Small throttle openings light switch ...How does your's feel?

[coreytrevor]

I figured if anyone knew exactly how it works it would be Meinolf.

[Meinolf]

Hi,

 

CO trim adds or subtracts a constant time per value to the overall injector pulse duration. The time is the same across all throttle (TPS) settings and rpms.

 

((Fuel Map value x Fuel map value factor) + (CO trim value x CO trim value factor)) x trim factor_airtemp x trim factor_enginetemp x trim factor_airpressure x trimfactor_{batteryvoltage} x trim factor_n = injector pulse width

 

Hence the influence on AFR depends on the Fuel map value and CO trim value;

- At idle the fuel map value might be 50, corresponding to 3200µs injector pulse width (50 x 64µs). A CO trim value of 50 equals 320µs (=50 x 6,4µs), which is 320 / 3200=0.1%.

- At WOT the fuel map value might be 200, corresponding to 12.800µs injector pulse width (200 x 64µs). A same CO trim value would then amount to 1/4th (320 / 12.800 = 0.025%).

 

Consider the CO trim to be the electronic equivalent of the bypass screw openings. Opening the bypass screw will allow more air to be mixed to the air/fuel mixture, the percentage of which diminishes when the air flow through the throttle increases. Both methods are useful ONLY to adjust AFR/CO at one specific loadpoint. CO trim affects both cylinders, the bypass screws each cylinder respectively. An additional problem of the bypass screws is that the setting is difficult to duplicate. How exact is 1/2 turn being duplicated on a different bike?

 

A neater way to get to targeted AFRs at specific loadpoints is to measure AFR at those points and adjust the fuel map values accordingly.

 

Cheers

Meinolf