7.1 Basic / Load Sections 7 ADDITIONAL ITEMS: BEYOND BASIC FUEL AND IGNITION CONTROL
7.1.11.7 Tuning For Idle Air Control The Idle TPS Threshold % setting defines the minimum TPS value re-
quired to allow the transition to Alpha-N tuning. This feature allows the fast idle MAP to exceed the %Baro switch-
point without entering Alpha-N mode. On engines with aggressive cams with higher overlap, it is possible for the
fast idle MAP to exceed the %Baro switchpoint. When this happens, you do not want to enter Alpha-N mode tuning
since the throttle is still reading fully closed. The Idle TPS Threshold % prevents you entering Alpha-N mode and
you can use the warm up enrichment curve to compensate for any tuning errors caused by being stuck at the
maximum Speed-Density bin while the MAP is greater than the %Baro switchpoint.
7.1.12 MAF options
Mass air flow (MAF) sensors provide a measurement of actual airflow through the intake system of an engine. In
its most basic form, the fuel required by the engine (in mass per second) is directly related to the air flowing into the
engine (in mass per second), so the MAF sensor should give a good basis for the fuel equation. (By comparison,
Speed Density uses RPM, MAP, MAT and VE to estimate the mass air flow.) In practice, like any other sensor
input, the MAF has its own quirks and can suffer from reversion effects (particularly on "cammy" engines) where
the air flow gets measured twice.
The MS3Pro implementation of MAF consists of the following main elements:
• Engine and injector parameters
• MAF calibration curve
• Optional trim table
Before setting up the MAF options, be sure you have the right parameters set under Engine and Sequential
Settings. The critical settings to enter here are:
• Engine Stroke
• No. cylinders/rotors
• Number of Injectors
• Engine size
• Injector size each.
Having entered those details, click on the Required Fuel button to calculate the global fuel constant. You may need
to re-enter the numbers if the calculator doesn’t pick them up automatically. Make sure you set the correct units.
AMP EFI MS3Pro manual version 1.202, firmware 1.5.0, 4/21/2017 Page 145
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