N51 sulev misfires

xezo · 02-27-2020, 05:42 AM

Hello,

I'm started getting weird misfires after driving it a bit harder. Codes are P0302 and P144B. P0302 code dissapears after shutting down the engine and starting it up, but P144B stays there. Misfire appears when you drive the car calmly for a longer time period and hitting the pedal to the floor. Could it be the coil plugs, because I checked spark plugs, they are fine.

CTinline-six · 02-27-2020, 08:10 AM

How many miles on the car? Mine is a 2009 N51 and I had one of my coils fail around 40,000 miles. I accelerated briskly onto an on-ramp and the light came on and the engine started shaking. Mine was a P0304 code (cylinder 4 misfire) but the problem followed the coil when I swapped it around. I replaced all the coils at once and did the plugs while I was there.

In theory 40,000 miles is pretty low for them to go out, but at that point the car was still 10 years old with plenty of heat cycles. I've read from a few different sources that the N51 is a bit harder on coils/plugs than the N52. I'm not sure about the validity of this, but I also owned a 2006 N52 that had original plugs and coils at 102k miles and they worked fine before I swapped out the plugs, so it might be true.

m_thompson · 02-28-2020, 07:13 AM

I had a coil fail at 55,000 miles and 10 years.

avocet · 02-28-2020, 07:41 AM

Although rare, plugs can fail and look perfectly fine. I would either swap plugs around to try and move the issue(I think P0302 is #2?) or replace them all. Then proceed to swapping coils if plugs don't move the problem.

Good luck!

xezo · 02-29-2020, 04:57 PM

Car has like 90k miles and I don't know if previous owner changed them. Also, it has LPG system installed.

Well the coil looked perfectly fine, swapped it to the other cylinder and the mistake followed it. Replaced only 1 coil for now, will be watching how engine runs right now. Thank you for the information.

02-27-2020, 05:42 AM	#1
xezo New Member 2 Rep 16 Posts Drives: E90 LCI 328xi N51 Join Date: Oct 2019 Location: Lithuania iTrader: (0)	N51 sulev misfires Hello, I'm started getting weird misfires after driving it a bit harder. Codes are P0302 and P144B. P0302 code dissapears after shutting down the engine and starting it up, but P144B stays there. Misfire appears when you drive the car calmly for a longer time period and hitting the pedal to the floor. Could it be the coil plugs, because I checked spark plugs, they are fine.
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02-27-2020, 08:10 AM	#2
CTinline-six Hoonigan 6879 Rep 3,000 Posts Drives: '09 328i, '98 Wrangler Join Date: Dec 2016 Location: Connecticut iTrader: (0) Garage List 2009 BMW 328i N51 [0.00]	How many miles on the car? Mine is a 2009 N51 and I had one of my coils fail around 40,000 miles. I accelerated briskly onto an on-ramp and the light came on and the engine started shaking. Mine was a P0304 code (cylinder 4 misfire) but the problem followed the coil when I swapped it around. I replaced all the coils at once and did the plugs while I was there. In theory 40,000 miles is pretty low for them to go out, but at that point the car was still 10 years old with plenty of heat cycles. I've read from a few different sources that the N51 is a bit harder on coils/plugs than the N52. I'm not sure about the validity of this, but I also owned a 2006 N52 that had original plugs and coils at 102k miles and they worked fine before I swapped out the plugs, so it might be true. __________________ "Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should." -Dr. Ian Malcolm, Jurassic Park
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02-28-2020, 07:13 AM	#3
m_thompson Major 133 Rep 1,416 Posts Drives: M-Sport 128i, 328xi, 3.0CS Join Date: Jun 2008 Location: New England, USA iTrader: (0) Garage List 2009 128i [0.00] 1972 3.0CS [10.00]	I had a coil fail at 55,000 miles and 10 years. __________________ '09 128i - Black Sapphire Metallic\Coral Red\Glacier Silver\N51 DISA\6MT\Navigation\Premium\M-Sport\Heated seats\Xenon\Headlights\iPod\Smartphone\Euro Delivery
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02-28-2020, 07:41 AM	#4
avocet Major 252 Rep 1,157 Posts Drives: 2007 328i 2011 X5d Join Date: Sep 2010 Location: Vancouver bc iTrader: (0)	Although rare, plugs can fail and look perfectly fine. I would either swap plugs around to try and move the issue(I think P0302 is #2?) or replace them all. Then proceed to swapping coils if plugs don't move the problem. Good luck!
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02-29-2020, 04:57 PM	#5
xezo New Member 2 Rep 16 Posts Drives: E90 LCI 328xi N51 Join Date: Oct 2019 Location: Lithuania iTrader: (0)	Car has like 90k miles and I don't know if previous owner changed them. Also, it has LPG system installed. Well the coil looked perfectly fine, swapped it to the other cylinder and the mistake followed it. Replaced only 1 coil for now, will be watching how engine runs right now. Thank you for the information.
	Appreciate 0 Quote