Air Fuel Ratio Commanded lo res - Page 2 - Tuning Forum

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Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 8:24 AM
The last 2 cars I have tuned I have went to not even tuning at all in open loop. All tuning is in closed loop. I just disable DFCO. I do not use any of those filters either. I believe it does not matter what the ECU is targeting AFR wise to get the VE tables tuned in right. I do not mean that is never matters what the ECU is targeting AFR wise, but as long as the command is X and your AFR reading is the same X your good.

Doing this has giving me good results, and STFT and LTFT are always good.

I know Ryan and I have talked about the missing files we do not have that allows the ECU to change the command AFR, and it would be nice to have access to those files, but I do not think it keeps us from having a very good tune.



FU Tuning




Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 9:00 AM
I use the afr commanded fikter to keep the non-pe stuff out of my low rpm afr error histo. I also use speed and tps filters on all the tables to keep idle map stuff out of the low rpm ve and out of coast down stuff.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

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WPI SAE Risk and Sustainability Management Officer
Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 10:46 AM
Quote:


I use the afr commanded fikter to keep the non-pe stuff


This is the part I was saying I do not think it matters if you are in PE or not.

I believe if 3200 RPMs at 15% TPS is good in non PE it will be good in PE (This was just a example). We only have 1 set of VE files, unlike timing tables we have PE and non PE.



Seems to be working for me.



Edited 1 time(s). Last edited Saturday, July 30, 2011 10:50 AM


FU Tuning



Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 10:50 AM
Right, but it keeps me from double adding the same cells, and it seems that the car is slow at times to turn the fuel trims off even though I'm I'm pe, mode.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 6:34 PM
I cant get it to work, I started to clean up the idle table, I was using the ltft + stft table. Then multiplying by %, and hitting smooth twice. Now the car dies, it barely idles. I was running rich so i was going to clean and re cal my o2 sensor, but what am i doing wrong?
Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 6:43 PM
Spook 427 wrote:

I cant get it to work, I started to clean up the idle table, I was using the ltft + stft table. Then multiplying by %, and hitting smooth twice. Now the car dies, it barely idles. I was running rich so i was going to clean and re cal my o2 sensor, but what am i doing wrong?


There is an idle re-learn that needs to happen. Keep your foot on the gas to keep it from stalling, it can take up to a minute to relearn sometimes.
Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 6:59 PM
when i would get it stay running it would hunt for idle. it would stumble then go up, and come down and stumble.
Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 7:12 PM
Spook 427 wrote:

I cant get it to work, I started to clean up the idle table, I was using the ltft + stft table. Then multiplying by %, and hitting smooth twice. Now the car dies, it barely idles. I was running rich so i was going to clean and re cal my o2 sensor, but what am i doing wrong?


I would not use stft and ltft for this.

Regardless of how you do it I would start over with a stock idle ve file.



FU Tuning



Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 7:28 PM
Should I use the afr error for my idle, and use ltft+stft on low tables
Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 7:32 PM
Spook 427 wrote:

Should I use the afr error for my idle, and use ltft+stft on low tables


If it was me I would use afr error for everything.



FU Tuning



Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 7:44 PM
The fuel trims is perfect for idle, but you're supposed to use add not multiply, just like it was an afr error. Mine hints for idle, but barely and only recently had it stated, got now I'm blaming it on a clogged cat. I also found that if I have the idle table with prefect fuel trims the car won't start, a 3 to the most common idle cells and it starts right up.

On another note, after flashing a tune do tune test of you notice that the car runs super lean until you drive it for a few minutes and go over 35?


Edit, you can't use afr error when the car is in closed loop mode.


Edited 1 time(s). Last edited Saturday, July 30, 2011 7:46 PM

1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer

Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 8:02 PM
Quote:


Edit, you can't use afr error when the car is in closed loop mode.


You can't? Why not?



FU Tuning



Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 8:04 PM
Ok I will start over and add not multiply the fuel trims. I was wondering why my tables went all over the place after 2 flashes.
Re: Air Fuel Ratio Commanded lo res
Sunday, July 31, 2011 6:55 AM
Screaming for Mercy!! wrote:

Quote:


Edit, you can't use afr error when the car is in closed loop mode.


You can't? Why not?


Think about how fuel trims work. When you are in closed loop the car figures out how much fuel to use by; adding the LTFT to the STFT and then adding that to the cell its in on the VE map, then figures out fueling based off the VE number. So the afr error from that point is completely wrong, hell you could have a negative afr error number but fuel trims that are adding and you'd be going in the wrong direction with your tune.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
Re: Air Fuel Ratio Commanded lo res
Sunday, July 31, 2011 7:08 AM
Leafy (Club Jeffie FEA man) wrote:


The fuel trims is perfect for idle, but you're supposed to use add not multiply, just like it was an afr error.


