need advice with stft's

iminhell1

Sergeant
Jun 17, 2018
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It says I can only go to 1.6 as a scalar and I don't think it will do anything. I started with a 1.4 across the board, changed the 1.5 sections because they where maxed out. This is the result. Basically no change.

By my rough math my AFR targets are about 10% off. So I'm confused where this 30-35% STFT is coming from. Adjusting to a 1.6 gains my 10% but I'd bet STFT's would still be 25% ... that has been the trend as I've been playing.


I feel like there is something else I'm missing, a mode the car is going into or something (it's all fuel mode 2 and I no throttle closure or knock, no TQ intervention I can see). I've made adjustments I've felt where correct/needed and the same result occurred, repeatedly.

I will change affected to 1.6 and relog. But some advice would help. Something just seems off here.
 

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iminhell1

Sergeant
Jun 17, 2018
345
156
0
Can i assume that I should change the 'base' to relieve reliance on the scalar?
 

iminhell1

Sergeant
Jun 17, 2018
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156
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Here's what 1.6 scalar did ... nothing
 

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bahn

Corporal
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Nov 5, 2016
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Iowa
It says I can only go to 1.6 as a scalar and I don't think it will do anything. I started with a 1.4 across the board, changed the 1.5 sections because they where maxed out. This is the result. Basically no change.

By my rough math my AFR targets are about 10% off. So I'm confused where this 30-35% STFT is coming from. Adjusting to a 1.6 gains my 10% but I'd bet STFT's would still be 25% ... that has been the trend as I've been playing.


I feel like there is something else I'm missing, a mode the car is going into or something (it's all fuel mode 2 and I no throttle closure or knock, no TQ intervention I can see). I've made adjustments I've felt where correct/needed and the same result occurred, repeatedly.

I will change affected to 1.6 and relog. But some advice would help. Something just seems off here.

Lets backup here, what fuel are you running? E85? If so you're using gasoline AFR targets and even though you didn't post a log I bet your fuel pressure is crashing.

I'm all for learning how to tune your own car but make sure you have a good understanding of what you're trying to achieve and how to achieve it. Below are some questions I have:

1) What fuel are you trying to tune on?
2) What mods have been done to the car?
3) What car & transmission type?
 

dyezak

Major
May 4, 2017
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I'm not a Tuna, but this could be you running out of LPFP fuel pressure or HPFP fuel pressure. Do you have a full log we can see?

Oh, and Cobb's scalar table is attached. I think some knowledgable tuners have said it isn't right, but it is what they published circa 2012-2013...
 

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jyamona

Captain
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Nov 7, 2016
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Have you made any changes to the Boost Request Offset table? Any changes there also impact fueling.
 

iminhell1

Sergeant
Jun 17, 2018
345
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Lets backup here, what fuel are you running? E85? If so you're using gasoline AFR targets and even though you didn't post a log I bet your fuel pressure is crashing.

I'm all for learning how to tune your own car but make sure you have a good understanding of what you're trying to achieve and how to achieve it. Below are some questions I have:

1) What fuel are you trying to tune on?
2) What mods have been done to the car?
3) What car & transmission type?


E85
FBO (inlets, 7.5 race, single 450, )
n54 auto

Fuel pressure is lowish 1,000 - 900. And while it does have some impact I don't feel it's the case here. On E30 with better pressures I have the same stft max issue, no matter the scalar. There's something going on that I just can find.

From what i've seen the gas targets are what most use then the scalar to adjust to E blends (kinda figured that'd be self explanatory)
 

iminhell1

Sergeant
Jun 17, 2018
345
156
0
Have you made any changes to the Boost Request Offset table? Any changes there also impact fueling.

I haven't touched it, but it's way different from other bins I compare to. I don't know what stock would look like or what impact it has.
 

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bahn

Corporal
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Nov 5, 2016
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Iowa
E85
FBO (inlets, 7.5 race, single 450, )
n54 auto

Fuel pressure is lowish 1,000 - 900. And while it does have some impact I don't feel it's the case here. On E30 with better pressures I have the same stft max issue, no matter the scalar. There's something going on that I just can find.

From what i've seen the gas targets are what most use then the scalar to adjust to E blends (kinda figured that'd be self explanatory)

The AFR target table is actually a lambda table with AFR being calculated based on a stoich of 14.7 (gasoline). So your 11.728 is a lambda of 0.797 (11.728/14.7). Take a look at the "Conversion" tab under properties for the Fuel (Bank 1 and 2) table, you'll see the math for the function which multiplies by 14.7 (gasoline stoich). Now E85 and Ethanol blends have a different stoich (E85 is around 9.8) so you need to keep that in mind when setting a target AFR. Since you're targeting 11.728 in high-load/rpm that works out to be 0.797 lambda, on E85 that lambda works out to be an AFR of 7.81. Try aiming for a lambda of around .82 - .85 @ high-load/rpm on E85.

