[craigss50]

Yesterday I did some 0-60 runs and after 2 successful runs 4.2 and 4.3 the car would fall flat and hesitate before launching. This happened 3 times in a row and the car had 30 minutes between the 2 successful runs and the additional 3 bogged down runs. It's a 2017 2 SS A8. I then tried a run without launch control and it did not bog. I ran a diagnostic from a OBD2 reader and no codes. Any ideas? Could the AFM cause this? Seems the it only does it when Launch control is used.

[Aragorn]

It’s probably the Nannie’s built in to protect the drive train. After market throttle body may help.

[Kerry]

I had the same thing when I first started using launch control. Seems like something is wrong but its killing timing to stop the spinning and completely normal. Its how it modulates the power. a log will show the timing going up and down.

[Spaceme1117]

I think it is normal. When I do launch control, you can tell it is pulling a lot of timing at first so that there is traction.

When I just hammer it from a stop, the car will spin, shift to 2nd, spin, shift to 3rd, spin and then get traction.

These LT1 engines are just plain beasts. Launch control is reigning in the beast for traction.

[craigss50]

Originally Posted by Kerry

I had the same thing when I first started using launch control. Seems like something is wrong but its killing timing to stop the spinning and completely normal. Its how it modulates the power. a log will show the timing going up and down.

Makes since specially sine the outside temperature dropped a couple degrees to 69 degrees when I did the second set of 0-60 runs. Guess the Michelin 4S tires got cold and couldn't hold her back enough.

[cmitchell17]

So for whatever reason GM really screwed up the launch control calibration, at least on the SS'es. This is normal and it pulls timing (and might even start to use predicted torque control (basically where it starts to use the throttle blade to control torque instead of pulling timing)).

The bad part about this is that the module that controls the traction and launch control, the chassis control module, has no aftermarket options that I know of to recalibrate it. So even with HP Tuners or EFILive or anything like that, there's nothing you can do to fix this.

Even with drag radials (Nitto NT555R2's), which can almost dead hook from a dead stop in the right temperatures and surface conditions, the launch control will still bog the same amount as it does with stock tires. It's like it completely ignores the wheel speed sensor feedback and just pulls the same amount of torque.

It's a real shame that we can't fix it, because I feel like with the launch control optimized it could be made to work very well for actual 1/4 mile runs and launches.

[cjperformance]

Not 100% sure it takes effect with launch control, but there is a minimum timing table that can be adjusted. If I recall, stock values allow negative timing during shifts and such. May be the same reduced power mode that affects launch control timing.

Of course adjusting that will affect other things too. But as others stated, theres nothing specific to launch control that can be tuned as far as i know.

[KingLT1]

It's torque management limiting throttle.

[craigss50]

Originally Posted by cmitchell17

So for whatever reason GM really screwed up the launch control calibration, at least on the SS'es. This is normal and it pulls timing (and might even start to use predicted torque control (basically where it starts to use the throttle blade to control torque instead of pulling timing)).

The bad part about this is that the module that controls the traction and launch control, the chassis control module, has no aftermarket options that I know of to recalibrate it. So even with HP Tuners or EFILive or anything like that, there's nothing you can do to fix this.

Even with drag radials (Nitto NT555R2's), which can almost dead hook from a dead stop in the right temperatures and surface conditions, the launch control will still bog the same amount as it does with stock tires. It's like it completely ignores the wheel speed sensor feedback and just pulls the same amount of torque.

It's a real shame that we can't fix it, because I feel like with the launch control optimized it could be made to work very well for actual 1/4 mile runs and launches.

That explains why I did not detect any wheel spin before it bogged down. Just no response then the system fed some throttle. I went from 4.2 when operating correctly to to 4.7 0-60. When it works it's awesome though.

[cmitchell17]

Originally Posted by cjperformance

Not 100% sure it takes effect with launch control, but there is a minimum timing table that can be adjusted. If I recall, stock values allow negative timing during shifts and such. May be the same reduced power mode that affects launch control timing.

Of course adjusting that will affect other things too. But as others stated, theres nothing specific to launch control that can be tuned as far as i know.

So you're right but I've never tried to lower there min timing table and test it out. My thing with doing that is you effectively kind of break other necessary torque management functions. I am weird in that I like those things to work so I don't really like doing this as work around, for example we don't have a way to partially reduce torque management during upshifts so the only way to do it partially is playing with the timing in this table.

My thinking is, but like I said haven't tested it, is that the launch control TM is done mostly with the throttle (predicted TM), although you can definately hear the timing being pulled in parallel. I think even though I think the stabilitrac system and brake control module sources its min timing in a different way. So basically I think even if you max this min table out, I think stability systems can still pull timing. So I haven't confirmed this but I know stabilitrac still seems to work correctly even if you increase the min table, but again I haven't looked at the logs in detail to confirm.

[FlukeSS]

Originally Posted by craigss50

Yesterday I did some 0-60 runs and after 2 successful runs 4.2 and 4.3 the car would fall flat and hesitate before launching. This happened 3 times in a row and the car had 30 minutes between the 2 successful runs and the additional 3 bogged down runs. It's a 2017 2 SS A8. I then tried a run without launch control and it did not bog. I ran a diagnostic from a OBD2 reader and no codes. Any ideas? Could the AFM cause this? Seems the it only does it when Launch control is used.

Nannies.

Traction Control + Stabilitrak

Switch to Track/Sport Mode then hit the TC button off 2 times in quick succession. This turns off TC and enables ESC Competitive mode.

Give it another try.

If it still bogs down which it shouldn't. Turn on Traction Control, then press and hold the Traction Control OFF Button for 10 seconds. This turns ALL nannies off.

[craigss50]

Originally Posted by FlukeSS

Nannies.

Traction Control + Stabilitrak

Switch to Track/Sport Mode then hit the TC button off 2 times in quick succession. This turns off TC and enables ESC Competitive mode.

Give it another try.

If it still bogs down which it shouldn't. Turn on Traction Control, then press and hold the Traction Control OFF Button for 10 seconds. This turns ALL nannies off.

Your first suggestion is how I do it but next time I will try holding down the TC button for 10 secs and see if that works.

[FlukeSS]

Originally Posted by craigss50

Your first suggestion is how I do it but next time I will try holding down the TC button for 10 secs and see if that works.

Hope that works for you. I had the engine bog down issue when I had my stock 275's when I switched to 305's the first method I gave you works np for me with no bog downs.

The Bog down might be part of the Launch Control System as well. I usually brake torque my tires to certain RPM's and never really had an issue with engine bog downs.

[Nilly Welson]

Originally Posted by craigss50

Yesterday I did some 0-60 runs and after 2 successful runs 4.2 and 4.3 the car would fall flat and hesitate before launching. This happened 3 times in a row and the car had 30 minutes between the 2 successful runs and the additional 3 bogged down runs. It's a 2017 2 SS A8. I then tried a run without launch control and it did not bog. I ran a diagnostic from a OBD2 reader and no codes. Any ideas? Could the AFM cause this? Seems the it only does it when Launch control is used.

It bogs down when your rear wheels start to lose traction. Its modulating your throttle to eliminate the wheel spin.