I have never done this. I am quite sure you are supposed to multiply by percent. The fuel trims are a percentage difference from stoich, not the amount of volumetric efficiency that is being added or subtracted. By that logic you would also paste special add for wideband AFR error, they are essentially the same as far as I am aware. So you would multiply by percent.

See post number 6: http://www.hptuners.com/forum/showthread.php?t=18622&highlight=paste+special+add

Not trying to start anything, but I have always multiplied by percent and have never had issues. If Bill actually is wrong, I have been tuning incorrectly for some time now and had it work out fine for me.

Screaming for Mercy!! wrote:


Leafy (Club Jeffie FEA man) wrote:


Edit, you can't use afr error when the car is in closed loop mode.

You can't? Why not?


Because the narrowband O2 will be trimming, making your fuel trims look bad and your AFR error look good (commanded 14.7, and the wideband reads 14.7 because the fuel trims).
Re: Air Fuel Ratio Commanded lo res
Sunday, July 31, 2011 7:12 AM
To further prove the point of what fuel trims are - on a MAF car, you obviously don't add 5 or 10 (for example) to the MAF frequency table. You multiply by percent. MAF isn't VE, and people have the paste special multiply by LTFT + STFT on MAF cars.
Re: Air Fuel Ratio Commanded lo res
Sunday, July 31, 2011 7:21 AM
Yes you multiply on MAF tables, but with VE you're supposed to add. When putting similar things together you add, when doing different things you multiply. IE MAF you are changing a value related to hertz with a value based off of VE, where are with VE you're changing a VE value with a value based off VE.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
Re: Air Fuel Ratio Commanded lo res
Sunday, July 31, 2011 7:47 AM
According to Bill you multiply by percent for VE tuning as well...

As far as I know the way fuel trims are calculated are INDEPENDENT of the PCM being MAF or SD based. What about the cars (LS1) that have VE tables and MAF tables? You are telling me that you add for one and multiply for the other? Fuel trims are the last step of the IPW calculation, and they get added together and multiplied by the calculated IPW to get final IPW. Adding would never make any sense.
Re: Air Fuel Ratio Commanded lo res
Sunday, July 31, 2011 8:20 AM
Quote:


By that logic you would also paste special add for wideband AFR error


This is exactly what I do. The way I was taught. Lots of talk about this years ago as well.

Quote:

Because the narrowband O2 will be trimming, making your fuel trims look bad and your AFR error look good (commanded 14.7, and the wideband reads 14.7 because the fuel trims).


See to me if your tuning from the STFT and LTFT or from the wideband your still trying to achieve the same thing.

I realize the trims are trying to correct things themselves, but it you use the wideband, and smooth it works fine. Works better in my mind. Too many times I have tuned in open loop had everything perfect, then put the car in closed loop and fuel trims are wacked and car runs like @!#$. So since tuning in closed loop using the wideband things work soo much better.



FU Tuning



Re: Air Fuel Ratio Commanded lo res
Sunday, July 31, 2011 10:18 AM
LoL.... I'm loving this..... Some of this I even covered in the "how to" I'm working on...
Wagonwes wrote:



Screaming for Mercy!! wrote:


Leafy (Club Jeffie FEA man) wrote:


Edit, you can't use afr error when the car is in closed loop mode.

You can't? Why not?


Because the narrowband O2 will be trimming, making your fuel trims look bad and your AFR error look good (commanded 14.7, and the wideband reads 14.7 because the fuel trims).

If using a WB and the proper histograms, you CAN! I have done it this way for years...

Wagonwes wrote:

Leafy (Club Jeffie FEA man) wrote:


The fuel trims is perfect for idle, but you're supposed to use add not multiply, just like it was an afr error.


I have never done this. I am quite sure you are supposed to multiply by percent. The fuel trims are a percentage difference from stoich, not the amount of volumetric efficiency that is being added or subtracted. By that logic you would also paste special add for wideband AFR error, they are essentially the same as far as I am aware. So you would multiply by percent.

See post number 6: http://www.hptuners.com/forum/showthread.php?t=18622&highlight=paste+special+add

Not trying to start anything, but I have always multiplied by percent and have never had issues. If Bill actually is wrong, I have been tuning incorrectly for some time now and had it work out fine for me.



Here is one for you guys..... Try it adding, take a screen shot, then UNDO and try it my Multiplying.... Compare and see what you get... It will be damn near identical..... Myself and Joe Rutledge came across this and had a very lenghty discussion on this about a year ago.... Technically, you are supposed to Multiply based on the % error and the Special Paste being a % also... As far as I'm concerned, its a personal choice when it comes to this topic and our sh!tty PCM.....

Screaming for Mercy!! wrote:

Quote:

Because the narrowband O2 will be trimming, making your fuel trims look bad and your AFR error look good (commanded 14.7, and the wideband reads 14.7 because the fuel trims).


