Heavy Misfires Under Slight Accelration (N54, 135i)

slamster · 05-29-2020, 03:40 PM

Hey all, just took some data:

https://datazap.me/u/slamster/wot-af...ata=3-14-15-20

Actually pulled pretty good! Still misfire on cylinder 6 however. I reset all adaptations.

stewbets · 06-02-2020, 02:57 PM

Looks like something is up with bank 1. Your AFR goes way lean in third gear and the trims don't try to compensate for some reason. And then when you let off throttle and coast, bank 2 goes to 234.95 as expected, but bank 1 is all over the place. I have no idea why your trims wouldn't add fuel to bank 1 when it's going lean during a pull.

mikeseli · 06-03-2020, 02:26 PM

Remove the engine cover and swap the two O2 sensor connectors and start her up again.

slamster · 06-05-2020, 12:54 PM

I did notice that the O2 sensor for bank 2 seems to drop out intermittently. Perhaps that is the issue. I can try the swap but won't that just default the computer to run in closed loop?

Knerr · 06-07-2020, 05:35 PM

Any updates? figure out what's going on yet?

Also, any specific reason you're not using full throttle in that log?

80% throttle isn't such a great way for us to see exactly what the DME is thinking.. also, instead of starting the log in 1st gear, start in 3rd gear at about 3k RPM or less.. full throttle, hold to redline or as long as you can stand it if its misfiring too badly.

gbm30 · 06-08-2020, 12:17 AM

When I had this issue, I had to make sure my plugs was gap correctly. Use one step colder plugs also. Solve all my issues

slamster · 06-08-2020, 01:48 PM

No solution yet.

That actually was full pedal.

It typically doesn't misfire when at high RPMs. They are down lower like 1-3k rpm.

I just replaced my sparkplugs - I don't that is the issue

BM3Rrrr · 06-09-2020, 11:55 PM

Yep need to do a 3rd gear log and only in 3rd. You did let off the pedal at 5200RPM in 3rd. Did you throw any codes after this pull? There is something going on here with fueling for sure. Your rail pressure is all over the place as well as AFR's and STFT's. Bank 1 not going to fuel cut off (234) on deceleration is usually leaking injectors

slamster · 06-10-2020, 02:20 PM

I just got a misfire on cylinder 6. That was the only code from the pull

I have gotten these on some cold starts:
- DME active codes -
2A7C - DME: Variable camshaft timing control, intake, cold start.
3100 - DME: Boost-pressure control, deactivation.

slamster · 07-10-2020, 05:54 PM

Hey all, just did the 3rd gear pull. Looks like the LPFP is dipping lower than 70 psi. I think the lowest was 58 psi

Here is the data: https://datazap.me/u/slamster/3rd-ge...l?log=0&data=9

Any other ideas before I bet a fuel pump? Just for some context, I replaced both my HPFP and LPF sensor.

slamster · 07-10-2020, 05:57 PM

I guess to further corroborate that theory that the low pressure is making cylinder misfire is the location of cylinder 6. Cylinder 6 is the last one on the fuel rail so if there was low pressure and and head loss through the rail the last cylinder would likely be the one to start misfiring first.

Sound reasonable?

BM3Rrrr · 07-12-2020, 07:09 PM

Quote:

Originally Posted by slamster

I guess to further corroborate that theory that the low pressure is making cylinder misfire is the location of cylinder 6. Cylinder 6 is the last one on the fuel rail so if there was low pressure and and head loss through the rail the last cylinder would likely be the one to start misfiring first.

Sound reasonable?

That log tells nothing really, only shows you going to 2600rpm......

Soden82 · 07-13-2020, 12:06 AM

Quote:

Originally Posted by slamster

Hey all, just did the 3rd gear pull. Looks like the LPFP is dipping lower than 70 psi. I think the lowest was 58 psi

Here is the data: https://datazap.me/u/slamster/3rd-ge...g=0&data=9

Any other ideas before I bet a fuel pump? Just for some context, I replaced both my HPFP and LPF sensor.

