My new bike I'm picking up on Tuesday (2012 honda shadow phantom) has cobra exhaust and also comes with a power commander installed, I was just curious in lamens terms what the power commander does
Following is a straight copy of what I've posted before, is not quite a direct answer to your good question, but does deal with it while also going a bit beyond. One ought also to have an understanding of synching and the need for it, and not just the PC alone.
I hope this helps you along.
Synch the PC III to the T P first.
Think of it this way.
The basic map is in the ECU which the T P is connected to.
The PCIII is a piggy back device.
It does not hold a map, and instead holds a map adjustment.
So when your ECU is ready to send a pulse width signal to the fuel injectors, the PCIII makes a small adjustment to the pulse width signal.
The ECU map is a co-ordinate map based on a matrix of % Throttle Opening X RPM.
The PCIII adjustment is written into a matching co-ordinate map.
Now think of the two maps as two grids that have to be perfectly aligned with one another, just like two pieces of graph paper stacked so the lines are exactly matched.
When you synch the PCIII to the T P, it's just like the graph paper analogy I described above.
To give you an idea of what can happen if you don't, here is a real world example. Engine at 2 % throttle opening, RPM @ 1500. PCIII Closed Throttle Position error of + 3 %. What happens is that the PCIII will alter the ECU 2 % x 1500 RPM output with a 5 % x 1500 RPM based pulse width adjustment, and the fueling will be wrong for the actual engine condition.
My 919 was out 2 %.
My son's 600 GSXR was out 5 % !