See to me if your tuning from the STFT and LTFT or from the wideband your still trying to achieve the same thing.

I realize the trims are trying to correct things themselves, but it you use the wideband, and smooth it works fine. Works better in my mind. Too many times I have tuned in open loop had everything perfect, then put the car in closed loop and fuel trims are wacked and car runs like @!#$. So since tuning in closed loop using the wideband things work soo much better.
Been there, done that..... Gotta agree!





Edited 1 time(s). Last edited Sunday, July 31, 2011 10:20 AM


P&P Tuning
420.5whp / 359.8wtq

Re: Air Fuel Ratio Commanded lo res
Sunday, July 31, 2011 11:37 AM
QWK LN2 (P&P Tuning) wrote:

LoL.... I'm loving this..... Some of this I even covered in the "how to" I'm working on...
Wagonwes wrote:



Screaming for Mercy!! wrote:


Leafy (Club Jeffie FEA man) wrote:


Edit, you can't use afr error when the car is in closed loop mode.

You can't? Why not?


Because the narrowband O2 will be trimming, making your fuel trims look bad and your AFR error look good (commanded 14.7, and the wideband reads 14.7 because the fuel trims).

If using a WB and the proper histograms, you CAN! I have done it this way for years...

If you are using filters, sure it can be done, didn't say you couldn't. Without filters, it would be incredibly hacked I would think.

Wagonwes wrote:

Leafy (Club Jeffie FEA man) wrote:


The fuel trims is perfect for idle, but you're supposed to use add not multiply, just like it was an afr error.


I have never done this. I am quite sure you are supposed to multiply by percent. The fuel trims are a percentage difference from stoich, not the amount of volumetric efficiency that is being added or subtracted. By that logic you would also paste special add for wideband AFR error, they are essentially the same as far as I am aware. So you would multiply by percent.

See post number 6: http://www.hptuners.com/forum/showthread.php?t=18622&highlight=paste+special+add

Not trying to start anything, but I have always multiplied by percent and have never had issues. If Bill actually is wrong, I have been tuning incorrectly for some time now and had it work out fine for me.



Here is one for you guys..... Try it adding, take a screen shot, then UNDO and try it my Multiplying.... Compare and see what you get... It will be damn near identical..... Myself and Joe Rutledge came across this and had a very lenghty discussion on this about a year ago.... Technically, you are supposed to Multiply based on the % error and the Special Paste being a % also... As far as I'm concerned, its a personal choice when it comes to this topic and our sh!tty PCM.....

I was just going to comment the same thing... I was making a little excel table to illustrate (arbitrary values used):

VE.....Wideband AFR Error (percent)....Multiply by Percent ..........Add
50............................ -5............................................47.5.....................45
75........................... 10............................................82.5.....................85
100......................... 18............................................118....................118
125........................ -10............................................112.5................115
150........................ -25............................................112.5................125

You can see that they are all fairly close, especially near 100 percent VE. However in the higher VE numbers there can be a size-able gap that could be fairly problematic in some situations. I understand that I am splitting hairs, but there is a correct way to do things, and technically you are supposed to multiply.


Screaming for Mercy!! wrote:

Quote:

Because the narrowband O2 will be trimming, making your fuel trims look bad and your AFR error look good (commanded 14.7, and the wideband reads 14.7 because the fuel trims).


See to me if your tuning from the STFT and LTFT or from the wideband your still trying to achieve the same thing.

I realize the trims are trying to correct things themselves, but it you use the wideband, and smooth it works fine. Works better in my mind. Too many times I have tuned in open loop had everything perfect, then put the car in closed loop and fuel trims are wacked and car runs like @!#$. So since tuning in closed loop using the wideband things work soo much better.
Been there, done that..... Gotta agree!

If you are using filters it is a perfectly acceptable way of getting the job done, I agree as well.


Re: Air Fuel Ratio Commanded lo res
Friday, August 12, 2011 8:47 PM
Ok so I did some logs and what I noticed if I compare ltft+stft and afr error, one says to add fuel the other says subtract and vise versa. Shouldn't they both be going in the same direction?

Re: Air Fuel Ratio Commanded lo res
Saturday, August 13, 2011 3:22 AM
Are you using a the generic AFR error PID, or custom? If it's custom make sure your sign (+/-) is right Also, are the histograms filtered? If not i would filter the LTFT+STFT for PID.6000=14.6, and filter the AFR error histo for PID.6000 < 14.0 or something similar.



Re: Air Fuel Ratio Commanded lo res
Saturday, August 13, 2011 7:09 AM
Its custom, and those are the filters I'm running, except AFR error is 14.6
Re: Air Fuel Ratio Commanded lo res
Saturday, August 13, 2011 7:16 AM
I hate using = in a filter. I'd much rather use > or < in case there is some fluctuation or a digit missing that we dont see. Its real important to do with tps.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
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