question about AFC's

[Dave H]

I have been tuning domestic stuff for years, have many championships and wins in various types of racing to my credit, but now I am playing around with some import stuff. I have Hondata down pat (S300 and Kpro), along with most other stand-alone management systems, but I have a question about the AFC's (such as the neo).

I understand that all you are really doing with these is skewing the map reading the computer see's to correct A/F ratio, but if you have to go negative on the AFC, doesn't the lower map signal coming from the AFC to the computer effect timing as well? If you have to take 20% out on the AFC to correct for larger injectors, doesn't the computer see a 20% loss of map, which would cause the computer to add a bunch of timing since the timing map of the computer at 20% loss of map is much higher?

If you look at hondata, and pull up the stock timing tables, there is a 6-8 degree difference between 100kpa and 80 kpa (a 20% loss). That would mean that you would be running as much as 8 degree's additional timing at WOT than you should.

Am I missing something, or have something confused?

Thanks

Dave

[Relic1]

that is the very reason why VAFCs kill engines.
There are way to many programs out there that edit the honda ECU's programming to even consider strapping a AFC of any sort into a honda.
As far as in other manufacturer's cars, a little change is all I'd do. Any resizing of injectors or serious changes and you're asking for short engine life.

[Dave H]

Thank you for confirming Relic, I just wanted to make sure I was thinking straight.

-Dave

[Relic1]

you're on the right track.

BTW - http://forum.pgmfi.org/index.php is a great tuning source if you haven't all ready found it. (searching on there is really important and valuable)

[SOHC_MShue]

Yep I stay away from afcs like the plague. Nothing but trouble there.