CRANKING FUEL

The fuel requirements during cranking are very far from the speed density calculated amount. Thus, the fuel is not using that equation during the time between stall and about 450 RPM. The main factor determining the amount of fuel needed is the engine temperature (very cold requires several times as much fuel as a warm engine), as the fuel wall film needs to be applied, and the cold engine parts will cause most of the fuel to cling to them as a liquid, and not take part in the in-cylinder combustion. The various intake manifolds and engine sizes are also going to affect the amount of fuel required. In order to help the engine start much more quickly, the system also injects a large squirt “Prime Shot” from all of the injectors a few moments after the key is turned on. If the prime shot is not desired, such as if just the radio is to be turned on – pressing the throttle fully open prior to and while the key is turned on and while the fuel pump primes, will cause the Prime Shot to be cancelled.

Prime Fuel Mult = The prime injection will fire the injectors after key on to help make starting much quicker.
Crank Open TPS Mult = If the throttle is opened above this (and below about 50% for clearing flooded engines), the fuel injection is increased. This is to help start the car if the calibration is not yet finalized for starting. Also, the open throttle lets in much more air than just a closed throttle, so the extra fuel is sometimes needed to balance the extra air to deliver a burnable mixture to the cylinders.
Prime Shot Delay = If the engine is not cranked directly after key on, the software will wait a few seconds before injecting the Prime Fuel to allow time for the fuel pump to purge the throttle body of vapors, and get full fuel pressure to the injectors.
Prime Crank Revs = If the engine is cranked directly after key on, the software will wait a few revolutions to allow time for the fuel pump to purge the throttle body of vapors, and get full fuel pressure to the injectors.
CRANK IAC Mult = The IAC is opened an extra amount during cranking to allow more air into the engine for faster starting, and extra torque to spin the engine against thicker cooler oil. Adjust this to get good starting without excessive overshooting after starting.
Crank Fuel 20F = At cold engines, the default calibration increases the fuel injected by a very large amount. However, different engines and manifolds will show different needs. Adjust this to get good starting response.
Crank Fuel 65F = At cold engines, the default calibration increases the fuel injected by a large amount, however, different engines and manifolds will show different needs. Adjust this to get good starting response.
Crank Fuel 170F = At warm engines, the default calibration decreases the fuel injected by a large amount. However, different engines and manifolds will show different needs. Adjust this to get good starting response.
Afterstart 20F = This is the exact same value that is found in the Fuel Control section. It’s here again to help find it quickly when adjusting the fueling just after the engine is started.
Afterstart 65F = This is the exact same value that is found in the Fuel Control section. It’s here again to help find it quickly when adjusting the fueling just after the engine is started.
Afterstart 170F = This is the exact same value that is found in the Fuel Control section. It’s here again to help find it quickly when adjusting the fueling just after the engine is started.
Warmup 20F = This is the exact same value that is found in the Fuel Control section. It’s here again to help find it quickly when adjusting the fueling after the engine is started and the engine is cold.
Warmup 65F = This is the exact same value that is found in the Fuel Control section. It’s here again to help find it quickly when adjusting the fueling after the engine is started and the engine is cold.

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