N55 rough start and idle

acoelho · 07-31-2024, 12:08 AM

anyone know what would cause start ups and idles to be this rough? mods - bms intake, catless dp, PR coils, charge pipe. no tune or mhd yet. also have a vavletronic malfunction code which could be part of the problem. anything helps. start up video

wheela · 07-31-2024, 01:04 PM

Not sure if this is your problem, but I don't think you want to run PR coils without adjusting dwell times in the tune - MHD has a flash time option you can select for this. Also, that BMS intake will mess with your MAF readings unless you adjust for it in the tune. If it was my car, I'd remove the BMS intake, and get MHD to flash the correct coil option (or go back to stock coils). And definately look into the valvetronic codes.

07-31-2024, 12:08 AM	#1
acoelho New Member 0 Rep 5 Posts Drives: 2011 bmw 335xi e90 Join Date: Jan 2024 Location: CT iTrader: (0)	N55 rough start and idle anyone know what would cause start ups and idles to be this rough? mods - bms intake, catless dp, PR coils, charge pipe. no tune or mhd yet. also have a vavletronic malfunction code which could be part of the problem. anything helps. start up video
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07-31-2024, 01:04 PM	#2
wheela Major 511 Rep 1,005 Posts Drives: 2015 BMW X1 35i M-sport Join Date: Mar 2021 Location: Twin Cities MN iTrader: (0) Garage List 2015 X1 35i M-Sport [0.00] 2025 X7 M60i [0.00]	Not sure if this is your problem, but I don't think you want to run PR coils without adjusting dwell times in the tune - MHD has a flash time option you can select for this. Also, that BMS intake will mess with your MAF readings unless you adjust for it in the tune. If it was my car, I'd remove the BMS intake, and get MHD to flash the correct coil option (or go back to stock coils). And definately look into the valvetronic codes.
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