FUEL CONTROL

A speed density algorithm is used to calculate the fuel injection pulsewidth. The temperature used is called the “In Cylinder Temperature” which is calculated as being somewhere between the coolant temperature and the air temperature, depending on the air flowrate. However, this may not be perfect for the engine configuration when combined with the “warm up” and “start up” fuel multipliers, and thus the below adjustments are provided to fine tune the system at various temperatures. The speed density calculation does not apply when the engine is Cranking (speed below about 450 RPM). After combustion starts and the speed picks up above about 500 RPM, the engine begins the speed density calculation, along with the “Warm Up” and “Afterstart” fuel. Warm Up fuel is using a default table (more enrichment at colder engine) that can be tweaked here if needed – warm up fuel works at all operating conditions above cranking, but is 0 at a fully warm engine. Afterstart fuel enrichment has the special purpose of building the wall fuel films in manifold and cylinder is decreased with the number of revolutions as the film builds and the parts warm up rapidly – most of Afterstart fuel is gone within about 800 revolutions. The adjustments provided here can help fine tune it to the particular application.

Fuel -20F Cyl = This affects all of the fuel at this In-Cylinder temperature, except the cranking fuel.
Fuel 5F Cyl = This affects all of the fuel at this In-Cylinder temperature, except the cranking fuel.
Fuel 32F Cyl = This affects all of the fuel at this In-Cylinder temperature, except the cranking fuel.
Fuel 70F Cyl = This affects all of the fuel at this In-Cylinder temperature, except the cranking fuel.
Fuel 85F Cyl = This affects all of the fuel at this In-Cylinder temperature, except the cranking fuel.
Fuel 105F Cyl = This affects all of the fuel at this In-Cylinder temperature, except the cranking fuel.
Fuel 130F Cyl = This affects all of the fuel at this In-Cylinder temperature, except the cranking fuel.
Fuel 195F Cyl = This affects all of the fuel at this In-Cylinder temperature, except the cranking fuel.
Afterstart 20F = This affects the fuel at this Coolant Temperature, just after cranking, and lasts for just a few seconds.
Afterstart 65F = This affects the fuel at this Coolant Temperature, just after cranking, and lasts for just a few seconds.
Afterstart 170F = This affects the fuel at this Coolant Temperature, just after cranking, and lasts for just a few seconds.
Warmup 20F = This affects all of the fuel at this Coolant Temperature, except the cranking fuel.
Warmup 65F = This affects all of the fuel at this Coolant Temperature, except the cranking fuel.

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