Quote:
Originally Posted by evilrho
I don't have MHD, and haven't done much research on it. Only thing non-stock about the car is the Dinan stage 2 software. I'm not convinced this is not a source of the A/C on lurching/hesitation issue, but folks have suggested it isn't.
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The “lurching” problem is a result of the idle being inconsistent with the a/c on, when the compressor cycles on/off the idle surges a little. On a DCT car (specifically the 135) the transmission keeps the clutches slightly engaged at a stop to sort of mimic a typical torque converter transmission, and when the idle surges it causes the car to lurch if your foot isn’t firmly on the brake. (I’m guessing this is what your talking about). Bmw came out with a software update/adaptation reset procedure to “fix” the problem but it just lessened it.
Dinan and MHD are both engine tuning software, XHP tunes the transmission. With the XHP software and “creep” turned off the clutches stay completely disengaged when the car is at a stop as long as the gas pedal isn’t pressed sort of like a manual transmission, this is how the M-cars are from the factory. This way if the engine surges or anything while your stopped at a light it’s not going to make the car lurch or hesitate or anything.