Possible Source from fueling cuts? (read on e90 post)

[a4dc89]

http://www.e90post.com/forums/showthread.php?t=192246

Looks like the bimmers are also experiencing fuel cuts perhaps this could be part of the whole fuel cut issue we b7s seem to have when chipped and test piped.

"Here, you can see a very big and prolonged dip between 5000-6000RPM. During this time, actual throttle drops down to approx 50%. This means that despite the pedal being floored to the carpet, the throttle is only half open. Kind of stinks, doesn't it? Not only does this throttle closure make the car feel "choked" and inconsistent, it's also more stressful on the turbos because they now have to push through a large intake restriction (the half closed throttle butterfly). This closure also defeats the purpose of adding free flow mods to your car in the first place. So why is the ECU inducing this nonsense? Well, it has to do with all those mods on the car. Each upgrade improves the volumetric efficiency (breathing) of the engine. Which then, in turn, results in:
-more boost (at the same wastegate DC)
-more torque (at the same boost pressure)
-more fuel consumption (at the same boot pressure)
So the ECU recognizes this implausibility/discrepancy and intervenes by closing the throttle."

This was posted there by the king of bmw 335 tuning, shiv

[RedS-line]

interesting. goes to show that no matter how far you WANT to push your engine, the ecu will always stand in your way.

[a4dc89]

I figured some of the tuners might want to chime in on this considering it was fixed with programming on the 335 by a programmer and the fuel cut problem with our cars even plagues some people who upgrade their pumps. Anyone?

[Nico]

The fuel cut on our cars is a hardware problem not a software problem. However the people with the more aggressive tunes are the ones that get the symptoms first, e.g APR stage 2 and Agressive Revo tunes.

There are several hardware problems that lead to fuel cut:
Worn cam lobes,
Damaged cam followers
Faulty Low pressure fuel sensor - thrust sensor
Faulty fuel pumps

The other problems with the PCV system also effects our engines.

The other thing to note is that the last time I checked the BMW tuners are still using chips to trick the ECU the car is behaving normally rather than what tuners are doing for our cars, where they actually reprogram the ECU. I guess the BMW tuners haven't thought of all the possible implications of modifying the ECU and missed a few things.

[KarimS3]

335i uses speed density vs MAF setup in our cars. Completely diff

[Mike@APR]

I can assure you all that premature throttle closure has NOTHING to do with the fuel cut in the FSI cars.

I have recorded fuel cuts with our proprietary ECU monitoring software (internal use only) and the throttle plate was 100% until AFTER the fuel issue had already occured. Once the fuel issue has happened, the ECU drops the N75 duty cycle through the floor and limits load (think boost) to send you into limp mode.