Datalog Help with FBO N54. (Stuttering/Lagging)

[ClaytonT]

Hi there

I am unsure if this is the right place for this but my N54 is lagging/stuttering under boost, feels underpowered and just in general isn’t really running right and I don’t know what it could be. I replaced spark plugs and coils recently but it’s still not right. I’m thinking maybe the gap isn’t correct, or the turbos are on their way out? It’s strange because it feels like a misfire coming on but then the car powers through and smooths out in the higher revs.I don’t know.

Would anyone be able to have a look at the log and see what they think?

E92 N54 Stage 2+ 91oct
110,000 miles
FBO

Spark plugs:
NGK 97506
Gapped to .022

Coils:
Bavarian Autosport 5005

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[odesh]

The one thing I noticed that is odd is that the AFRs are around 18 under 4700rpm, so way too lean. After that the AFR normalize and that's why "car smooths out in higher revs", just like you said. Have you read if the car has any fault codes? I'm just afraid that I can't really say what might cause that kind of issue. Vacuum leak? Problem with O2 sensors? Hopefully someone with bigger brain could help.

Also there are random throttle closures, but that could just be traction control being on.

 

[ClaytonT]

The one thing I noticed that is odd is that the AFRs are around 18 under 4700rpm, so way too lean. After that the AFR normalize and that's why "car smooths out in higher revs", just like you said. Have you read if the car has any fault codes? I'm just afraid that I can't really say what might cause that kind of issue. Vacuum leak? Problem with O2 sensors? Hopefully someone with bigger brain could help.

Also there are random throttle closures, but that could just be traction control being on.

Thanks for your help! unfortunatelyit doesn’t show any codes, only recent one was a misfire when I suppose it leaned out! The injectors are index 12 but maybe too old or possibly blocked? or maybe a walnut blast could solve something like that ?

 

[odesh]

Thanks for your help! unfortunatelyit doesn’t show any codes, only recent one was a misfire when I suppose it leaned out! The injectors are index 12 but maybe too old or possibly blocked? or maybe a walnut blast could solve something like that ?

Just checking. Have the Index 12s been coded into the car? If they have, I would try resetting O2 adaptations trough MHD. There have been weird issues with AFRs that have been fixed by resetting O2 adaptations or all adaptations.

Good luck!

 

[BloodyZ4]

Your STFT's are pegged at max 34%, you def have some problem with your injectors or maybe O2s reading wrong, since Rail and Low pressure are ok. Car leans out because the DME can't add more fuel. You can see as soon as your STFT's go down AFRs get richer again.

 

[wheela]

Your STFT's are pegged at max 34%, you def have some problem with your injectors or maybe O2s reading wrong, since Rail and Low pressure are ok. Car leans out because the DME can't add more fuel. You can see as soon as your STFT's go down AFRs get richer again.

Building in this, your rail pressure looks okay in the log, but the sensor itself could be reading incorrectly. You stft% go from pegged at the start of the pull (and super lean), and around 5200 rpm they switch to going negative and pulling fuel out.

I just had my rail pressure sensor replaced a few weeks ago, it was actually reading 5 bar when the rail wasn't even connected to the hpfp.

 

[SLOWESTN54]

I'd start with replacing the Rail Pressure sensor as @wheela mentioned. Are you sure you have the correct fuel in the car as well.

 

[SLOWESTN54]

And do not floor it again until you sort it out, 19 Afrs is destroying pistons territory. Edit also add fuel mode if you do another log

 

[ClaytonT]

Just checking. Have the Index 12s been coded into the car? If they have, I would try resetting O2 adaptations trough MHD. There have been weird issues with AFRs that have been fixed by resetting O2 adaptations or all adaptations.

Good luck!

Thanks! I’ve had the car now for four years and it’s had those injectors this whole time so I can’t say if they’ve been coded but car was running fine just a few weeks ago. I’ll reset adaptations today and get back to you

 

[ClaytonT]

Building in this, your rail pressure looks okay in the log, but the sensor itself could be reading incorrectly. You stft% go from pegged at the start of the pull (and super lean), and around 5200 rpm they switch to going negative and pulling fuel out.

I just had my rail pressure sensor replaced a few weeks ago, it was actually reading 5 bar when the rail wasn't even connected to the hpfp.

Okay thank you, I’ll order one now and install it this week. Is there a way to test if the injectors are blocked? Or a way to test if the problem has been fixed without doing another pull and risking blowing it up? Thanks

 

[ClaytonT]

A

I'd start with replacing the Rail Pressure sensor as @wheela mentioned. Are you sure you have the correct fuel in the car as well.

Okay cool, I’m in NZ and always run either 98RON or 100RON. The tune is for 95RON so I hope this is okay? also is there a way to check if the problem has been fixed without doing another pull and blowing it up ? thank you

 

[SLOWESTN54]

A


Okay cool, I’m in NZ and always run either 98RON or 100RON. The tune is for 95RON so I hope this is okay? also is there a way to check if the problem has been fixed without doing another pull and blowing it up ? thank you

I'd recommend Having afr's open on your phone screen. and if you see it touch over 16 you lift.

 

[wheela]

I'd recommend Having afr's open on your phone screen. and if you see it touch over 16 you lift.

Also keep at eye on stft% - general rule of thumb is within +/- 5% is ideal.

 

[ClaytonT]

Also keep at eye on stft% - general rule of thumb is within +/- 5% is ideal.

I just reset all adaptations and as crazy as it sounds… I think it’s fixed. Car feels way way way better than it did. I took a log, what do you guys think?

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[odesh]

I just reset all adaptations and as crazy as it sounds… I think it’s fixed. Car feels way way way better than it did. I took a log, what do you guys think?

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Great to hear that resetting adaptations helped and that the car feels better now. The log looks way better now. AFRs are around 14.5 "idle/cruising state" on low rpm and around 12 on WOT like it should be. Hopefully it stays like that!

STFTs still looks little weird, but it could be that the car is still learning stuff after the adaptation reset.

 

[BloodyZ4]

Can you also do a log with fuel mode, load? Did you have TC enabled, because your accel pedal doesn't go over 56% in this log?
For my liking 12 AFR is a tad too lean for piss poor 91 fuel, I would have thought they target more like 11.5 - 11.7, but maybe someone can comment if thats normal on MHD V10, haven't been on stock turbos for like 3 years.

 

[odesh]

Can you also do a log with fuel mode, load? Did you have TC enabled, because your accel pedal doesn't go over 56% in this log?
For my liking 12 AFR is a tad too lean for piss poor 91 fuel, I would have thought they target more like 11.5 - 11.7, but maybe someone can comment if thats normal on MHD V10, haven't been on stock turbos for like 3 years.

I didn't even notice that it was on 91. You are right, it should be closer to 11 than 12. I was talking about 93oct.

Also his throttle body seems to open normally, even tho it looks like he has traction control on. You shouldn't watch the pedal output since it's just the signal what it's sending, not the actual throttle body opening state.

 

[BloodyZ4]

Yeah I know, but I found it strange in comparisson to his first log, there it goes up to 100%.
Must drive like shit getting WOT with only 55% pedal position?

 

[wheela]

Yeah I know, but I found it strange in comparisson to his first log, there it goes up to 100%.
Must drive like shit getting WOT with only 55% pedal position?

Yeah, I noticed that too...

 

[ShocknAwe]

Could be a physical kickdown blocker.

Nice that adaptation reset fixed things but I suspect it'll come back. Maxed out trims and lean conditions across both banks reeks of a vac leak. Cruise pressure only -2 on log and should be ~ -8 under partial and -11 at idle.