N54 big single turbo runs very lean and misfires

[martymil]

If everything is working correctly I'll agree but the #12 Injectors fail all the time and most single turbo kits have two o2's in each bank pre turbo so no point of having 1 unless one has a shitty setup that burns o2's, we don't have that problem.

We are on our 3rd set of injectors, hopefully the Reflex takes the load of them and they stop failing.

 

[Sausage]

I would expect a single turbo to run much better with the change to single bank control. Trying to trim two individual bank of injectors based on a sensor that is reading the combined fuel ratios of both banks is sketchy.

External boost control (for the MAC) and O2 sensor issues were the only thing I didn't really like about single turbo setups. Hopefully now we'll see some good kits come out with updated sensor locations.

I assume you are talking about single scroll setups. Alot of twin scrolls out there now who would deff want to stick with twin banks.
It will be at least a year of trial and error with several sensor types/setups before I would think about switching to single bank. And even then probably won't as it's basically a downgrade. Apart from keeping sensors alive longer.

 

[carabuser]

I assume you are talking about single scroll setups. Alot of twin scrolls out there now who would deff want to stick with twin banks.
It will be at least a year of trial and error with several sensor types/setups before I would think about switching to single bank. And even then probably won't as it's basically a downgrade. Apart from keeping sensors alive longer.

All current single setups are running sub optimal configurations. The DME needs to know the delay between the exhaust pulse leaving the engine and it hitting the upstream O2 sensor so as soon as you move away from stock sensor locations you have a lot of extra work to recalibrate those tables which I don't think anyone bothers with.

MHD are just updating the DME to match the physical configuration most people with a single are running. Without this the DME is trying to control 2 individual banks based off 2 primary sensors that are way too too close to the engine and 2 secondary sensors that are are sat in a combined exhaust outlet.

 

[carabuser]

Also just beceuse your O2 sensors aren't close enough to the engine to get destroyed you still get a decrease in wideband accuracy when they get too hot and I think anywhere pre turbo on a single is going to be too hot.

Combined with the error introduced by having 2 post cat sensors in the same exhaust flow the wideband calibration is going to be screwed. Car might still drive OK but you'll have innacurate afr readings.

 

[Sausage]

All current single setups are running sub optimal configurations. The DME needs to know the delay between the exhaust pulse leaving the engine and it hitting the upstream O2 sensor so as soon as you move away from stock sensor locations you have a lot of extra work to recalibrate those tables which I don't think anyone bothers with.

I'm no tuning expert at all but I cannot imagine this to be true.
No way the stock system with its unequal length manifolds and post-turbo sensors can pick up individual pulses.

 

[carabuser]

I'm no tuning expert at all but I cannot imagine this to be true.
No way the stock system with its unequal length manifolds and post-turbo sensors can pick up individual pulses.

Yes, from memory the DME uses cylinder exhaust specific monitoring for the individual cylinder balancing routine amongst others. Misfire detection is also partly done using it.

 

[Jake@MHD]

I would expect a single turbo to run much better with the change to single bank control. Trying to trim two individual bank of injectors based on a sensor that is reading the combined fuel ratios of both banks is sketchy.

External boost control (for the MAC) and O2 sensor issues were the only thing I didn't really like about single turbo setups. Hopefully now we'll see some good kits come out with updated sensor locations.

Yep, literally 100% of feedback from the beta testers and now those who have converted after official release is that the cars drive, respond, etc noticeably better on single bank.

AFR previously were "close" but no way to make truly accurate with the sensors in the manifold as the heat and pressure there can really skew readings. The compensation table and using ADV sensors made things better, but still that table was based on a function of boost pressure / modeled emap (I forget) in regard to stock turbos config with input axis that maxed at 22.x psi relative.

 

[Jake@MHD]

I'm no tuning expert at all but I cannot imagine this to be true.
No way the stock system with its unequal length manifolds and post-turbo sensors can pick up individual pulses.

It can, it's called CILC (cylinder individual lambda control). It works by richening / leaning one cyl out of the bank of 3 at a time and watching the lambda change and rear o2 change. As soon as you install even aftermarket DP the models are thrown off and should probably be disabled.

 

[carabuser]

I'm no tuning expert at all but I cannot imagine this to be true.
No way the stock system with its unequal length manifolds and post-turbo sensors can pick up individual pulses.

Here's the process description for the cylinder balancing module:

 

[Hutch222]

Yep, literally 100% of feedback from the beta testers and now those who have converted after official release is that the cars drive, respond, etc noticeably better on single bank.

AFR previously were "close" but no way to make truly accurate with the sensors in the manifold as the heat and pressure there can really skew readings. The compensation table and using ADV sensors made things better, but still that table was based on a function of boost pressure / modeled emap (I forget) in regard to stock turbos config with input axis that maxed at 22.x psi relative.

So it seems that single bank control is the way to go then. But with only running the two oxygen sensors linked to the manifold am I able to do this? Or would I need to bring back those rear oxygen sensors also.

 

[martymil]

It can, it's called CILC (cylinder individual lambda control). It works by richening / leaning one cyl out of the bank of 3 at a time and watching the lambda change and rear o2 change. As soon as you install even aftermarket DP the models are thrown off and should probably be disabled.

So whats better if your not burning o2's both primary and secondary o2's installed or going single bank in terms of troubleshooting and monitoring ?

 

[Jake@MHD]

So it seems that single bank control is the way to go then. But with only running the two oxygen sensors linked to the manifold am I able to do this? Or would I need to bring back those rear oxygen sensors also.

For proper single bank, you should run the primary bank 1 sensor moved to the downpipe (near turbine exit), and bank 1 rear o2 sensor at the end of the downpipe where they are usually placed on ST kits.

So whats better if your not burning o2's both primary and secondary o2's installed or going single bank ?

Single bank is still more beneficial due to the more accurate AFRs which will no longer be skewed by the heat/pressure pre-turbo.

 

[wheela]

Here's the process description for the cylinder balancing module:
View attachment 77443

This is very interesting. It sounds like they are describing that a trim value may exist for each cylinder? If that is true, what is the trim per bank that we log? An average of the individual cylinder trims for that bank?

 

[Jake@MHD]

STFT we log are (per bank) the instant percent correction of the actual lambda error (setpoint - target).

CILC is a very small amount to account for minor diffs. Again, not reliable on anything other than fully stock HW imo

 

[wheela]

Okay, so STFT and LTFT corrections are applied to all cylinders of the bank, but then each cylinder also gets a small cylinder-specific CILC correction applied on top of the STFT and LTFT corrections?

 

[Jake@MHD]

Yep

 

[wheela]

Yep

Thanks for explaining that!!

 

[Jern54]

Is it possible to use a ADV sensor just after turbine exit?
Reason to ask is I have 4 pcs on stock...

 

[Jake@MHD]

Is it possible to use a ADV sensor just after turbine exit?
Reason to ask is I have 4 pcs on stock...

I would not, as the ADV flash option has much of the tables configured for the pre-turbo environment (pressure compensation).

 

[martymil]

I would not, as the ADV flash option has much of the tables configured for the pre-turbo environment (pressure compensation).

Our adv's are running perfect and have no issues with them , you can see what each individual bank is doing separately can you still see that with the single bank o2 conversion

Reason I'm asking is also because you can see the stft's of each bank and can tell which injector bank is playing up, making it easy to trouble shoot injectors can that also be seen after the conversion ?