64
96745.3 ACCL: 77% (VALVE 87%) RPM: 5090 GEAR: D3 DOM: 7605.8mi MPH: 58.31

Overall? I think I share many of your thoughts. Well said! For better or for worse, this would tend to leave it at Jeep's discretion whether they wanted to pursue or not. I won't hold my breath, but I'll hope for product improvement.

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[Cowboy from hell]

Shoulda bought the 6 peed MT......

 

[DavidArmen]

Very interesting. My 2021 JLUR 3.6 etorque has almost no lag when I go full throttle. I’m honestly amazed at how quickly the zf8 downshifts. I would give a very rough guess of about 0.2-0.3 seconds between flooring it and the jeep ripping off

 

[The Fixer]

Very interesting. My 2021 JLUR 3.6 etorque has almost no lag when I go full throttle. I’m honestly amazed at how quickly the zf8 downshifts. I would give a very rough guess of about 0.2-0.3 seconds between flooring it and the jeep ripping off

My wife's '18 with the 3.6/8-speed does not have the same hesitation as my '18 2.0T/8-speed. It's definitely a programming issue related to the 2.0....what the reasoning is behind it, I haven't a clue.

 

[jmccorm]

A FINAL UPDATE:

As recommended, I installed a throttle controller.

Because it was a prominent brand, and because it was listed on Amazon (making for a hassle-free return in case it was not the cure), I went with the Pedal Commander PC78. Installation was obvious and easy, and I started at the City +2 setting, where it remains.

And the initial problem? Unaffected. It still remains. Suddenly flooring the gas pedal still takes a good 1.0 or 1.1 seconds before any real acceleration begins. HOWEVER...

I noticed that all the other times I gave the vehicle a bit of gas, it was always far more responsive. Very much so. In fact... if I had to choose a word, I would say that the vehicle is much more "spirited" than it ever was before.

What now? At this point, the original issue seems moot because I'm no longer having to smash the gas pedal to get a quick burst of acceleration. In fact, I'd go further to say that with this problem to the side, this is exactly how I would have wanted the vehicle to have come from the factory.

While Jeep still has a substantiated issue (apparently between the automatic transmission and the 2.0T engine without eTorque) any further pursuit of it would be a waste of time.

TL;DNR: Problem technically remains but in all actuality, a good throttle controller helps the driver avoid any need to jump to a wide-open-throttle in order to get a quick response from the vehicle. Damn good workaround!

I can highly endorse a throttle controller to any other 2.0T owner who seems concerned or disappointed by their vehicle's lack of responsiveness (in general, or in this same specific situation).

 

[jmccorm]

This thread has been on my mind for a while. My thesis is that what most people claim to experience as "turbo lag" in the 2.0T engine isn't actually turbo lag at all, but actually something different... transmission lag!

I documented my findings with a CAN bus logger, but a normal Wrangler owner can pretty much discover the same thing by turning on the "Current Gear Indicator" and watch what happens with their current gear as they experience lag.

The steps to reproduce the problem (at least on my '21 2.0T JLUR) are as follows:

1. Go exactly 41 MPH on flat terrain (cruise control if needed) until it puts you into 7th gear.​

2. Very quickly FLOOR the accelerator (like it's an emergency). Stomp it to the ground.​

3. Wait. No more acceleration, no sound, no nothing. Wait. Wait. Watch your current gear indicator if you've got that set up.​

4. The vehicle eventually completes the shift into 3rd gear and you start to accelerate, somewhere between 1 and 1.5 seconds after you commanded it.​

To recap:
I've created a series of steps to reproduce the problem, and my dealer has been able to replicate the problem in my own vehicle and another vehicle of the same make and model, and that I've got a substantiated theory as to the actual cause of the lag in the transmission.

Resolution?
Now that I've got the time and the energy, I think I'm willing to chase this down with Jeep to see if they concur and are willing to address the issue.

At this point, does anyone have a substantial reason why I should not pursue getting this issue officially identified and resolved with Jeep for all similarly affected vehicles? (I figure it's to their benefit, too, to get rid of this lag issue. It certainly doesn't help sell vehicles when someone hits it on a test drive.)

 

[longfiredragon]

This issue could be annoying. I have owned many turbo vehicles. This little hurricane 2.0 is one of the best driving turbos IMHO. And, my 8 speed trans shifts excellent, sorry to hear yours doesn't.

When my jeep was stock at around 35 to 40 miles per hour if you floored it the transmission would downshift and turbo would spool up so fast it would chirp the rear tires.

This may help. Now I have a Superchips tune. It only adds 18 HP and 29 lbs of torque. But the more noticeable changes are the way it changed the fuel and boost curve. Really, really fun to drive now. Just be careful on wet roads.

 

[Obi Wan]

I see everyone looking to inline throttle controllers, but not one person mentioned this thread talking about the 2.0 ECU tuning by @EUROCOMPULSION

This tune seems to tackle both the turbo lag and the transmission shifting issues. Give it a read if you haven't. Once they give an update to the new onboard tuning system, I'll most likely be going that route.

 

[JP29]

I see everyone looking to inline throttle controllers, but not one person mentioned this thread talking about the 2.0 ECU tuning by @EUROCOMPULSION

This tune seems to tackle both the turbo lag and the transmission shifting issues. Give it a read if you haven't. Once they give an updated to the new onboard tuning system, I'll most likely be going that route.

+1 for the EC tune. When they give some more info on their Phase 2 version, I'll likely go in on it and report back.

 

[jmccorm]

This tune seems to tackle both the turbo lag and the transmission shifting issues. Give it a read if you haven't. Once they give an update to the new onboard tuning system, I'll most likely be going that route.

You're right!

"With the tune changes, going above 75% throttle it will automatically downshift to the ideal torque range for immediate get-up and go, whereas before it seemed to hunt for where it needed to be, and then would be very peaky."​

That's a pretty good and consistent description of the problem. You floor it, it hunts for a while, then you [eventually, while it hunts...] find yourself in the high RPM range of a much lower gear.

 

[AnnDee4444]

Put the transmission in manual mode to feel the turbo lag... which there isn't much.

Also should mention that boost threshold ≠ turbo lag.

 

[jmccorm]

This tune seems to tackle both the turbo lag and the transmission shifting issues. Give it a read if you haven't. Once they give an update to the new onboard tuning system, I'll most likely be going that route.

You know, I just put something else together.

In that thread, he said that the "transmission tune" wasn't actually done by putting new numbers into the TCM, but into the PCM itself (the engine's ECU). And the PCM changes rolled over into better transmission behavior. (And this was in the context of performance tuning, too.)

I think this jives with our speculation of when and how the problem was introduced. The initial 2.0T engines were paired with eTorque and are not having this problem. But once eTorque was taken away, the 2.0T engines without eTorque is when we started seeing the issue.

Much like updated performance settings in the PCM has made the transmission shift better, it would make sense that if there was a significant loss of power (no eTorque) and the PCM's settings weren't updated to match it, then it could cause the transmission to shift in less optimal ways. Like we're seeing.

Mind you, that's speculation, but it is consistent with that thread's new piece of information regarding performance tuning in the PCM affecting the actual behavior of the TCM.

I think I'm going to see if I can't get Jeep to take a bite at the issue. For all the people who have complained about "turbo lag", I'd hope that a cost-free resolution would be welcomed. (Acknowledging that aside from this particular tune, that a throttle controller also seems to do a fine job addressing the problem.)

Put the transmission in manual mode to feel the turbo lag... which there isn't much. Also should mention that boost threshold ≠ turbo lag.

Good points!

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