I was fiddling around with the X3 the other day and I set the shifts points +5mph. I took it for a test drive and stomped on it and the car would get up and go from 0-20mph, then level out(accelerate slowly) then once it hit around 40mph it would downshift and take off again. This was all under WOT.

I plug in the X3 and set the shift points to 0 and test drive it again. The problem goes away. Accelerates hard and nearly breaks lose from 1-2. Shift firmness is set to 25%(highest).

What would cause the car to accelerate hard 0-20mph,accelerate slowly 20-40mph, then downshift and accelerate hard again? WOT was maintained the whole time.

 

Probably a programming conflict with the ECU. Don't mess with the stock shift points, they're nearly perfect on a 99-04, it's the 96-98s that can use some tinkering.

 

Can you just adjust the shift firmness with an X3? Helped with my diablo.

 

Yeah the shift firmness is at 25% (highest setting).