High RPM Cylinder 6 Misfire

sman217

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Oct 31, 2022
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if my car is on older tunes on lower boost it didnt have this problem. I can flash it it itll be fine.

it seems to be high hp only, and im not sure its relative to the injectors functionality because you also need to remember, my helix 3x had the same issue at same boost, and the di injectors were being taxed WAY more on that power. David and i have leaned heavily on Pi to test if it was a Di issue and the issue remained the same. 3rd gear doesnt seem to care about the issue (or lackthereof) and i can rev 3rd out to 6800-6900, 4th though doesnt play nicely over 6300 rpm.
 

bernardo774

Lurker
Aug 15, 2022
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Hello!
I have the same case with one custumer.
FBO car, with E50 tune and 21psi of max boost.

After 6.500 the 6 cylinder shutoff, like the log in first post.

We change injector, hpfp, everething....no change.

So i dicide to tune max rpm to 6.400 and no problens, since 1 year.

The car is: 2009 ijeos ZF6 with xhp stg3.
 

sman217

Private
Oct 31, 2022
26
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0
Hello!
I have the same case with one custumer.
FBO car, with E50 tune and 21psi of max boost.

After 6.500 the 6 cylinder shutoff, like the log in first post.

We change injector, hpfp, everething....no change.

So i dicide to tune max rpm to 6.400 and no problens, since 1 year.

The car is: 2009 ijeos ZF6 with xhp stg3.
but that means the customer cant rev past 6400, am i understanding you correctly?

did you try disabling misfire detection
 

carabuser

Lieutenant
Oct 2, 2019
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Z4 35i & 335i
I'm wondering if this is due to crank twist, causing the power stroke from the piston to fall outside the allowable window for misfire detection? There must be some map for the misfire window? Here's what I posted over on 1addicts on @houtan thread:

As misfire is detected by the crank position sensor, I suspect there is some interaction between the motor and DCT at high power levels where crank twist causes the misfire detection to erroneously trip. I doubt the DME compensates for crank twist, so it seems plausible that as crank twist increases, there would be a point where the contributions from the various cylinders' power stroke would appear to not be happening at the correct time based on crank position (if the crank is twisting, then the end of the crank opposite the crank position sensor will be at a worst-case different rotational position than indicated by the crank position sensor - it would be further off the further you get from the crank position sensor). This is also why I suspect you can influence the problem by changing fly wheels - the different rotational inertia would influence the crank twist harmonics. I have no hard proof to back it up, this is just my theory.

@carabuser Have you come across any maps like this?
I've not defined any of those tables yet. The first step would be for someone with the issue to be able to go through several rounds of logging custom channels to narrow down the cause.

There's a few possible causes. I think the most common one that I see in logs is the fuel mode 15 one which is usually triggered by knock detection. If someone has this issue and it's not knock related then i'd happily attempt to find the cause.
 
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martymil

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Sep 6, 2017
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I've not defined any of those tables yet. The first step would be for someone with the issue to be able to go through several rounds of logging custom channels to narrow down the cause.

There's a few possible causes. I think the most common one that I see in logs is the fuel mode 15 one which is usually triggered by knock detection. If someone has this issue and it's not knock related then i'd happily attempt to find the cause.

My mates car does it exactly 6500rpm every time, we isolated a problem to the exhaust vanos not working properly and getting stuck.

If it persists I can help you with logging and isolating the problem if you like after he is done fixing the issue with the vanos if someone else cant.

Just have to wait for his mechanic to do the fix and do all the checks he needs to do.
 

sman217

Private
Oct 31, 2022
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My mates car does it exactly 6500rpm every time, we isolated a problem to the exhaust vanos not working properly and getting stuck.

If it persists I can help you with logging and isolating the problem if you like after he is done fixing the issue with the vanos if someone else cant.

Just have to wait for his mechanic to do the fix and do all the checks he needs to do.
I’d be interested in seeing how you came to this conclusion. I have had a vanos cel in the past but not recently.
 

sman217

Private
Oct 31, 2022
26
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I've not defined any of those tables yet. The first step would be for someone with the issue to be able to go through several rounds of logging custom channels to narrow down the cause.

There's a few possible causes. I think the most common one that I see in logs is the fuel mode 15 one which is usually triggered by knock detection. If someone has this issue and it's not knock related then i'd happily attempt to find the cause.
My knock sensors are turned off and it still threw FM15. We “fixed” by disabling misfire detection over 6000
 

martymil

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Sep 6, 2017
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I’d be interested in seeing how you came to this conclusion. I have had a vanos cel in the past but not recently.
You can see it in the logs, target and actuall are no where near each other as it ust flatlines and is about 10deg off target.
 

carabuser

Lieutenant
Oct 2, 2019
908
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My knock sensors are turned off and it still threw FM15. We “fixed” by disabling misfire detection over 6000
There are a few different causes of fuel mode 15. Did you explicitly disable knock control and detection or did the tuner just adjust the standard sensitivity tables in the XDF?
 

TOR COILS

Private
Jul 3, 2019
27
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Ride
n55
if my car is on older tunes on lower boost it didnt have this problem. I can flash it it itll be fine.

it seems to be high hp only, and im not sure its relative to the injectors functionality because you also need to remember, my helix 3x had the same issue at same boost, and the di injectors were being taxed WAY more on that power. David and i have leaned heavily on Pi to test if it was a Di issue and the issue remained the same. 3rd gear doesnt seem to care about the issue (or lackthereof) and i can rev 3rd out to 6800-6900, 4th though doesnt play nicely over 6300 rpm.

I have a tune from david that disables misfire detection over 6000 rpm to see if that causes issue. if that doesnt fix it, and there is still active misfiring, i will absolutely lean on the side of actual misfire.
hi,disables misfire detection over 6000 rpm solved the problem?
 

houtan

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Nov 2, 2017
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My knock sensors are turned off and it still threw FM15. We “fixed” by disabling misfire detection over 6000
Can someone please show what tables you use to turn off misfire detection? As @wheela mentioned I have a similar issue when I creek up to 600whp on my e series DCT n55.

I have tried to disable all cel but it still happens so my guess is the table is not correct. I have also softened cyl 4, 5, 6 knock detection at high load and also average knock detection for those cylinders. Same issue.

I don’t have an actual misfire, it just throws the code which on my dme is 65536 in the log.
 

Asmo

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Aug 23, 2020
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Can someone please show what tables you use to turn off misfire detection? As @wheela mentioned I have a similar issue when I creek up to 600whp on my e series DCT n55.

I have tried to disable all cel but it still happens so my guess is the table is not correct. I have also softened cyl 4, 5, 6 knock detection at high load and also average knock detection for those cylinders. Same issue.

I don’t have an actual misfire, it just throws the code which on my dme is 65536 in the log.
WIP - Testing > Misfire Detection Max RPM (AT/MT)
 
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houtan

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Nov 2, 2017
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WIP - Testing > Misfire Detection Max RPM (AT/MT)
Thank you. It would be nice to know why this even happens but my guess is we will never get an answer. In the meantime, we are going to look for that table for the E series N55.