ATS-V throttle close: ONLY at part throttle

[jwbbuck]

I have the far-too-common throttle closing issues, but ONLY during part throttle. WOT throttle (and less than say 20%), car works great. But, anything between 30 and 90% accelerator position, the throttle opens / closes violently.

I have had 2 tuners work work on this car with no success.

Anyone have any thoughts on:

changes to sensors or parts?
layout files to 'see' what might be causing the car to command the throttle closing / opening

My car:
2017 ATS-V coupe
CAI
Catless DP
FlexFuel
stock cat-back
fuel cam upgrade
LPFP upgrade

throttle closing tuner 1 073021.PNG

[cadillactech]

I have the far-too-common throttle closing issues, but ONLY during part throttle. WOT throttle (and less than say 20%), car works great. But, anything between 30 and 90% accelerator position, the throttle opens / closes violently.

I have had 2 tuners work work on this car with no success.

Anyone have any thoughts on:

changes to sensors or parts?
layout files to 'see' what might be causing the car to command the throttle closing / opening

My car:
2017 ATS-V coupe
CAI
Catless DP
FlexFuel
stock cat-back
fuel cam upgrade
LPFP upgrade

throttle closing tuner 1 073021.PNG

Post your file.

Looks like a torque table issue just from glancing at it but the file would help

[jwbbuck]

Bickhart - current tune 071521.hpt

Thanks for taking a look.......

.hpt file attached.

[cadillactech]

If you look at your log and file, any time you have the throttle closing with a steady accelerator pedal position, your delivered/immediate engine torque is either equal or exceeding your max torque parameter. This is most likely the cause of your throttle closing. You are also having these two parameters pretty close to the peak torque parameter and that can also close the throttle and pull spark as well.

Max torque comes mostly from the virtual torque tables, which look like they have been modified a little but unsure of how much, they may need increasing in these areas that you are having the throttle closing.

I also see your driver demand torque request is lower than your actual axle torque/immediate axle torque at times. If the driver demand isn't high enough it can limit as the pedal is asking for a certain about of torque and your engine is making more than asked for so the throttle closes.

Looks like your are getting over 25PSI manifold pressure at 2000RPMs and more at 3000RPM, likely your peak torque tables need to be raised in the lower RPMs with such a high manifold pressure as well as the virtual torque tables from the extra manifold pressure.

You might start with raising driver demand in the pedal areas that are closing the throttle and seeing if that helps. Since it is one table it is simpler to test and see if the changes help. Try 5-10% changes

What did it put down on the dyno?

[jwbbuck]

Thanks for the simple yet detailed explanation. I am a rookie tuner.

It seems like I better start getting educated since I have 2 tuners that have both failed to get the throttle closing / opening straightened out. And, I might-as-well just glue the MPVI interface to the OBDII port!

I'll make some changes over the next few days and post my results.

Thanks again

[jwbbuck]

I think the manifold pressure numbers you are seeing are absolute pressure (Dsrd boost and Abs Boost). I used HiRes Boost for manifold pressure data and 'm seeing about 21psi (gauge pressure) max on 93 octane and 23psi on E50. I purchased this car used and have not dyno'd..... I was told it is 600whp on E50. 60-130mph is 7.8..... so 600whp might be close.

[cadillactech]

I think the manifold pressure numbers you are seeing are absolute pressure (Dsrd boost and Abs Boost). I used HiRes Boost for manifold pressure data and 'm seeing about 21psi (gauge pressure) max on 93 octane and 23psi on E50. I purchased this car used and have not dyno'd..... I was told it is 600whp on E50. 60-130mph is 7.8..... so 600whp might be close.

Yes they are absolute pressure. 25PSI absolute is about 11PSI boost pressure depending on your baro which is great for the low RPMs, they are spooling quick.

E50 is about the max you want to run on these cars with your fuel mods, depending on which company fuel cam you have. The fuel system needs some work to support more ethanol.

If you have a full throttle log with fuel pressure low and high side logging you can tell if you have maxxed out your fuel system.

[jwbbuck]

Between 2 professional tuners and my own tunes, I have made over 100 attempts at resolving the throttle closing issue without any improvement. Has anyone tried using a Cadillac dealer / mechanic to return the ECM (maybe TCM) back to stock using the GM tool? And then, retrurning to a modified tune using HPTuners? Im wondering if something that HPTuners doesnt touch is corrupt on my ECM. Is there a chance the TCM will become locked again? I have an '17 that was unlocked.

[cadillactech]

You should be able to reflash the calibration back to stock using HP Tuners if you have your original file. Not likely something is corrupted unless you are getting error codes or warning messages.

Were the virtual torque tables modified to take care of your throttle issues?

[jwbbuck]

Cadillactech,

I have modified VTT tables in 5-10% increments to 50% of the current settings from the tuner that built the car without any effect on the throttle closing. The other tuner uses locked tunes that I cannot see. I think he has focused on DD tables and he has gone all the way back to stock without any change in throttle closing.

Im wondering if a table that HPTuners doesn't touch is causing this problem.

[cadillactech]

Can you post a log and a file?