potatobbq

Is there any way to observe this self learning function? The boost setting sectin of the FC Commander states: "By utilizing a self learning function, ideal boost response and stability is achieved for that particular car." So how exactly do you know when or what the PowerFC is learning? You can manually alter the boost pressure and base duty settings, but when the PowerFC has "self learned" optimal settings, will those settings be reflected at all in the display? For example, if you alter the base duty setting to 50% and the PowerFC learns that 52% is optimal, will the display actually change to 52% automatically?

adax

iTrader: (2)

Attache is a previous post that does not completely answer your question but may help.

posted April 19, 2001 02:50 PM

I decided to run a little experiment, and I think I have answered my own
question. I think the PFC is smart enough to reduce boost, or at least try, if
your duty cycles are too high. Here's what I did:

I set the duty cycles to be identical on the two boost programs; 68% primary
and 72% secondary on both programs 1 and 2. I then set the boost level on the
first program to 0.85 (both primary and secondary). The second program I set
both turbos to 0.65. Then I started making boost runs in all gears.

For clarification, the commander screen looked something like this:

1. Pr 0.85kg/cm2 68%

Sc 0.85kg/cm2 72%

2. Pr 0.65kg/cm2 68%

Sc 0.65kg/cm2 72%

Results:

When the PFC was set to program 1 (0.85), I made peak boost of about 0.75 in
all gears except 5th, where I slowly creeped up to about 0.85.

When I set the PFC to program 2 (0.65), peak boost in all gears was about
0.66.

I then went back to program 1 and started to increase my duty cylces until I
made ~0.83 in the lower gears. Retesting in 5th, I was still making about 0.85.

From this info, here is my new theory of how the PFC controls boost:

1)The set point not only determines where fuel cut will occur, but what boost
level the PFC "shoots for".

2)The duty cycle gives the PFC a starting point to work with. The PFC then
adjusts beyond that duty cycle (up or down) to achive the boost set point.

2a)If the duty cycle is too low, you'll make less boost than the set point. In
higher gears (when the PFC has more time to adjust) you'll slowly creep toward
your set point.

2b)If the duty cycle is too high, then the PFC cuts back on the duty cycle when
you reach your set point. If your duty cycle is REALLY high, you could possibly
overshoot your set point. The PFC will probably try to bring the boost back
down, but depending on how high the duty cycle is, it may never be successful.

How does this sound? Anyone have experiences that would suggest this model
is incorrect?

Eric

spyfish007

Very good acurate write up .... it works just like the AVC-R except without duty cycle per rpm. You will notice that the PowerFC has a very difficult time controlling boost if the duty and target values are way off. Once again good write up.

potatobbq

Thanks, I think I now have a better overall idea of how the PowerFC actually controls boost.