Air Fuel Ratio Commanded lo res - Tuning Forum

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Air Fuel Ratio Commanded lo res
Thursday, July 28, 2011 12:10 PM
What controls Air Fuel Ratio Commanded lo res on the 97 speed density computer? i'm getting 11.4 @ idle & a 1.1 injector pulse width. here is a snapshot. Any idea's? When i drove the car it stayed at 11.4 and went to 12.2 for a second.


Re: Air Fuel Ratio Commanded lo res
Thursday, July 28, 2011 1:07 PM
Is that right when you started it up from cold? Do you have your IPW vs Vac table set to all 1's? You are using the correct PID, but it should not be reading that low if it is has been running for a minute or two.
Re: Air Fuel Ratio Commanded lo res
Thursday, July 28, 2011 1:38 PM
Is that cold, and do you have closed loop disabled? I've found on my car that it will randomly decide to just command super rich all the time when I force closed loop off. Which is why I've started doing all my tuning with closed loop on.


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
Thursday, July 28, 2011 1:53 PM
Leafy (Club Jeffie FEA man) wrote:

Is that cold, and do you have closed loop disabled? I've found on my car that it will randomly decide to just command super rich all the time when I force closed loop off. Which is why I've started doing all my tuning with closed loop on.
This has been a known issues, and HPT refused to get us the correct tables...





P&P Tuning
420.5whp / 359.8wtq

Re: Air Fuel Ratio Commanded lo res
Thursday, July 28, 2011 1:56 PM
I wish I knew how to pull binary files. I would eventually find the area we needed (along with the damn re-scaling and define the fuel map sensor location) and shove the correct hex location down support@hptuners.com's throat.


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
Thursday, July 28, 2011 2:30 PM
No the car wasn't cold. I warmed up the car to operating temp, then i shut it off hooked everything up. I started it started scanning it and noticed the com afr, i thought it was like that because i restarted it. So i drive it around, but it never changed off 11.4. I got the ect vs startup ect set to 256. should i just put back to close loop and try tuning that way?
Re: Air Fuel Ratio Commanded lo res
Thursday, July 28, 2011 2:38 PM
I would switch to tuning by using closed loop. Make the LTFT + STFT custom pid. Remake your low rpm ve, idle ve, and coast down ve tables and graph that pid. But add the filter of cmd afr >14. And then on the histograms using afr error add the filter of cmd afr < 14. Thats my huge secret now, and for me it worked out a lot better/faster than using afr error for stuff that would be controlled by the narrowband anyways.


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
Thursday, July 28, 2011 3:11 PM
Thanks, I changed it now i just got to up load it and try it.
Re: Air Fuel Ratio Commanded lo res
Friday, July 29, 2011 4:36 AM
Long shot, but does it have anything to do with the really high IATs?



Re: Air Fuel Ratio Commanded lo res
Friday, July 29, 2011 6:16 AM
That's actually a good possibility.


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
Friday, July 29, 2011 9:59 AM
its was 103 degrees with 61% humidity yesterday.

Re: Air Fuel Ratio Commanded lo res
Friday, July 29, 2011 5:17 PM
What do i do with the info, i understand when you do the afr error, but ltft +stft.
Re: Air Fuel Ratio Commanded lo res
Friday, July 29, 2011 5:23 PM
If those are ltft +stft or wideband AFR error - copy the whole table and go to the corresponding VE table, right click, and go to paste special multiply by percent. It will most likely make your table look choppy, so either click the smooth button or do it by hand in the 3D view.
Re: Air Fuel Ratio Commanded lo res
Friday, July 29, 2011 5:28 PM
I don't copy the whole table, I only use the ltft table at less throttle position than pe mode and use the wide band one above pe enable threshold.


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
Friday, July 29, 2011 6:02 PM
Could someone elaborate on thus situation? I do not see why its so confusing that it commands a low AFR when forced into open loop. This is by design...

Quote:

Is that cold, and do you have closed loop disabled? I've found on my car that it will randomly decide to just command super rich all the time when I force closed loop off. Which is why I've started doing all my tuning with closed loop on.


