GXP Automatics with GMPP Tune...

ExtraCrispy · 07-20-2009, 10:12 AM

I have a 2007 GXP Auto with the GMPP tune. I have noticed that under aggressive driving that sometimes when you floor the gas pedal and the transmission calls for an upshift, the rpms on the engine climb past the normal rev limiter (up to 8000 befor I let off) and the shift never happens untill you let off the gas. Then it shifts and everything is normal. I have had this happen mainly when I'm coasting into a turn and then matt the gas to accelerate out of the turn.

Anyone else have this happen with the GMPP Tune???

P.S. I never noticed this before the tune so I don't think there is any actuall problem with the automatic except for the software itself.

Tom

Simkow · 07-20-2009, 11:11 AM

I've never experienced this. With the dashdaq I haven't even been able to get mine to hit 6400 RPMs; it always hits 63 something before shifting.

Tabletops · 07-20-2009, 01:11 PM

me either.

ExtraCrispy · 07-20-2009, 01:48 PM

If you guys or anyone else for that matter, have a chance to experiment to see if this happens I would appreciate it. I'm not going to the dealer for this- they would never duplicate the problem and it's not that big a deal anyway.

Thanks.
Tom

I1ULUZ · 07-20-2009, 02:30 PM

Highest I've seen on my DH isn't even 6200.

Only thing comes to mind is the engine was completely unload at WOT. So it's an internal problem with the trans. Maybe time to change the trans fluid. I've been told by a BMW tech these trans do not like heat.

typhoon · 07-20-2009, 02:48 PM

WOW! At 8000 rpm I would think you are seriously over revving the motor. There should be a rev limiter that kicks in even if your tranny is shot. My manual shift car won't rev over 6500 or so no matter what you do to it.

Mac · 07-20-2009, 03:35 PM

well ours is a 08 but an auto and have never seen this. Have done some hard shifting to it too. Well as hard as the nany controls will let. but at 8k rpm what kind of boost spikes are you seeing? i would think that you would get a code at that rpm(lein, over spin, something?

LatinVenom · 07-20-2009, 05:02 PM

He could have a bad tac.

ExtraCrispy · 07-20-2009, 10:43 PM

No my Tack is fine. It might not have hit 8K but it was definitely exceeding 7K. It's like the electronics call for a shift but the tranny doesn't and the engine revs right through the shift point until power is reduced and then it shifts. I'm not sure why the rev limiter doesn't work. It's only on high rpm up shifts. I only use "D" and I'm not ragging on the car. Just spirited driving.

Tom

ExtraCrispy · 07-20-2009, 10:47 PM

Max boost I have ever seen on the dic is 21. It usually stays at 19 with a blip of 20 now and then. I don't know what the boost is when it revs through the limiter as it happens to fast.

Tom