Air fuel code for scangauge

Jordo! · 06-18-2010, 04:45 PM

Quote:

Originally Posted by JvKintheUSA

Thanks Mod! Did a quick highway run and it seems that the coding on the Scangauge was incorrect. On the setting that you provided, I now read an A/F ration at WOT of 12.8 to 12, depending on RPM. Long term fuel trim stuck at 34 though..another issue I guess?!

That's a relief! That's perfectly safe and not too far off from the likely best torque AFR (varies from motor to motor, but something around 13.2 is generally ideal N/A).

Congrats!

If you want to learn more about this stuff, I highly recommend you pick up the following text:

Amazon.com: Engine Management: Advanced Tuning (9781932494426): Greg Banish:…

It really spells out all of the basics with some clear information on more advanced topics. It will help clarify what the scanguage is telling you.

Also, regarding fuel trims, note that there are most likely multiple trims --one associated with each cell in the fueling map (which you probably can't access) or at least a block of adjacent cells; cells are graphed by load (based on MAF value and known engine displacement) and RPM.

Short term trims (based on vacilations around 14.68 AFR / narrow band .5 volts) are averaged to create long term trims. One of those is probably carried into open loop (can Modshack confirm or refute that?)

The LTFT of +34 may or may not be a cause for concern. So long as driveability is fine, AFR's in WOT are fine, and the CEL light is off, it's not ideal, but acceptable (ideally, you'd want to have th ecar tuned so that these are all in the single digits and driveability is excellent).

Man, I can't wait to start playing with uprev on this car

JvKintheUSA · 06-18-2010, 04:54 PM

Quote:

Originally Posted by Jordo!

That's a relief! That's perfectly safe and not too far off from the likely best torque AFR (varies from motor to motor, but something around 13.2 is generally ideal N/A).

Congrats!

If you want to learn more about this stuff, I highly recommend you pick up the following text:

Amazon.com: Engine Management: Advanced Tuning (9781932494426): Greg Banish:…

It really spells out all of the basics with some clear information on more advanced topics. It will help clarify what the scanguage is telling you.

Also, regarding fuel trims, note that there are most likely multiple trims --one associated with each cell in the fueling map (which you probably can't access) or at least a block of adjacent cells; cells are graphed by load (based on MAF value and known engine displacement) and RPM.

Short term trims (based on vacilations around 14.68 AFR / narrow band .5 volts) are averaged to create long term trims. One of those is probably carried into open loop (can Modshack confirm or refute that?)

The LTFT of +34 may or may not be a cause for concern. So long as driveability is fine, AFR's in WOT are fine, and the CEL light is off, it's not ideal, but acceptable (ideally, you'd want to have th ecar tuned so that these are all in the single digits and driveability is excellent).

Man, I can't wait to start playing with uprev on this car

+1 for that info! Thanks!! I might do an UpRev tune or get a Cobb Accessport one of these days.

Modshack · 06-18-2010, 06:22 PM

Quote:

Originally Posted by Jordo!

Also, regarding fuel trims, note that there are most likely multiple trims --one associated with each cell in the fueling map (which you probably can't access) or at least a block of adjacent cells; cells are graphed by load (based on MAF value and known engine displacement) and RPM.

Short term trims (based on vacilations around 14.68 AFR / narrow band .5 volts) are averaged to create long term trims. One of those is probably carried into open loop (can Modshack confirm or refute that?)

The LTFT of +34 may or may not be a cause for concern. So long as driveability is fine, AFR's in WOT are fine, and the CEL light is off, it's not ideal, but acceptable (ideally, you'd want to have th ecar tuned so that these are all in the single digits and driveability is excellent).

Man, I can't wait to start playing with uprev on this car

I don't know how sophisticated Uprev is, but when I had the HP tuners program for my LS3 corvette virtually every parameter in the areas of fuel, timing, temps etc was programmable by minute blocks within the program. The chart below is the high octane timing table. Each block can be manipulated. You also had MAF scaling which, in conjunction with the logging function and a wideband A/F gauge, allowed very precise tuning. It's my understanding that the Long term trim corrections are added to the WOT fuel map. This is why the reported A/F's (with the correct SG readings) are slightly rich...
Rich is better (and safer) than lean but doesn't make quite as much power which is why custom programming will show increases.

Jordo! · 06-18-2010, 06:56 PM

^^^ thanks for that.

It depnds on the application -- richer (say mid 11's to mid 12's) is usally a bit better for FI (especially if nonintercooled or intercooling isn't optimal or only lower octane fuels are available...), but really it all has to determined empirically on the dyno.

Just took a gander ant the UpRev site -- looks like they offer full datalogging (cipher) and have full control over all the maps... but I couldn't find confirmation that they can tune VVEL.

Is it really true that even the uprev software can't tune VVEL on our car??? That seems like a huge tuning limitation if true

Modshack · 06-18-2010, 10:12 PM

Quote:

Originally Posted by Jordo!

^^^ thanks for that.

It depnds on the application -- richer (say mid 11's to mid 12's) is usally a bit better for FI (especially if nonintercooled or intercooling isn't optimal or only lower octane fuels are available...), but really it all has to determined empirically on the dyno.

Just took a gander ant the UpRev site -- looks like they offer full datalogging (cipher) and have full control over all the maps... but I couldn't find confirmation that they can tune VVEL.

