[335MHI]

Car hesitates/surges under medium ~ wide open acceleration, multiple attemps to fix have failed.

2008 335i sedan

Car ran perfect post: Active Autowerke Software and Race FMIC, Intake, downpipes, N55 coil packs, OEM replacement spark plugs, walnut blast @ dealership, new turbos @ dealership. (Fuel pump and injectors are the latest rev as well)

A few weeks after the new turbo install, a heavy hesitation / power surge developed. I could feel it and hear the boost pressure wavering. I found a boost leak on one of the intercooler 90 degree hose clamp locations and fixed it. It felt a little better but not much. I changed the diverter valves to Turbo Smart dual ports, and this seemed to minimize boost deviation, but the hesitation/surging issue remains. I pulled the spark plugs and noticed black residue in the threads and under the plugs. Picture attached.

Any help or suggestions are appreciated.

[enrita]

no picture. N55 coilpacks???
maybe its running too rich.
Codes?

[335gtl]

Hi! I had the same issue... Dealer fixed it by re-encoding the car modules and cat module after checking if DME software was the most recent. Never understood what they really did but apparently its common fix according to the BMW ing. when BMW can't find any mecanical issue.

[335MHI]

Yea the N55 packs are more robust (or so I was told). I was blowing coil packs frequently right after getting software, havent had an issue since I changed.

Not throwing any codes...

Pic Attached this time.

[enrita]

sorry but i havent heard of anybody having issues with stock coil packs even on very high power applications so you better go back to the OEM ones since your issue might be related to something NOBODY is using and maybe as well the tune you are running....