7.4 Startup / Idle 7 ADDITIONAL ITEMS: BEYOND BASIC FUEL AND IGNITION CONTROL
• ASE count units - You may set the afterstart enrichment to be based on either time or engine cycles.
7.4.2 Cranking Taper Curve
This curve provides a multiplier for the pulse width during cranking, with 100% being to use the cranking pulse
width curve unchanged. The curve will repeat itself after reaching the end point. On some engines, an initial spike
of fuel followed by pulling fuel can lead to better startup performance.
7.4.3 Priming Pulse 2 through Warmup Enrichment 2
These are used in dual fuel mode or a blend curve (see Table Choices) if running on an alternate fuel, as different
fuels have different behavior when cold. An extreme case is CNG (compressed natural gas), which has almost no
tendency to stick to the intake walls even on the coldest engine. This means an engine running CNG will require
very little warmup or afterstart enrichment. E85 often requires different cranking pulses from gasoline as well, both
because it has a lower air/fuel ratio and because it is more likely to stick to a cold intake manifold.
7.4.4 Idle control
The MS3Pro firmware has several methods for controlling idle speed, besides the “not run any sort of ECU
control, and just use a set screw to hold the throttle open” method. They were introduced in section 5.4, but we
will cover them again in more detail.
The current firmware allows you to specify the valve type separately from open vs closed loop operation.
• Idle valve type
– None: The MS3Pro does not control idle speed.
– On/Off Valve: The valve is a two wire solenoid that can only turn on or off with no in between positions.
– PWM valve: A solenoid type valve where the amount of opening is controlled by the output duty cycle.
AMP EFI MS3Pro manual version 1.202, firmware 1.5.0, 4/21/2017 Page 181
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