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      06-02-2012, 11:13 AM   #24
Surly73
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Canada
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Drives: 2007 E90 328i 6MT sport/prem
Join Date: May 2012
Location: Oakville, Ontario

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Well now I'm not sure which thread to post this in, but I noticed something interesting just this morning concerning my sudden lurch forward when slowly releasing the throttle.

1/ If the throttle isn't pressed past a certain point (something like 50%) for more than a second there is no lurch on release. If I'm giving it a little squeeze for a corner exit or something it can be completely smooth without the lurch when lifting.

2/ I did a squirt of WOT in one of the lower gear and was slowly lifting the pedal back towards 50% and partway through the pedal release it suddenly lurched to a lower amount of acceleration. This is the first time I've ever really been able to isolate the event and observe before and after. Usually I'm in the process of shifting when it does it. Pedal near WOT -> hard acceleration -> slowly releasing pedal -> slightly less acceleration -> sudden lurch to gentle acceleration at around 60% on the pedal, gentle acceleration effect continues and continues to reduce as I continue to smoothly release pedal.

I'm not sure where I should be going with this. Still don't have a K+DCAN cable to start looking for codes or clear all adaptations that a battery pull may not have done. Pedal module issue? Valvetronic issue? As far as I know the pedal module is a digital bus device and I can't just measure it with an ohmmeter to see that the values change smoothly on application and release.

Again, I'll reiterate that I'm being smooth with the controls and this happens at speed, not just first gear where driveline lurch is most evident. It'll still clearly do it in 4th. This is definitely something with the throttle operation like it's snapping Valvetronic "closed" suddenly when it was still accelerating briskly.

I still haven't been able to tear into the pedal module looking for aftermarket throttle remappers from previous owner(s). Unfortunately there's a lot of personal stuff keeping me tied up.