Edelbrock 3670 User Manual - page 138
138
4.3.9
IAT Fuel Trim Table
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IAT Fuel Trim Table
IAT Fuel Trim Table
(Not Available in Speed density Mode)
In Speed/Throttle (Alpha-N) mode or Speed/Pressure (MAP-N) mode, there is the ability
to adjust a global trim for fuel based upon IAT. This can be useful if fueling
characteristics change greatly with engine coolant temperature. While not often needed,
the IAT Fuel Trim table can be helpful in providing a global fuel offset for a variety of
intake charge temperatures. This table is not necessary in Speed/Density mode, as
charge temperature is automatically compensated for.
Tips for tuning
:
The table is a multiplier to the base fuel map. It is based on intake air temperature in
degrees C. or degrees F. (Whichever you have chosen as your desired units of pressure in
the application settings.) A value of "1.00" means that no change is being applied to the
base map. This means that a value of 1.00 equals the calibrated base fueling and no
change is being applied to the end pulse width of the injector. A value of 1.10 equals
10% more fuel is being delivered than is mapped. 1.15 means that 15% more fuel is
being delivered, and so on. Keep the values small. If a large value is required, it probably
means that your base fuel map calibration is not optimized, and you should adjust the
base fuel map further with a representative coolant temperature. Set the value to 1.00 at
normal operating temperature. Calibrate your base fuel map. Retest at various air
temperatures and adjust the corresponding trim cell to have the system deliver the
fueling required to match your desired mapped AFR at those points.