Accel Fuel

Question :
How does the Async fuel factor come in to play, this is per throttle site and an exponentially curving slope. I am really tempted to play with this (increasing it) but wanted to check in with you first.

Answer :
The chances are your AFR will read lean. You do have to be a bit careful because if you make the mixture too rich, the AFR will read lean again because the fuel will not burn correctly if the spark is put out and then you will have excess oxygen showing a lean AFR again. Slowly increasing the value as you have done is the correct way to do it. As you experiment further you may find certain areas e.g. speed sites require extra fuel, the Async Accel Pulse Width map is actually temperature vs speed, not throttle vs speed.

The other map you have found the Async Accel Fuel Factor, which shows an exponential curve is actually the rate of throttle change, the column running down the left shows the percentage of fuel that will be added to the overall fuel pulse width. This basically takes the value you have in your Async Accel Pulse Width map and then applies the percentage from the Async Accel Fuel Factor e.g. if the map has 10% whatever the map ‘TPS vs Speed Fuel Map’ has let’s say 10ms so for example 10% of 10ms is 1ms, then depending on the rate of throttle change would depend on the percentage of the 1ms that is added to the overall fuel pulse width. If the throttle is moved extremely fast, it will look at the right-hand end of the Async Accel Fuel Factor map which says 100% currently and therefore 1ms will be added. If the throttle is not moving at all, then the left-hand end of the map is accessed and the percentage is zero so therefore no fuel is added. If the throttle is moved at a rate between these 2 points, then the fuel quantity would depend on the percentage applied. Although you can modify the Async Accel Factor it is normally best to modify the pulse width of Async Accel Pulse Width map as this is easier to understand and simpler to experiment with as each engine will vary. If you then wish to experiment later with the Async Accel Fuel Factor, do so after you have experimented and understand what effect you can achieve with the information described above.

Please take great care when modifying the Async Accel Factor map.