N55 FBO Stage 2 BM3 Hesitation and Loud Backfires

blakeblaeser · 04-13-2022, 07:26 AM

Hello all,

First time poster here!

Recently I've been experiencing a very odd issue that im hoping some of you have encountered before.

Upon cold startup, engine starts normally and has a slightly rough idle (usually this is normal for my car until it warms up a little). Putting the car into drive causes it to idle even rougher and the car is almost jumping forward with my foot on the brake. Once i start driving, the the car almost stutters and hesitates to shift, its very odd. I'll put my foot on the gas just a little bit and it jerks back and forth on acceleration. Then getting a little higher into RPMS and near the shift from 2nd to 3rd, the engine stutters badly. Almost sounds like its misfiring in that moment. Then once the car gets warm enough to backfire, in the low RPMS the backfires are VERY loud and sounds concerning. Ive had this setup for about a year and never heard a backfire like these ones. It only happens when the car isnt completely warmed up. Once the car is to temperature everything seems to be okay, no stutter, no hesitation on shifts, and no loud backfires. Im very confused as to what this could be because there are no trouble codes coming from the ECU. Any help would be much appreciated!

Thanks guys,

Blake

SoCalCarGuy · 04-13-2022, 09:48 AM

plugs most likely. or your oil is wrong weight

thejeremyman9 · 04-13-2022, 12:43 PM

mileage? mods (intake)? what happened before the problem started? we need context, you cant just describe a problem...

Flash back to stock and drive/rescan for codes, BM3 can suppress misfire codes.

04-13-2022, 07:26 AM	#1
blakeblaeser New Member 3 Rep 7 Posts Drives: 2018 340xi Stage 2 E30 Join Date: Apr 2022 Location: Milwaukee, WI iTrader: (0)	N55 FBO Stage 2 BM3 Hesitation and Loud Backfires Hello all, First time poster here! Recently I've been experiencing a very odd issue that im hoping some of you have encountered before. Upon cold startup, engine starts normally and has a slightly rough idle (usually this is normal for my car until it warms up a little). Putting the car into drive causes it to idle even rougher and the car is almost jumping forward with my foot on the brake. Once i start driving, the the car almost stutters and hesitates to shift, its very odd. I'll put my foot on the gas just a little bit and it jerks back and forth on acceleration. Then getting a little higher into RPMS and near the shift from 2nd to 3rd, the engine stutters badly. Almost sounds like its misfiring in that moment. Then once the car gets warm enough to backfire, in the low RPMS the backfires are VERY loud and sounds concerning. Ive had this setup for about a year and never heard a backfire like these ones. It only happens when the car isnt completely warmed up. Once the car is to temperature everything seems to be okay, no stutter, no hesitation on shifts, and no loud backfires. Im very confused as to what this could be because there are no trouble codes coming from the ECU. Any help would be much appreciated! Thanks guys, Blake
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04-13-2022, 09:48 AM	#2
SoCalCarGuy First Lieutenant 132 Rep 345 Posts Drives: 2019 440ix cpe + 2018 x4 m40i Join Date: Mar 2019 Location: LA, CA iTrader: (0)	plugs most likely. or your oil is wrong weight
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04-13-2022, 12:43 PM	#3
thejeremyman9 Major General 4374 Rep 7,622 Posts Drives: 2015 BMW 335i Join Date: May 2019 Location: Cali iTrader: (0)	mileage? mods (intake)? what happened before the problem started? we need context, you cant just describe a problem... Flash back to stock and drive/rescan for codes, BM3 can suppress misfire codes.
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