N55 engine stall during accel

amesser325 · 11-06-2019, 08:22 AM

Hey guys - curious if anyone else has had this happen. Hard to narrow down a forum search for 'engine stall' and the dozen or so posts I read were not close to what happened to me.

Driving my 12 xDrive35i with the 8sp auto, I came up behind a car going about 5 mph under the speed limit so did a full throttle accel to pass. I believe I pulled my foot off the gas as the trans was shifting (so ~6500+ rpm). I had made the pass at this point so I was just going to coast back to the speed limit but I looked down and saw the tach read 0 rpm. The trans had moved itself to neutral so I was just coasting along. I tried to start but no joy. I wasn't sure if it's required to be in Park to start so I pulled off the road to come to a stop. Along the way a few errors popped up - DSC / 4x4 / etc. Got stopped and put it in neutral. When I went to start a plume of smoke came from under the hood, so I hurriedly opened to confirm no fire. Tired to start one more time, more smoke so I had it towed home.
I've spent the last few days going over things - pulled 3 plugs (all look good), visual inspection of piston tops - look "normal" (not wet from fuel, coolant, oil), inspection of all pipes from inlet filter to intake manifold inlet - all good. VC was recently replaced and I inspected for good measure.
After buttoning everything back together I tried to start. I could hear the starter make some noise but the engine didn't crank. Active code A0B4 - crank signal but no crank. Pulled the manifold and starter - it's definitely failed, so that will be replaced.

My question, however, is has anyone had a similar engine stall? My working theory is that when I lifted from basically 100%/kickdown to 0% throttle instantaneously timed with the trans shift, the engine control system was not able to respond quickly enough to the engine deceleration since there was no call for fueling. I'll get the new starter today and will crank to see but wondered if I was setting myself up for engine failure.

New battery ~ 6 months ago.

Thanks,

Andy
12 X5 35i
15 M235i
ex-07 530iT

X5 MAN · 11-06-2019, 12:18 PM

I am no mechanic but a friend had a similar cutoff during acceleration and he was told he had blown the turbo.

amesser325 · 11-06-2019, 09:43 PM

Thanks, after putting the new starter on and buttoning the engine back up I tried to crank again. No joy.
I put a breaker bar on the crank nose bolt and it seems to be seized. Unsure if rod or main but since the block is not ventilated I presume it spun a main for some reason. Obviously when at/near redline but not sure why that would be the case.

Fun times...

Andy

12 X5 35i

ClevelandBeemer · 11-27-2019, 08:18 AM

Did you replace your valve cover gasket or oil filter/oil cooler gasket recently?

11-06-2019, 08:22 AM	#1
amesser325 New Member 0 Rep 12 Posts Drives: 15 M235i Join Date: Sep 2018 Location: Bloomington, IN iTrader: (0)	N55 engine stall during accel Hey guys - curious if anyone else has had this happen. Hard to narrow down a forum search for 'engine stall' and the dozen or so posts I read were not close to what happened to me. Driving my 12 xDrive35i with the 8sp auto, I came up behind a car going about 5 mph under the speed limit so did a full throttle accel to pass. I believe I pulled my foot off the gas as the trans was shifting (so ~6500+ rpm). I had made the pass at this point so I was just going to coast back to the speed limit but I looked down and saw the tach read 0 rpm. The trans had moved itself to neutral so I was just coasting along. I tried to start but no joy. I wasn't sure if it's required to be in Park to start so I pulled off the road to come to a stop. Along the way a few errors popped up - DSC / 4x4 / etc. Got stopped and put it in neutral. When I went to start a plume of smoke came from under the hood, so I hurriedly opened to confirm no fire. Tired to start one more time, more smoke so I had it towed home. I've spent the last few days going over things - pulled 3 plugs (all look good), visual inspection of piston tops - look "normal" (not wet from fuel, coolant, oil), inspection of all pipes from inlet filter to intake manifold inlet - all good. VC was recently replaced and I inspected for good measure. After buttoning everything back together I tried to start. I could hear the starter make some noise but the engine didn't crank. Active code A0B4 - crank signal but no crank. Pulled the manifold and starter - it's definitely failed, so that will be replaced. My question, however, is has anyone had a similar engine stall? My working theory is that when I lifted from basically 100%/kickdown to 0% throttle instantaneously timed with the trans shift, the engine control system was not able to respond quickly enough to the engine deceleration since there was no call for fueling. I'll get the new starter today and will crank to see but wondered if I was setting myself up for engine failure. New battery ~ 6 months ago. Thanks, Andy 12 X5 35i 15 M235i ex-07 530iT Last edited by amesser325; 11-06-2019 at 08:31 AM.. Reason: added note on battery
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11-06-2019, 12:18 PM	#2
X5 MAN Lieutenant 78 Rep 491 Posts Drives: 2011X5 50iM-Sport;2016X3 35i M Join Date: Aug 2018 Location: USA iTrader: (0)	I am no mechanic but a friend had a similar cutoff during acceleration and he was told he had blown the turbo.
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11-06-2019, 09:43 PM	#3
amesser325 New Member 0 Rep 12 Posts Drives: 15 M235i Join Date: Sep 2018 Location: Bloomington, IN iTrader: (0)	Thanks, after putting the new starter on and buttoning the engine back up I tried to crank again. No joy. I put a breaker bar on the crank nose bolt and it seems to be seized. Unsure if rod or main but since the block is not ventilated I presume it spun a main for some reason. Obviously when at/near redline but not sure why that would be the case. Fun times... Andy 12 X5 35i
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11-27-2019, 08:18 AM	#4
ClevelandBeemer Second Lieutenant 94 Rep 262 Posts Drives: 2013 BMW 335i M-Sport Join Date: Jul 2014 Location: Cleveland, OH iTrader: (0) Garage List 2021 BMW X5 45e [0.00] 2013 335i [0.00] 2015 BMW S1000R [0.00]	Did you replace your valve cover gasket or oil filter/oil cooler gasket recently?
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