Around and below 1000 PSI rail pressure you will start to suffer from poor vaporization of fuel and I suppose it's theoretically possible with very large fuel scalars + a low AFR target to exceed the SOI and EOI (Start and End of injection windows). Although I'd have to research in the BMW documentation to confirm or deny the plausibility of the later.

No need to get defensive, we're trying to help.
 

bahn

Corporal
Platinum Vendor
Nov 5, 2016
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Iowa
I haven't touched it, but it's way different from other bins I compare to. I don't know what stock would look like or what impact it has.

Your Boost Request Offset table looks the same as the stock I8A0S table.
 

iminhell1

Sergeant
Jun 17, 2018
345
156
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So I'm on a completely different tune, still full e85 (same tank infact).
I was chasing the misfire issue. I flashed back to stock then flashed on a new tune based on a different base map. Runs far better, doesn't feel as much power though. Solve fuel issue first, dummy.


STFT's do the same thing. Hit's target, feels strong, STFT flatlines at 34%.

I do have an idea I want to run by you guys though ... could it be an amperage problem?
I'm on the factory stock battery still 2/10. Haven't had any problems I know of, eye is nice bright green still. Car starts every time, even if it sits a few days. But I hear things go strange when the battery starts to get weak. I really don't want to buy one if I don't have to; I'd like to see how far I can push this one.
 

Jeffman

Captain
Jan 7, 2017
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Check your voltage with the ignition on but engine not running using the Check DME Codes screen in MHD or INPA or any tool. I think as long as it’s above 12.0 volts you’re okay. You definitely need to be above 12.0V when flashing.

FWIW, my battery crapped out at exactly 7 years, which I believe is typical.
 

bahn

Corporal
Platinum Vendor
Nov 5, 2016
207
319
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Iowa
So I'm on a completely different tune, still full e85 (same tank infact).
I was chasing the misfire issue. I flashed back to stock then flashed on a new tune based on a different base map. Runs far better, doesn't feel as much power though. Solve fuel issue first, dummy.


STFT's do the same thing. Hit's target, feels strong, STFT flatlines at 34%.

I do have an idea I want to run by you guys though ... could it be an amperage problem?
I'm on the factory stock battery still 2/10. Haven't had any problems I know of, eye is nice bright green still. Car starts every time, even if it sits a few days. But I hear things go strange when the battery starts to get weak. I really don't want to buy one if I don't have to; I'd like to see how far I can push this one.

Have you tried one of the e85 OTS maps? Otherwise pm me your bin file and I'll take a look.
 

iminhell1

Sergeant
Jun 17, 2018
345
156
0
Check your voltage with the ignition on but engine not running using the Check DME Codes screen in MHD or INPA or any tool. I think as long as it’s above 12.0 volts you’re okay. You definitely need to be above 12.0V when flashing.

FWIW, my battery crapped out at exactly 7 years, which I believe is typical.


But Voltage and Amperage are not one in the same.
Voltage always looks good, mid 14's. Without tossing a gauge inline I can't see amperage. I have read that the system (fuse box?) will reduce power to noncritical systems to save critical systems.
The ONLY thing that makes me thing this could be happening is that when I get a working tune, no misfires, feels strong I can not view live data for more than about 30 seconds on my xtrons radio. It just freezes up. But every tune that isn't up to snuff I can view for hours. Strange as that sounds.
I just think there is a ghost in the car somewhere, not sure where to start though.
 

Jeffman

Captain
Jan 7, 2017
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I’m not sure what “factory stock battery still 2/10” means - is Feb 2010 when you got the car? If so, just get a new battery. You’ll need one anyway.
 

iminhell1

Sergeant
Jun 17, 2018
345
156
0
I’m not sure what “factory stock battery still 2/10” means - is Feb 2010 when you got the car? If so, just get a new battery. You’ll need one anyway.

I bought the car used. But the date stamp on the battery is from when it was new. My car is a 2/10 car, last N54 1er made ... came with all the updates, HPFP, injectors and a couple other minor things.
 

Jeffman

Captain
Jan 7, 2017
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I bought the car used. But the date stamp on the battery is from when it was new. My car is a 2/10 car, last N54 1er made ... came with all the updates, HPFP, injectors and a couple other minor things.
Your battery is 8.5 years old. Time for a new one.
 
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