Air fuel code for scangauge

JvKintheUSA

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.

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JB1

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

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JvKintheUSA

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.

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JvKintheUSA

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?

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Modshack

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..

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JvKintheUSA

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?

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JvKintheUSA

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.

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Modshack

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

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JvKintheUSA

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

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Modshack

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..

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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?!

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Modshack

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..

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JvKintheUSA

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!!

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Modshack

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..

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JB1

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

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Black Fangs // Black rear Valance // Berk CBE // COBB post MAF tubes // K&N drop in filters // Setrab Oil Cooler // Stillen Sway bars // Z1 SS brake lines // Stillen brake cooling kit // Harness bar //