Air fuel code for scangauge
 

I have been trying multiple codes for the Scangauge II, so I can measure my A/F ratio, but had no success. Has anyone had any luck getting the Scangauge II to display the A/F ratio. I tried Google but no luck.

Someone here claims to have done it, but I followed his info and could not get it to work on mine, and I've done a fair amount of SG code entry...

That was me. I used the "Alternate A/F Ration (general)" setting for CANSF. See page 3 in the XGauge list: http://www.scangauge.com/support/pdfs/XGAUGE.pdf

It works on mine, I do get an A/F reading. It normally is between 13.7 and 14.7. These look like fairly normal A/F ratio's (rich to stoichiometric) so I assume this means this setting works correctly on my Scangauge.

I'll try that setting and report back in a few. I see you are rooting for Holland - I like! :rock:

+1 for you JB1 - it worked. Shows me an A/F of 14.5. Is that good, bad or ugly?

Edit: I did a quick highway run and the A/F ration varies from 0 (downhill no accelerator pushed) to 17.5% at full throttle, but most of the time is around 14.5%. So I guess the 17.5% is quite lean. Not sure if that is normal.

Normal A/F will remain in the 14.5 to 14.7 range as long as you're in closed loop (partial throttle mode). When you cross over to open loop (WOT), mixtures should go rich not lean. YOu can set the Scangauge to show the transition. If that 17.5 is accurate it is dangerously lean. Ideal full throttle A/F should be in the 12.5-13% range.

I'm glad to know this worked out. When I get around to doing any mods to my car I plan on buying this! :tup:

And please check your A/F ratio! It would pain me to see someone on the forum grenade their engine from being too lean.

Thanks for the rep. I'm Dutch so yeah, go Holland! I hope this will finally be our year :tup:

I just noticed your custom title, funny, I'm about to order a set of "DUTCHZ" vanity plates, I bet it will add at least 50hp :rolleyes:

:icon18: Yeah I felt the difference as soon as I put my plate on!

I'll be monitoring it closely - tonight on my way home i will floor it a couple of times and re-check the A/F ratio. Wonder why that would happen though...I put the stock intakes back on, which would presumably give me less air and a lower A/F ratio - correct me if I'm wrong. But then again, doesn't the ECU compensate for that automatically? I guess that when in you are in open loop everything the ECU does is out the door and it is max fuel and whatever air she can breath.

The ECU does not compensate for Intakes, so when you had the R2C's on it will not compensate I believe because of the different size tubing and all that MAF mumbo jumbo. Someone else can answer that better than me because I'm not expert.

Why did you put the stock intakes back on? Because of the a/f ratio or something else? I had Takeda intakes for a while but got rid of them because of the high air intake temps. (sound was great though). If I remeber correctly, a/f ratio with the Takedas was mostly in the 13 range, so rich not lean.

The reason I took them out and put the stock back in is that I wanted to see the difference in air intake temps. Also I will be doing another dyno run in the next few weeks with the stock intake and maybe I'll do it also with the HKS Super Hybrid drop-ins I ordered. I might also order the Cobb post MAF hose as well - not sure yet. I know some folks wanted me to throw the R2Cs back on after I dyno with the base intakes, but not sure if i can make that all happen. In all honesty - I have not noticed much of a difference, if any. The intake temps with the R2Cs installed while cruising at highway speeds were about 6-8 above ambient - same results with the stock intakes. The main difference is that the intake temps while stopped, do not climb as fast with the stock intakes - they also fall faster with the stock set-up. I did not have the code to measure the A/F ratio with the R2Cs, so not sure what it was before, but only WOT I measure now 17.5-18.1 A/F ratio, which scares me a little.... Not sure why the car would run so lean with the stock intake. Maybe it has something to do with the HFC and CBE I have...

Well, for what it's worth, until 3 weeks ago I had Berk HFC + Berk CBE and stock intake with Cobb post MAF hoses. As far as I know I never saw the A/F ratio go over 14.7. Since then I swapped the Berk HFC's for the stock cats and the A/F ratio remained the same. But I'll pay more attention tomorrow during my drive to work to see what the A/F ratio does during WOT. I'll report back later!

Is that a transformed value derived from the narrowband O2 voltage? In closed loop, all the ECU cares about is seeing the O2 hover around .5 volts (i.e., ~14.68 AFR / lambda = 1.0).

There's pretty much no way it can run too rich or too lean in closed loop (fuel trims will correct) unless something is really fvcked up, in which case you'll get a CEL.

In open loop the AFR will be whatever was tuned from the factory without the narrowband commanding any adjustments (except probably for a long term trim that carries over that is).

Say what? Is that a sustained AFR or only an occasional blip (e.g., going lean on tip-in)?

If you are seeing stable AFR's that lean under heavy load (i.e., WOT, high RPM's) GET OFF THE THROTTLE! You may very well get massive detonation and kill a piston or spin a bearing in short order.

Assuming that value is accurate -- best to confirm with a good wideband O2 either on a dyno or one you can buy (e.g., AEM UEGO)

You do not want to see anything leaner than ~13.5 under heavy load, N/A and a bit richer would be preferred for best power.