Is it really true that even the uprev software can't tune VVEL on our car??? That seems like a huge tuning limitation if true

No problem...My turbo cars run from 10.8 to 11.5 under boost. Forced induction always requires more fuel as it is used to cool the charge and reduce potential for detonation..
I make a boost controller for Audi's that lets the cars boost safely to 24psi with a chipped program enhancing the fuel and timing. Without the chip, 18psi is about max...

On the VVEL tuning I could see a lot of guys really screwing up their cars. Be careful what you wish for....

Jordo! · 06-18-2010, 10:55 PM

Quote:

Originally Posted by Modshack

No problem...My turbo cars run from 10.8 to 11.5 under boost. Forced induction always requires more fuel as it is used to cool the charge and reduce potential for detonation..
I make a boost controller for Audi's that lets the cars boost safely to 24psi with a chipped program enhancing the fuel and timing. Without the chip, 18psi is about max...

On the VVEL tuning I could see a lot of guys really screwing up their cars. Be careful what you wish for....

10.8! IMO, that's a tad rich unless you are stuck with 91 AKI (or maybe a little too high a CR on the pistons...). Were you getting det leaner than that?

Eh... I'm used to tuning VVTLi on my old 2ZZ S/C'd Celica... (with TWO piggybacks working in tandem no less!).

Having more lift points to play with sounds like a bit of a PITA, but as long as one can see the OEM map as a base, on the dyno it shouldn't take too long to determine whether adjustments improve things or not

It's just the intake cam that gets adjusted, right? Not both intake and exhaust -- or are both adjustable? (Okay, that would take a little more time to get right...)

Modshack · 06-19-2010, 08:08 AM

Quote:

Originally Posted by Jordo!

10.8! IMO, that's a tad rich unless you are stuck with 91 AKI (or maybe a little too high a CR on the pistons...). Were you getting det leaner than that?

Ah, but remember....24psi. Not so rich when dealing with those pressures!

Jordo! · 06-19-2010, 08:52 AM

Quote:

Originally Posted by Modshack

Ah, but remember....24psi. Not so rich when dealing with those pressures!

Well, fair enough -- epecially if this was a general tune intended to provide an extra margin of safety for folks who wouldn't be tweaking things on their own

What CR were you working with?

Modshack · 06-19-2010, 09:00 AM

Quote:

Originally Posted by Jordo!

What CR were you working with?

Stock Audi 225's run 9.5:1. on the 1.8T motor. Stock boost was 14 psi..

Audi/VW programming (Motronic)is a bit more complex and Detailed tweeking software is not generally available...We have to work around available chip programs (now flash programs)

1slow370 · 08-28-2010, 02:04 PM

just picked one of these up and and screwed around setting it up, and was gonna post how i did it then searched and now i'm pissed there was a guide. I think the best thing about this is that the front o2 sensors on our cars come from the factory as 5 volt lambda sensors so it should be fairly accurate. anybody know if you can datalog from a scan guage?

Modshack · 08-28-2010, 02:17 PM

No datalogging unfortunately.. but lots of good real-time info!

Jordo! · 08-28-2010, 05:04 PM

Quote:

Originally Posted by 1slow370

just picked one of these up and and screwed around setting it up, and was gonna post how i did it then searched and now i'm pissed there was a guide. I think the best thing about this is that the front o2 sensors on our cars come from the factory as 5 volt lambda sensors so it should be fairly accurate. anybody know if you can datalog from a scan guage?

Really -- we have factory wideband sensors? That's seriously bitchin

That should make tuning a snap (provided you can datalog it), and no need to spring for aftermarket widebands -- yay!!!

Some enable datalogging -- checkout the auterra system. I used to use that and it was able to read narrowband activity. so I don't see why it couldn't datalog the Z's wideband -- it's just another voltage input.

06-18-2010, 06:56 PM	#34 (permalink)
Jordo! A True Z Fanatic Join Date: May 2010 Location: nirvana Posts: 6,394 Drives: 2023 NATM Rep Power: 417	^^^ thanks for that. It depnds on the application -- richer (say mid 11's to mid 12's) is usally a bit better for FI (especially if nonintercooled or intercooling isn't optimal or only lower octane fuels are available...), but really it all has to determined empirically on the dyno. Just took a gander ant the UpRev site -- looks like they offer full datalogging (cipher) and have full control over all the maps... but I couldn't find confirmation that they can tune VVEL. Is it really true that even the uprev software can't tune VVEL on our car??? That seems like a huge tuning limitation if true __________________ Enjoy it. Destroy it. Last edited by Jordo!; 06-18-2010 at 06:59 PM.

08-28-2010, 02:04 PM	#40 (permalink)
1slow370 A True Z Fanatic Join Date: Aug 2009 Location: In the D Posts: 3,732 Drives: v8 74 260z ;) Rep Power: 7250	just picked one of these up and and screwed around setting it up, and was gonna post how i did it then searched and now i'm pissed there was a guide. I think the best thing about this is that the front o2 sensors on our cars come from the factory as 5 volt lambda sensors so it should be fairly accurate. anybody know if you can datalog from a scan guage? __________________ ANSWER PRICE LIST Answers - - - - - - - - - - - - - - - - $0.75 Answers (requiring thought) - - - - $1.25 Answers (correct) - - - - - - - - - - $12.50

08-28-2010, 02:17 PM	#41 (permalink)
Modshack A True Z Fanatic Join Date: Mar 2009 Location: Greenville NC Posts: 2,883 Drives: 370Z Sport Rep Power: 976	No datalogging unfortunately.. but lots of good real-time info! __________________ Steal my car! (SOLD)...Now Porsche Cayman S Oil Cooler DIY: Here!

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