[darkphantom]

So I was looking and found this on the DIY: exhaust mod

Someone mentioned they saw this on another forum.

Originally Posted by bimmerpath View Post
To those seeking to modify the flap in the exhaust - a warning. I had unplugged the wire harness behind the tail light panel to keep the flap open at all times. I performed this mod nearly a year ago. I had recently noticed a pulsing of the throttle at constant speed. The pulsing was getting progressively worse, to the point that I thought I was going to stall at some points. I took the car in, they ran all computer tests, couldn't find any faults, except for my disconnected harness mod. They didn't think that was a problem. They were stumped and began working with BMW engineers to find out what was causing the pulsing throttle. The cause- the disconnected harness was causing the computer to constantly calculate the correct parameters to compensate for the minor back pressure drops caused by the flap not closing (the flap should be closed at constant speed).

After all that, they loaded the new 30.0 software and cleared all adaptations.

As to the lag people are experiencing, it is my opinion that the drive-by-wire throttle adapts to peoples' driving habits and initially the throttle is not sure if you want full on gas, so it hesitates and then gives you the gas. Drive your car hard for a while and I think people will notice the responsiveness comes back - it has for me.

To all those who think the new software causes turbo lag, it would be nice if an engineer would chime in with their opinion. It would seem to me that turbo lag would be entirely mechanical and could not be effected by a software mod.

Is this really true??

[Brunotheboxer]

it must be because its on the internet.

[noro]

hmm interesting. The big question for the 1st post you noted is why did it take a year for that problem to arise? It sounds like in his case the cats or the O2 sensors where not damaged. I am finding hard to believe that the problem would not be immediate.

As for the 2nd post, the "THE DUAL PIPES ON THE 335 TAKE TURNS RELEASING EXHAUST FUMES" makes no sense. There is only one flap so how do they "TAKE TURNS".

And thirdly, I rarely find knowledgeable people finishing their argument with "TRUST ME I KNOW"

[quest556]

Doesn't sound plausible to me, otherwise all the folks that have reduced back pressure with modded exhausts would have experienced this long ago.

Sounds to me like the tech's made the unplugged harness the issue when they could find no other.

Did the flash fix the issue?

[darkphantom]

Originally Posted by noro

hmm interesting. The big question for the 1st post you noted is why did it take a year for that problem to arise? It sounds like in his case the cats or the O2 sensors where not damaged. I am finding hard to believe that the problem would not be immediate.

As for the 2nd post, the "THE DUAL PIPES ON THE 335 TAKE TURNS RELEASING EXHAUST FUMES" makes no sense. There is only one flap so how do they "TAKE TURNS".

And thirdly, I rarely find knowledgeable people finishing their argument with "TRUST ME I KNOW"

I dismissed the 2nd statement as it seemed to be posted by an idiot.

As for the problem being long term - these vehicles are not that old, but since the exhaust mod is a bit old - I'm wondering the same thing as to why someone else hasn't had this happen to them. hmm

It was just something I ran across and wanted to know if anyone knew anything about it