MAF AFR error

[Turbomustang93]

Can someone help me out on making a AFR error table for Ford . I have done this several times on GM stuff but I cannot get it nailed down on this ford stuff . im working on a 2013 mustang

[Thatwhite5.0]

Create a histogram including MAF Period vs STFT Avg.
Disable LTFT.
Take results and multiply by percent.
You can drive around or slowly rev the engine to get a good stft to multiply to the whole table. Then drive around to get fuel trims more on point

[metroplex]

Create a histogram including MAF Period vs STFT Avg.
Disable LTFT.
Take results and multiply by percent.
You can drive around or slowly rev the engine to get a good stft to multiply to the whole table. Then drive around to get fuel trims more on point

I actually use STFT+LTFT. I don't disable anything (from memory: i shut off WOT open loop and retard timing, so I can go WOT in closed loop and monitor STFT for WOT). I did this with the older Fords that didn't have wideband O2s like the newer Fords, and compared it with an actual Innovate wideband. Results were spot-on, even at WOT.

I also use STFT+LTFT on the Cobalt SS Turbo, which does have a factory wideband O2.

[CCS86]

I would also advise to disable LTFTs. In my experience they apply corrections too broadly and you will have situations where LTFTs are adding and STFTs are subtracting. This actually increases the lag time to get correct AFR.

On a car where you plan to fine tune your individual combo for best fuel trims, I would just leave LTFT disabled. I see them as a way the MFG can get away with one tune applied to many cars. If there is really a long term trend of fueling error, you should be able to fix it yourself.

I would also advise against creating that chart, doing a long drive and using those results to "correct" the MAF transfer function. You will be including all kinds of transient fueling effects in there, unrelated to the MAF sensor calibration.

I have been tuning my car for a couple months now and still haven't even touched the MAF transfer function. I have improved fueling with injector settings, transient fuel tables, speed density tables, temp comps, etc. You have to ask yourself, "why would my transfer function be way off?". If the MAF housing and everything upstream of it are stock, the transfer function should be very close. Making big adjustments to the transfer function lies to the ECU about how much air is going into the engine, which causes other forms of error.

[Turbomustang93]

ok thanks for the responses I was hoping there was a way to use the factory wide band with the AFR error . I will use the fuel trims then it will get the same result . thanks .

[CCS86]

ok thanks for the responses I was hoping there was a way to use the factory wide band with the AFR error . I will use the fuel trims then it will get the same result . thanks .

One reason you don't want to tune with a calculated AFR error, is that it doesn't take into account O2 Transport delay. The current reading of an O2 sensor (and the calculated AFR error from it) is a result from an injection even that happened in the past. That delay depends on load and RPM. STFTs already take into account the transport delay, so you will get a more accurate correction.

[C0LD ZER0]

so depending on fuel trim better than AFR gauge ? my teacher in tuning he told me without AFR we can't tune , then we tune like blind !

[veeefour]

so depending on fuel trim better than AFR gauge ? my teacher in tuning he told me without AFR we can't tune , then we tune like blind !

You can't but that only applies to 99 Chevy or something similar. Those modern cars have 2 widebands stock so you don't need anything else besides knowledge.