Especially if you are using 91 AKI instead of 93... with 93 anything south of stoich is probably okay (N/A), though not best for safety or power.

Prolly going to get an UpRev tune here at Forged within the next few weeks - that should fix it. Just curious if JB1 runs lean at WOT as well. The car must have been factory tuned pretty lean to begin with and with any bolt-ons will run too lean at WOT. I recommend that anyone with bolt-ons should get their WOT A/F ratio checked.

I couldn't play around too much this morning, construction and busy traffic doesn't mix well with WOT driving... But I did get to try it out a couple of times and the A/F ratio was steady at 17.5 during WOT. I mostly tried it in high gear/low speed situations, as this offered me the chance of having a WOT without accelerating into the car in front of me to quickly.

I feel like the 17.5 is some sort of a default value, as it didn't seem to change at all as long as I had the accelerator floored. Also, as soon as I lifted just a little, the reading went back below 14.7

But I'm not sure yet, so I will try it out some more tonight and this weekend to see if that 17.5 is indeed a default value during WOT or if it changes.

Too bad I didn't look at the A/F ratio during WOT driving when I still had the Takeda intakes and HFC's. But then again, I normally have my eyes on the road during WOT driving :)

I did some WOT driving this morning and got the same results. It is not just a blimp up to 17.5, but 17.5 steady at WOT.

Modshack - were you able to get the A/F code working on your Scangauge? If so, could you possibly test your A/F ratio at WOT?

Yeah...Just went out for a run and it's working. As I and Jordo have pointed out, I think you have a problem...

With my Long term trims at 0%, and the scangauge set to show open loop/closed loop transition, and Sensor 1, Bank 1 selected I am getting the following:

Closed loop: Normal 14.1-14.7 reading

Open loop: 12.0:1 to 13.2:1 at the point it transitions to open loop. Numbers seem to depend on gear and RPM's when I go WOT. These are numbers I would expect.

My current tune: stock Airboxes and a Stillen Exhaust. It is my understanding that the front 02's are 0-5V. Wideband sensors so this should be pretty accurate..

Since this ratio is fixed, and not manipulated by 02's or MAF's at WOT, you may have a correctable problem. I would check for any Vac leaks, particularly where the PCV hoses connect to the post MAF tube. You've had these in and out so there may be something loose.

The other variable is your HFC's.....though Dyno runs have not shown these to run particularly different from stock.

Check to see that you've programmed for sensor 1 on either bank 1 or 2. These are the front 02 sensors and the ones that most accurately measure A/F ratioos.

Good luck tracking this down. In the interim, I'd stay out of WOT operation..:tup:

Modshack - to clarify: were you able to get an A/F ratio measurement on Sensor 1, Bank 1 on the Scangauge? Or on the Alternate A/F Ration (general)" setting for CANSF? Or are you referring to the Long Term Trim on Sensor 1, Bank 1?

Another question: How long does it take for the long term fuel trim to be accurate? I just coded my Scangauge to measure the LTF on bank 1 and it says 34 at idle. Is that number derived from a few days of driving, or just since I coded the Scangauge? Did hose check - looks fine.

I am measuring the regular A/F ratio...Bank 1 sensor 1....The first Code line in that CANSF category. On trims, the Programming I am using is left over from when I had this on my corvette: Fuel trims for CANXX vehicles, long term trim bank 1 on page 1

Thanks Mod - gonna try right now. Maybe that is the issue.

Sounds like it could be...Let us know!

And you should get instant reading on long term trims...That data is built up in eproms and retained. a few Percentage points + or - 0% is where it needs to be..

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?!

OK...Good! JB1 needs to fix his too..

On the LTF's, I just checked the coding on mine and it is on page 1, CANXX, TXD 07E00107 Yada yada. Double check your entries..

Transposed the 9 and the C. LTF trim is now -11, but I will have to do some driving. Off to the pool now for a quick dip. Thanks Modshack (+1) and JB1. This is a great forum with some great members!!

Great...Thanks!

-11% (rich correction) is what I seem to recall from my car when it was essentially stock. This is what got me going on the MAF tube experiments.
Remember, this is a "correction" and does not essentially mean your car is running rich. The 02 sensor reads the mix and sends appropriate signals to the ECU to correct the numbers to Stochiometric (14.7) through injector duration changes. It's a correction factor based on the results of the stock tune and flow. Watch the short term trims as well to see the instantaneous corrections. LTF's are built up over time. To clear them to 0, unhook the negative battery lead for a few minutes, and the adaptation will start anew..

http://images51.fotki.com/v747/photo...ueltrim-vi.jpg

Done! Thanks a lot Modshack!

I switched to the Bank 1 / Sensor 1 setting and It now shows a "proper" rich ratio of around 12~13:1 on open loop Opperation. So I guess the "general" setting is not the right one for our cars and that 17.5:1 reading in the "general" setting is indeed some kind of default. BTW, my long term fuel trim shows -8

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 :excited:

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

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.

http://images36.fotki.com/v1183/phot...anehigh-vi.jpg

^^^ 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....;)

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...)

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?

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)

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?