The Harely Davidson efi tuner twin cam MSD FI Enhancer is preprogrammed with four base fuel curves. The curves are selected using the switch labeled BASE. These curves adjust fuel delivery based on throttle position and rpm, providing the right amount of fuel under all conditions. The four fuel curves correspond to varying levels of performance modifications. These levels of modification are broken down into the following groups:
Curve 1 - Stock or base modifications. This includes slip on exhausts, intakes, air boxes, and air filters.
Curve 2 - Bolt on modifications such as a full exhaust system.
Curve 3 - Engine modifications, including cams, big bore kits, etc.
Curve 4 - The fourth curve has all of the fuel adjustment values zeroed out. This curve is selected by moving the rotary switch to any position other than Base 1, Base 2 or Base 3. This curve is useful for those wanting to just modify the fuel delivery with the potentiometer adjustment, without having any other adjustments.
In addition to the four curves, there are three potentiometers that allow you to fine tune the curve you select. These potentiometers allow you to adjust the fuel curve from +20% to -20% in three different rpm ranges.
The rpm ranges are: Low - Idle - 2,000 rpm Mid - 2,000 - 4,000 rpm High - 4,000 - 6,000 rpm
To add fuel, turn the potentiometer clockwise.
To subtract fuel, turn the potentiometer counterclockwise.
With the potentiometer pointed straight up at the thick indicator mark (towards the MSD logo), that is 0% adjustment.
Fully CCW is -20%, and fully CW is +20%.
Adjusting the potentiometer between these points will result in adding or subtracting an amount of fuel proportional to how far the knob was moved from zero.
The FI Enhancer has an LED that will illuminate when there is power to the unit.
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