+6 Base Cal 1.5T CVT Subtle "surging" while under acceleration

[hifi]

Okay Spunkster,

I had it in me to perform one more run/program today, so here it is:

Ran the +3 base calibration for the first time. Used the "improved throttle response" and "improved turbo spool/response" options.

I ran a couple WOT's from stop and one from a rolling 30mph or so. That last one made me laugh as it broke the tires loose!
The "surging/jerking" under acceleration is still there, BUT! Very muted, so that is an improvement.
Without a doubt? This +3 Cal feels like it is more responsive and I didn't ever break the tires loose on the +6 while rolling, maybe slightly on takeoff.

So what that probably tells us is the engine isn't getting the right "mix" of something in terms of air or fuel, and this gets more pronounced as we attempt to increase boost.

Attached is the +3 datalog. I'm thinking (at least under the +6 datalog above) that you all should be able to see if it is AF, timing, CAM, fuel or something "blipping" as the ECU attempts to adjust.

*I am running these at a minimum of 10 mins under normal loads before recording these datalogs as well after reflash.

For now, the +3 made me smile...the +6 has been definitely falling flat under acceleration.

I think something was missed during model year changes here folks...if you can try and run a 2020 sport touring hatch model (the exhaust setup is just a bit different than the regular touring model, all of the sport models should have similar exhaust setup) I doubt that is what is driving this, but there is something the engine needs, and is just not getting here.

Thank you for the support! Please let me know if there is anything you see in the +6 I can tweak. The reason I think we should start there is because the issue is so much more pronounced, and if we fix it there? It will just lead to making the +3 perfect.

One other thing? I made DARN certain this was repeatable. This isn't some imperceptible issue, its repeatable and exactly the same with each test. I don't want to mess this up for myself or anyone else.

Ryan

[Spunkster]

Try disabling VSA in the calibration as well as with the button on the dash and see if either of those have an effect on this.

[hifi]

Try disabling VSA in the calibration as well as with the button on the dash and see if either of those have an effect on this.

Hey Spunkster,

So yes, that seems to have helped noticeably. Still some "transitioning" through the rpm range felt (maybe due to AF ratio/boost ratio tables) but way smoother. So, I would say you can definitely tout that as a solution/fix for this issue. It is night and day difference. I reflashed back, and the surging was there again.

Okay, that said, I had been disabling VSA manually before, so a few follow up questions for you:
1) What does the "disable VSA" option do in the tune that the button in the car does not?
2) Does the VSA become functional in the "ECO" button stock tune? (Would be nice to have the best of both worlds)
3) Is there a way to make the VSA disable permanent in the tune (so I don't have to continue to disable VSA with the button in the car every time I take off in addition to the disable option in the tune) the main reason is, since it won't accelerate smoothly without this fully disabled (at least for the CVT transmission variant)it would make sense to have it totally disabled or suffer with poor acceleration, in fact, it was slower 0-60 time in the datalog using +6 vs +3 because of the ECU intervention, which really defeats the entire purpose of the higher boost tune, now its responding as one would expect,I'm getting low 6's repeatably after the VSA "fix" versus well over 7's before which is closer to/if not worse than stock!

Thank you for the support!

Ryan

[d_butl3r]

___________car is going in and out of closed loop under WOT

- try toggling "Use AFM to determine WOT" Its under --->Calibration--->Closed loop
- log your AFM.c and notate where it is under WOT, then set the table data 50-100 less than what you logged. This will force open loop under WOT.
- also make sure your fuel trims are +/- 5 and your AF matches your AF command under WOT

[Spunkster]

Disabling VSA in software disables VSA, pressing the button turns off traction control

No there is no way to have VSA on when econ mode turns on

Currently there is no way to turn off both VSA and traction control via software

[hifi]

___________car is going in and out of closed loop under WOT

- try toggling "Use AFM to determine WOT" Its under --->Calibration--->Closed loop
- log your AFM.c and notate where it is under WOT, then set the table data 50-100 less than what you logged. This will force open loop under WOT.
- also make sure your fuel trims are +/- 5 and your AF matches your AF command under WOT

d_butl3r, thanks for the input/tips. Perhaps I'll play around a bit...the only issues I've read about with that recommendation though is really poor fuel economy...but perhaps that is only when you're "in it".

Cheers!

Ryan

[hifi]

Disabling VSA in software disables VSA, pressing the button turns off traction control

Thanks, makes sense...but interesting the button doesn't just do both anyways. I have read that using the button alone only disables part of VSA...so it must have always just been TC.

No there is no way to have VSA on when econ mode turns on

BUMMER

Currently there is no way to turn off both VSA and traction control via software

2XBUMMER

Appreciate the replies!

Ryan

[ddeatrich]

I have the same exact car as you. I've read through this entire thread and I have the same exact issue. You're the first person I've ever found to have this issue so I'm glad someone else does.

Did you ever make the problem go completely away? Was disabling VSA in calibrations what fixed it?

___________car is going in and out of closed loop under WOT

- try toggling "Use AFM to determine WOT" Its under --->Calibration--->Closed loop
- log your AFM.c and notate where it is under WOT, then set the table data 50-100 less than what you logged. This will force open loop under WOT.
- also make sure your fuel trims are +/- 5 and your AF matches your AF command under WOT

d_butl3r, thanks for the input/tips. Perhaps I'll play around a bit...the only issues I've read about with that recommendation though is really poor fuel economy...but perhaps that is only when you're "in it".

Cheers!

Ryan

[hifi]

Hello, yes by following the steps in this thread in terms of disabling VSA in the calibration and additionally (and unfortunately) manually using the button, it significantly reduces the surging issue. I can't say its 100%, but it is definitely noticeable. I believe it is present for others too. Throughout the years I've discovered that different individuals are more (hehem) shall we say more "in tune" with their vehicles and thus more sensitive to these details. Lets just say it was irritating and not so much after this fix. *remember to shut off your a/c too!

hifi