As far as I know anything above 50psi during a full is fine for the LPFP. Your logic seems correct with cylinder 6 being farther away on the fuel rail.

How is your rail pressure?

slamster · 07-31-2020, 02:50 PM

The rail pressure all over the place. You can see in the plot as well. It varies from ~600psi-2063psi

I just swapped both the HPFP and the LPFP sensor so it isn't an issue with either of those. If it is a fuel issue it would be a LPFP or filter

slamster · 08-24-2020, 10:49 PM

Alright everyone, I fixed it!

I just wanted to follow up with everyone on what the issue was because I hate when people don't follow up on the forums.

This one is especially embarrasing... I decided to swap the injectors on cylinder 5 and 6. When I pulled out injector 6 it had almost no resistance when pulled.

I think that it didn't seat properly or the clamp wasn't fully engaged on that injector. I take some comfort in the fact it is the hardest to see and get proper placement on.

Anyway, thank you all for the help along the way. I guess we all pay stupid tax...

05-29-2020, 03:40 PM	#45
slamster Enlisted Member 4 Rep 32 Posts Drives: 2009 135i Coupe Join Date: Mar 2017 Location: MN, USA iTrader: (0)	Hey all, just took some data: https://datazap.me/u/slamster/wot-af...ata=3-14-15-20 Actually pulled pretty good! Still misfire on cylinder 6 however. I reset all adaptations.
	Appreciate 1 335ilover507013.50 Quote

06-02-2020, 02:57 PM	#46
stewbets Captain 452 Rep 823 Posts Drives: '08 335xi, '04 545i Join Date: Sep 2019 Location: Dayton, OH iTrader: (0)	Looks like something is up with bank 1. Your AFR goes way lean in third gear and the trims don't try to compensate for some reason. And then when you let off throttle and coast, bank 2 goes to 234.95 as expected, but bank 1 is all over the place. I have no idea why your trims wouldn't add fuel to bank 1 when it's going lean during a pull.
	Appreciate 0 Quote

06-03-2020, 02:26 PM	#47
mikeseli Private 21 Rep 81 Posts Drives: 2009 335i Join Date: Apr 2014 Location: Montreal, QC or Massena, NY iTrader: (0)	Remove the engine cover and swap the two O2 sensor connectors and start her up again.
	Appreciate 0 Quote

06-05-2020, 12:54 PM	#48
slamster Enlisted Member 4 Rep 32 Posts Drives: 2009 135i Coupe Join Date: Mar 2017 Location: MN, USA iTrader: (0)	I did notice that the O2 sensor for bank 2 seems to drop out intermittently. Perhaps that is the issue. I can try the swap but won't that just default the computer to run in closed loop?
	Appreciate 0 Quote

06-07-2020, 05:35 PM	#49
Knerr I Have A Condition 111 Rep 118 Posts Drives: 2007 6MT 335i upgraded twins Join Date: Oct 2019 Location: Craiova, Romania iTrader: (0)	Any updates? figure out what's going on yet? Also, any specific reason you're not using full throttle in that log? 80% throttle isn't such a great way for us to see exactly what the DME is thinking.. also, instead of starting the log in 1st gear, start in 3rd gear at about 3k RPM or less.. full throttle, hold to redline or as long as you can stand it if its misfiring too badly.
	Appreciate 0 Quote

06-08-2020, 12:17 AM	#50
gbm30 Private 24 Rep 76 Posts Drives: bmw e90 330i Join Date: May 2013 Location: new york iTrader: (0)	When I had this issue, I had to make sure my plugs was gap correctly. Use one step colder plugs also. Solve all my issues
	Appreciate 0 Quote

