AFC Hack and timing issues

[Likklekilla]

I have read a million and one post all over about running the AFc hack and it advancing the timing and so on. I would like someone to give a "baby" type explanation of why this happens and how it can be corrected when using AFC hack and larger injectors.

Another thing is, when using a BTM and this setup yes i know the BTM only affect on boost timing, but i was thing the RPM range at which ur not on boost, how advance is the timing, and would it be such a severe advanced timing such that u could cause damage at rpms below 3000?

Wat can u do to solve that issue?

some say dont use AFC hack over say, 12 psi.
Question: When going over 12 psi wat other parameters play an important role when tuning a motor other than (fuel and timing) that u need to have control over that the car itself cannot control?

[pitchblacktyper]

i forsee oscar saying something about this..... :hijacked: lol j/k

[konigcivic]

from what i hear the afc advances the timing some.. if you are really worried about it just use your msd btm to retard under boost then retard your base timing a few degrees untill you get it dyno tuned then let the pros do it..

from what i was reading you cant use the hack over 10 or 11 psi cause the stock map sensor wont read above that level. something about the voltage of the sensor will go over 3 volts which the computer wont handle it and throw a check engine light.. anything over that psi you should get a new computer anyway like hondata or some other programable computer so you or your dyno guy can tune every aspect of your motor...

later..

[TurboEF9]

I can explain why it happens...

[short version]

Your entire table width is kept between 0-3.1v (~26inHg to 1.3psi). The AFC allows for the use of the entire spectrum (0-5v) of the MAP sensor by scaling down the signal to fit between the accepted 0-3v check of the ECU. If you look at the pics I made it'll show you the stock ignition table of the PM6. Less pressure, more advance, more pressure more retard. Note in the pictures where 3.0v crossover from vacuum to boost is in the unscaled ignition map, vs the scaled. This shifting of the crossover point because of the scaled use of the full voltage spectrum is why your timing indirectly gets, "advanced". (Keep in mind the "why don't you just change the values?" statement doesn't work here because if you're using the AFC hack, you typically don't your ECU chiped to modify the ignition table) Have a look..

This is a stock PM6 ignition table.. without scaling with the AFC. Try to understand that 0-3v is Vacuum (from the MAP sensor).
http://index.driftkids.com/0-3Vacuum.jpg

Apply that same concept to the full spectrum scaling of the AFC (0-5v)
http://index.driftkids.com/0-5All.jpg

Take for example in the first picture (the stock MAP sensor signal) 9 inHg at 500 rpms yields 9.36 degress BTDC. In the second picture (the AFC modified MAP sensor signal) the 9 inHg column has "moved". But the actual values in the map didn't move, so now, you're 9inHg at 500 rpms yields 18.00 degrees BTDC!! ...there is your advance. :D

..does that help you understand?

[Likklekilla]

yes thank u very much turbo understand now!

[FMYStreetRacer]

hey if needed could you burn me a chip like that?