Datalog E92 335i Cylinder One Misfire & Lambda AFR, Help!

ClaytonT

New Member
Jan 25, 2021
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Hi Guys!

I’m new to the forums and a first time poster. Im hoping to get a bit of advice on a problem I’ve ran into as beside trawling YouTube tutorials and scrolling on forums I’m fairly inexperienced with the tuning of these vehicles.

Essentially I have had a 29CD code (Cylinder 1 combustion misfire) start popping up over the last few days. Spark plugs were replaced less than 5000km ago and coils checked at the same time. I had the same issue when I first purchased the car (it was and still is, running a third party stage one tune) and changing the spark plugs fixed it so am I right in assuming that now a coil has gone bad? Or do you guys recommend I go to one step colder plugs?

I’ve attached the log of the pull which caused the misfire, hopefully I’ve got the BBCode right lol. Is there any chance someone could take a look at the log and let me know their thoughts? I’m also curious about the Lambda AFR numbers and why it seems to have gone off the charts.

Thank you very much !
Clayton

Misfire Log

 
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RuskiRacer

Sergeant
Jul 17, 2019
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2009 e93 335i
Your pulling like 3 degrees of timing in cylinder 1. And your afrs are way off from each other. What mods are done to the car? What fuel?
 

ClaytonT

New Member
Jan 25, 2021
8
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Your pulling like 3 degrees of timing in cylinder 1. And your afrs are way off from each other. What mods are done to the car? What fuel?

yeah it’s not good, it’s on 98 octane and is FBO with VRSF Catless Downpipes, VRSF 7.5inch FMIC, VRSF Intakes and Aluminium Chargepipe, Factory Oil Cooler
 

RuskiRacer

Sergeant
Jul 17, 2019
429
157
0
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2009 e93 335i
Have you tried resetting 02 sensor adaptations? If that doesn't do anything you may just want to get new 02 sensors. And 1 step or 2 step colder plugs won't hurt either. You can fry the 02 sensors by doing to many pulls on them when they lean out like that
 

RuskiRacer

Sergeant
Jul 17, 2019
429
157
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2009 e93 335i
You have good fuel pressure, but by the end of the pull you can start to see the afrs really start to very from each other. What index injectors are on the car?
Screenshot_20210125-200738_Firefox.jpg
 

ClaytonT

New Member
Jan 25, 2021
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You have good fuel pressure, but by the end of the pull you can start to see the afrs really start to very from each other. What index injectors are on the car?
View attachment 48600
Interesting! I assume the injectors are stock, there’s no details on them in the mod list I got from the previous owner (I’ve only owned the car for four months). Could you please tell me how to reset the 02 adaptations? Is it through MHD?
 

RuskiRacer

Sergeant
Jul 17, 2019
429
157
0
Ride
2009 e93 335i
Yes you can reset them through mhd. Bmw had 12 revisions of injectors for the n54. Some of them were more problems than others and there really prone to carbon buildup. How many miles on the car?
 
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ClaytonT

New Member
Jan 25, 2021
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Yes you can reset them through mhd. Bmw had 12 revisions of injectors for the n54. Some of them were more problems than others and there really prone to carbon buildup. How many miles on the car?

Ah interesting, I’ll pull the cover off and have a look to see which index they are. It is an ‘07 so as early as it gets for the e92 I suppose, car has 90,000 miles on it
 

RuskiRacer

Sergeant
Jul 17, 2019
429
157
0
Ride
2009 e93 335i
Putting a catch can on the car if it doesn't have one already would be a good idea as well. I'd reset adaptations and go from there. 02 sensors aren't to expensive which is most likely the case since your short term fuel trims look ok. You could let the car sit over night and pull the plugs tommorow and smell if there's any fuel on them. If the coilpacks are original you may want to get some fresh ones. Delphi or eldors are usually my go to. You can get them on fcp euro with there lifetime warranty.
 

ClaytonT

New Member
Jan 25, 2021
8
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Putting a catch can on the car if it doesn't have one already would be a good idea as well. I'd reset adaptations and go from there. 02 sensors aren't to expensive which is most likely the case since your short term fuel trims look ok. You could let the car sit over night and pull the plugs tommorow and smell if there's any fuel on them. If the coilpacks are original you may want to get some fresh ones. Delphi or eldors are usually my go to. You can get them on fcp euro with there lifetime warranty.

Thanks man, it does actually have a catch can I forgot to mention that since it was installed on the car years ago. Alright cool I’ll give that a try. Probably a good idea to grab coil packs since I really should’ve done em with the plugs but thank you very much! I’ll give an update when I get some more info
 
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JohnDaviz

Sergeant
Jan 6, 2019
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335i E92 DCT
You should log Fuel Mod and probably RPM..

Your STFTs are flatlining. Thus your absurdly high AFRs.
 

ClaytonT

New Member
Jan 25, 2021
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You should log Fuel Mod and probably RPM..

Your STFTs are flatlining. Thus your absurdly high AFRs.
Alright thanks I will. Had a thought, if a bad coil is indeed causing a misfire on cyl 1, could the dme be detecting this and cutting fuel to that cylinder thus leaning the bank one mixture out and flatlining the STFT?
 

JohnDaviz

Sergeant
Jan 6, 2019
355
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335i E92 DCT
yes. If Misfire detected, STFTs for both banks flatline. At least it was the same on my car.
 

ClaytonT

New Member
Jan 25, 2021
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yes. If Misfire detected, STFTs for both banks flatline. At least it was the same on my car.
Interesting, definitely gonna switch these coils around tomorrow and fingers crossed that solves it - if I add any more logs I’ll make sure to monitor RPM and Fuel Mode. Would you mind telling me what Fuel Mode monitors/means
 

JohnDaviz

Sergeant
Jan 6, 2019
355
201
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335i E92 DCT
Logging the Fuel Mode should just confirm that the car is going into limp mode during the event that causes the STFT flatlining.

So most probably Fuel Mode 15 should show in the log

1611662036561.png
 
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