06-08-2020, 01:48 PM	#51
slamster Enlisted Member 4 Rep 32 Posts Drives: 2009 135i Coupe Join Date: Mar 2017 Location: MN, USA iTrader: (0)	No solution yet. That actually was full pedal. It typically doesn't misfire when at high RPMs. They are down lower like 1-3k rpm. I just replaced my sparkplugs - I don't that is the issue
	Appreciate 0 Quote

06-09-2020, 11:55 PM	#52
BM3Rrrr Davy Jones, Giant Squid 272 Rep 913 Posts Drives: a Pirate Ship Join Date: Jun 2015 Location: The Isle of Tortuga iTrader: (0)	Yep need to do a 3rd gear log and only in 3rd. You did let off the pedal at 5200RPM in 3rd. Did you throw any codes after this pull? There is something going on here with fueling for sure. Your rail pressure is all over the place as well as AFR's and STFT's. Bank 1 not going to fuel cut off (234) on deceleration is usually leaking injectors __________________ 2010 e90 335i LCI - xHP - Mishimoto - BMS - CPe - Turbosmart - MHD - Eibach - Koni - VMR - LUX Last edited by BM3Rrrr; 06-10-2020 at 07:32 PM..
	Appreciate 0 Quote

06-10-2020, 02:20 PM	#53
slamster Enlisted Member 4 Rep 32 Posts Drives: 2009 135i Coupe Join Date: Mar 2017 Location: MN, USA iTrader: (0)	I just got a misfire on cylinder 6. That was the only code from the pull I have gotten these on some cold starts: - DME active codes - 2A7C - DME: Variable camshaft timing control, intake, cold start. 3100 - DME: Boost-pressure control, deactivation.
	Appreciate 0 Quote

07-10-2020, 05:54 PM	#54
slamster Enlisted Member 4 Rep 32 Posts Drives: 2009 135i Coupe Join Date: Mar 2017 Location: MN, USA iTrader: (0)	Hey all, just did the 3rd gear pull. Looks like the LPFP is dipping lower than 70 psi. I think the lowest was 58 psi Here is the data: https://datazap.me/u/slamster/3rd-ge...l?log=0&data=9 Any other ideas before I bet a fuel pump? Just for some context, I replaced both my HPFP and LPF sensor.
	Appreciate 0 Quote

07-10-2020, 05:57 PM	#55
slamster Enlisted Member 4 Rep 32 Posts Drives: 2009 135i Coupe Join Date: Mar 2017 Location: MN, USA iTrader: (0)	I guess to further corroborate that theory that the low pressure is making cylinder misfire is the location of cylinder 6. Cylinder 6 is the last one on the fuel rail so if there was low pressure and and head loss through the rail the last cylinder would likely be the one to start misfiring first. Sound reasonable?
	Appreciate 0 Quote

07-31-2020, 02:50 PM	#58
slamster Enlisted Member 4 Rep 32 Posts Drives: 2009 135i Coupe Join Date: Mar 2017 Location: MN, USA iTrader: (0)	The rail pressure all over the place. You can see in the plot as well. It varies from ~600psi-2063psi I just swapped both the HPFP and the LPFP sensor so it isn't an issue with either of those. If it is a fuel issue it would be a LPFP or filter
	Appreciate 0 Quote

08-24-2020, 10:49 PM	#59
slamster Enlisted Member 4 Rep 32 Posts Drives: 2009 135i Coupe Join Date: Mar 2017 Location: MN, USA iTrader: (0)	Alright everyone, I fixed it! I just wanted to follow up with everyone on what the issue was because I hate when people don't follow up on the forums. This one is especially embarrasing... I decided to swap the injectors on cylinder 5 and 6. When I pulled out injector 6 it had almost no resistance when pulled. I think that it didn't seat properly or the clamp wasn't fully engaged on that injector. I take some comfort in the fact it is the hardest to see and get proper placement on. Anyway, thank you all for the help along the way. I guess we all pay stupid tax...
	Appreciate 0 Quote