Just last wednesday on my drive home I took a 90deg corner and opened it up and got a weird popping sound (under WOT) and the car kindof bucked like it was going to stall. So I backed off and then just to test it, I floored it again and all seemed to be well. However every once in a while it would still do the same thing and I started to find out what conditions seemed to make it act this way.

From my observations, it seems to happen most at about 2-3k RPMs under wide open throttle. If I am easy on the throttle I do not seem to have the problem. It seems really picky in 5th gear. Today I held it for about 2-3 seconds in 5th while it was bucking and the service engine soon light came on :evil:

Some background info on my car. I have just over 5000 miles on it, changed the oil and filter at ~4700 miles. It is an S and all of this happens while in-gear so it has nothing to do with shifting.
15% reduction pulley
8.5mm magnecore wires
(and painted brake calipers )

The pulley was done a while ago (at helix)
Everything else was done by me. BMW 5w30 mobil 1 synthetic oil was used as well as a MINI oil filter

Also I don't know if it matters but it has been extremely wet this past week and if things change whenever it dries I will post more info.

Any ideas before I bring it to the dealer?

 

No ideas, except don't mention the pulley mod to your dealer ...

 

Went to Helix dyno day (For the fun drive and cheesesteaks... no dyno) and got Andy to hook it up to his computer and the fault was a misfire. Some consensus is to try new software so hopefully that will do it.

 

^ ^ THINK TWICE before you go for that software upgrade! See the many recent threads on CD 33 (the latest software) and the 2K-3K rpm stumble/lurch/yo-yo/etc. The consensus is that on an MCS, the software upgrade will actually make things WORSE than they now are.

Hopefully BMW will fix this software problem and issue a revision (CD 34), but until then, beware!

 

you know, I will get a similiar response out of my MC when excellerating through corners if the DSC is on...maybe try turning it off and see if that corrects the problem you are having

 

DSC is off... it usually is. It's a misfire in the engine. First I will probably try and pull the plugs and ensure the gap is set correctly (anyone know what it should be?) and maybe clean it off. If that doesn't do anything I will probably go for the software update because it's really obnoxious.