What controls MAF airflow on scanner?

I'll keep it short.

Been logging my LS3 swapped Transam car for awhile now, and with an average AFR of 12.45 across the board, I see a peak of 56 lbs/min in the higher rpms. For grins, I richened up the fuel trims via MAF frequency and changed my target AFR to 11.7, and according to my MAF airflow and also dynamic airflow, the car has picked up power. The richer I make it via tuning the MAF frequency, it continues to make power. I haven't richened it up past 11.4 or so because that seems ridiculous, but the car seems to just eat it. How does the computer calculate its airflow numbers? If I change the values in my MAF frequency table, does this cause my airflow numbers to go up?

I'm confused, thanks.

Alex

You are calibrating the MAF to make it richer. That means you are telling it for a certain frequency you are getting more air. It isn't actually reporting more air.

Look at the Hz as you changed the AFR (which the right way is through the PE if you want it richer). I would assume going that rich your max frequency actually dropped, indicating LESS airflow, assuming you are NA. It is possible the frequency went up, but being that rich if you are NA I would assume it was because something else was off (like too much timing and now it just isn't pulling as much).

Tune your MAF with a WB to meet the commanded fueling and then tweak the PE to get the commanded AFR you want.

Thanks for the insight. Surprisingly, my MAF frequency has gone up when going from .86 lambda to .80, from around 10750 hz to 10875? I believe I have seen even as high as the low 11000s in the past. Timing set to 25 degrees all in at WOT, bumping it up didnt change much. Just looking for a reliable variable to measure to see if Im making any more.power. Any advice? I will try adjusting PE, what I have been doing is altering my EQ commanded, and then adjusting my MAf frequency according to my EQ error vs frequency.

Anyone? :)

I would overlay your speed graphs in Excel. Hard to believe an NA car makes good power in low 11’s AFR.

Post up some logs too if you can

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Originally Posted by WS6FirebirdTA00

Post up some logs too if you can

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Will do. What do you mean by overlaying the speed graphs in excel? Would love to learn

Download virtual dyno.
that can then use your logs and turn it into a dyno graph. Assuming you do your runs on the same bit of road it works out very good for comparison when tuning.

I typically will export to Excel and overlap data from runs. You can look at speed vs. time as long as the road and conditions are the same and see which accelerates faster. You can also create a custom PID for acceleration rate for more on the fly monitoring. You aren't going to see small changes, but it may help.

WS6Firebird, heres a good scanner log from earlier with quite a few WOT runs targeting .83 lambda with a 14.63 stoich ratio. That comes out to 12.2 across the board. I have it very close, it dips rich a few times and I just adjusted MAF frequency for suit. Now I see around 53-54 LB/MIN on the scanner, which may be a tad low for my setup. Let me know what you think!

Scanner log and tune file. I have since updated my MAF frequency and changed idle spark a little bit.

Where is your WB? B1 and B2 have drastically different mV readings at WOT, curious if they are both hooked up. If they are, swap WB from one bank to the other to see. It is possible one side is running quite lean and that could by why more fuel is helping.

I also like to disable LTFT.

WB should be labeled at the very bottom "MPVI equivalence ratio" or something like that. You know, ive noticed the same thing. B2 is a brand new sensor, but I have it in the downstream 02 spot. B1 is in the correct upstream spot. The WB 02 is in the upstream spot on the passenger side. What would cause such a variation? The location of the 02, the age of the 02, or an intake manifold leak? I see 97-99 kpa at WOT, couldnt imagine a gross leak.

I wonder if it could be exhaust leak or something?

Try to switch the WB over to the other side and see if you get similar results. I still question going that rich, unless the WB is off. Just seems like a lot.