ba2600 Big Air SCT Transfer Function Question

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bamaFoxJuan
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Posts: 65
Joined: Fri May 26, 2017 8:36 pm

ba2600 Big Air SCT Transfer Function Question

Post by bamaFoxJuan » Sat Jun 10, 2017 1:15 pm

Hello, I am having trouble dialing in my car to my liking.

Combo is:
Big Air 2600
xl3v-a9a 42 lb injectors that came in a Ford Racing box.
302 afr 165 heads

I recently read the sct chip on my 93 fox mustang that was tuned many years ago. The transfer function looks to be closer to a 2800 maf than a 2600. It actually flows more than a 2800 past 4.5 volts. Does anyone know if the function has changed that much over the years?

Problem I have is, when I type in the injector data correctly, it is very lean with a ba2600 curve. It actually runs a lot closer with the 2800 curve. I can get the car to run fine. I want to do it right though, before i put my supercharger back on.

Combo is:
Big Air 2600
42 lb injectors that came in a Ford Racing box.
302 afr 165 heads
Last edited by bamaFoxJuan on Sat Jun 10, 2017 4:05 pm, edited 3 times in total.

bamaFoxJuan
Regular
Posts: 65
Joined: Fri May 26, 2017 8:36 pm

Re: ba2600 Big Air SCT Transfer Function Question

Post by bamaFoxJuan » Sat Jun 10, 2017 1:21 pm

I guess I should add that I am using the injector data that matches what I found online and the original tune. I don't remember if they came with a transfer function sheet or not. The meter is also a ba2600 that I got from a sct dealer that tuned my car. I figured his curve was right but, it is like a 600kg/hr difference in the transfer function between the chip and what I find online for the ba2600.

All of these parts were purchased years ago. Probably about 2012 or so.


So here is what I did after I re-checked the injector data by decipha's site.

I took the simplified ba2600 curve from decipha site and then multiplied it by 1.25. I made a wot pass in 3rd gear from 14 mph to 90 mph. I targeted a 12.5 afr. It hit the 11's when I first lugged it from a very slow roll. After that, it never left the 12s. Obviously, the yellow line is the afr line with the column on the left showing 12 on that grey line it rides through the rpms.

Image

yellow = afr (which is on the 12 line that got cut off)
red = tp
white = mafv
green = timing
dark green = mph

bamaFoxJuan
Regular
Posts: 65
Joined: Fri May 26, 2017 8:36 pm

Re: ba2600 Big Air SCT Transfer Function Question

Post by bamaFoxJuan » Sat Jun 10, 2017 6:59 pm

Also, I don't want to seem over meticulous over this. I actually tried the simplified curve after I made the thread and it just worked out that good after two other guesses.

I didn't notice that my idle and part throttle were rich. I moved the low slope up to 55 and it is now perfect at idle and part throttle. I'm putting the charger back on tomorrow.

...Now I don't even car that my maf supposedly reads that it is good for more horsepower than advertised. I won't see it with this set-up anyways.

LeadHead
Tuning Addict
Posts: 595
Joined: Tue Nov 02, 2010 10:27 am

Re: ba2600 Big Air SCT Transfer Function Question

Post by LeadHead » Thu Jun 22, 2017 9:14 pm

As long as it runs well and your AFR matches your LAMBSE, it really doesn't matter what the curve ends up being. These aftermarket products don't have the same kind of quality control OEM stuff does.

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