[mgeller]

Odd shifts on launch control. Going 1st-2nd-1st-2nd. This has happened a few times but only in sport+. Is this just traction control kicking in? The tires did chirp a small amount on launch, but I thought sport+ is supposed to have a higher threshold of the wheels breaking loose.

[thejeremyman9]

From my experience the car will always shift early on the 1-2 shift if there is any wheelspin in 1st gear. This happens in sport+ or DSC fully off. Its also impacted by your max RPM settings if you have a TCU flash. For example when i lowered my max rpm shiftpoint in XHP, the car would shift even earlier on the 1-2 shift if there was wheelspin. I have never had a 1-2-1, but i suppose if you spun badly with the kickdown depressed, the 1-2 happened early enough so that you were at low enough RPM in 2nd once you got traction that you had enough RPM to go back to 1st, it could happen.

What tires are you running and how bad did you spin 1st?

[mgeller]

Originally Posted by thejeremyman9

From my experience the car will always shift early on the 1-2 shift if there is any wheelspin in 1st gear. This happens in sport+ or DSC fully off. Its also impacted by your max RPM settings if you have a TCU flash. For example when i lowered my max rpm shiftpoint in XHP, the car would shift even earlier on the 1-2 shift if there was wheelspin. I have never had a 1-2-1, but i suppose if you spun badly with the kickdown depressed, the 1-2 happened early enough so that you were at low enough RPM in 2nd once you got traction that you had enough RPM to go back to 1st, it could happen.

What tires are you running and how bad did you spin 1st?

Hey, thanks for your input. It seemed very odd at first but now it's all making sense. It shifted early, then dropped to 1st again once traction caught. It seems to keep happening with launch control, so maybe I should just put that feature to bed and try other techniques.

I put on MPS4S about 2 months ago, so the tires should be good. Compared to the stock run flats, the spin didn't feel all that dramatic, but I guess I was wrong. I'll play with it some more and see if It was just a bad launch, poor surface, or a combination of.

[thejeremyman9]

Originally Posted by mgeller

Hey, thanks for your input. It seemed very odd at first but now it's all making sense. It shifted early, then dropped to 1st again once traction caught. It seems to keep happening with launch control, so maybe I should just put that feature to bed and try other techniques.

I put on MPS4S about 2 months ago, so the tires should be good. Compared to the stock run flats, the spin didn't feel all that dramatic, but I guess I was wrong. I'll play with it some more and see if It was just a bad launch, poor surface, or a combination of.

Yeah, that's normal then. Your rpm in 2nd was just too low once you got traction.

I run the same tires, 255/35/19 rear on OEM wheels. I am in a 335 not 340, but i am FBO + more mods, MHD stage 2+ E20 map, XHP stage 3, etc (stock turbo). If i am on a clean, dry road and its not extremely cold outside i can footbrake launch with little to no spin. I never use LC because of (1) drivetrain wear and tear and (2) as you experienced, you just spin more so its not even really faster, unless maybe you were on a prepped surface.

In terms of launching, the most success i have on the street is as follows: At a dead stop, apply light-med pressure on the brake with your left foot (no need to slam it like using LC). Then, quickly floor it with your right foot and let go of the brake about 0.5-1sec later as soon as RPMs rise. You are only using the brake to prevent the car from rolling while you stall the converter and start to spool the turbo, not to actually hold the car back. This preloads the drivetrain and gives you a little RPM/spool without the hard launch of LC that breaks traction.

Also, assuming your car is supported, you could get XHP and try things like launch in 2nd gear and using the LC custom editor.

[mgeller]

I'll give that method a shot; I appreciate the tips! I will flash XHP & other goodies once the warranty runs out later this year. Launching in 2nd sounds ideal. For now, MPPSK has kept a smile on my face, but I'm eager to go down the mod rabbit-hole, haha.