This is by design...before you enter closed loop the PCM will command a rich AFR and run strictly off of fuel tables, that's why if your tuning the fuel tables I do not see why you would ever want to leave closed loop on.

Ryan I know you touched on this when we did my car, and I'm wondering if this is not related to some of the quirks I have been having lately in the lower load cells with regards to drive-ability.

Quote:

No the car wasn't cold. I warmed up the car to operating temp, then i shut it off hooked everything up. I started it started scanning it and noticed the com afr, i thought it was like that because i restarted it. So i drive it around, but it never changed off 11.4. I got the ect vs startup ect set to 256. should i just put back to close loop and try tuning that way?


It runs at that commanded AFR BECAUSE you have closed loop disabled.

Please advise... This is coming from a vast understanding of how Powertrain management is supposed to work from the factory, some of what you guys are telling me seems a little backwards... Don't mean any offense to anyone (Especially my buddeh Ryan there!) cause he made a whole new car out of mine with regards to the top end and PE cells... but driveability has declined slightly and I have to wonder about the theory behind this. I just don't smell what ya'll are cookin'



Buildin' n' Boostin for 08' - Alex Richards
Re: Air Fuel Ratio Commanded lo res
Friday, July 29, 2011 6:04 PM
Speaking of which, Ryan, I may send you a log I'm going to try and get this weekend regarding the issues I am having...I'd like to brainstorm with ya over it for a bit if your willing.



Buildin' n' Boostin for 08' - Alex Richards
Re: Air Fuel Ratio Commanded lo res
Friday, July 29, 2011 6:23 PM
Ok so i use the ltft+stft for idle and low ve up to 2200 rpm, then i use afr error for the rest.
Re: Air Fuel Ratio Commanded lo res
Friday, July 29, 2011 6:29 PM
subed



Re: Air Fuel Ratio Commanded lo res
Friday, July 29, 2011 6:32 PM
I user it for a lot more than that. The whole low rpm range and below my pe tps threshold.


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
Friday, July 29, 2011 6:52 PM
Personally, I do the whole thing with the wideband AFR error first. After I have it close, I go back and get the fuel trims (at lower throttle and RPM's) as close to zero as I can using the narrowband. I think everyone has their own way of tackling things (and a few tricks up their sleeve).
Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 3:21 AM
Alex, every other car i've seen commands 14.0:1 in open loop when not in PE, although i've seen some weird PE engagement in automatic cars, but that is not the case here.

I agree with Leafy - whenever possible, i tune maybe one or two flashes in open loop, then everything proceeding in closed loop. The more highly modified the engine is (cams for example), the easier it makes life. You can make good use of filters to keep fuel trim data and afr error data in their respective histograms. For example, filter PID6000=14.6 for closed loop (LTFT+STFT), and filter PID6000 < 14.6 for PE (AFR error from wideband). There are about two or three other filters involving speed, TPS, and wideband afr, but you get the idea.




Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 6:18 AM
oldskool wrote:

I agree with Leafy - whenever possible, i tune maybe one or two flashes in open loop, then everything proceeding in closed loop. The more highly modified the engine is (cams for example), the easier it makes life. You can make good use of filters to keep fuel trim data and afr error data in their respective histograms. For example, filter PID6000=14.6 for closed loop (LTFT+STFT), and filter PID6000 < 14.6 for PE (AFR error from wideband). There are about two or three other filters involving speed, TPS, and wideband afr, but you get the idea.
Agreed! If you are tuning the cells in OL and its commanding a whack AFR, you are basically just wasting time and money on fuel.... Filters are your friend!


Alex, send me what you got. More than happy to help you out!




P&P Tuning
420.5whp / 359.8wtq

Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 6:27 AM
Did most of us just actually agree on a tuning technique? I need to like go buy a lottery ticket or prepare for the end of the world or something.


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 6:35 AM
^ LMAO indeed!



Re: Air Fuel Ratio Commanded lo res
Saturday, July 30, 2011 6:36 AM
Leafy (Club Jeffie FEA man) wrote:

Did most of us just actually agree on a tuning technique? I need to like go buy a lottery ticket or prepare for the end of the world or something.
lmao....





P&P Tuning
420.5whp / 359.8wtq

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