AEM 30-71XX Infinity Stand-Alone Programmable Engine Mangement System Full Manual - Manual (Page 291)

EFI Components 285
© 2014 AEM Performance Electronics
TPS (Throttle Position Sensor)
The TPS determines the position of the throttle blade in the throttle body. This input is used to
determine rate of throttle angle change (both positive and negative), idle position, and discrete
throttle opening for TPS-based calibrations. The TPS typically is a potentiometer bolted to the
end of the throttle shaft. Rotating the throttle varies the resistance, and consequently, the voltage
returned to the ECU is a function of that resistance. The rate of change is measured to
determine whether a vehicle is accelerating or decelerating. Based on this rate of change, the
proper amount of fuel is either added or subtracted from the base calibration to achieve the
proper amount of fuel for the operating condition.
The TPS is also used to determine if the vehicle is idling. When the throttle is at rest, the vehicle
is considered to be either idling or under heavy deceleration, and the fuel and ignition
calibrations are adjusted for optimum idle characteristics. The TPS can be used as a calibration
input if the AEM Infinity is set up to be a throttle position vs. RPM based mapping scheme. This
type of mapping allows the tuner to set up the fuel map based on the throttle angle from 0 to
100% on the Y-axis of the map, with the X-axis being RPMs. This type of mapping is usually best
for naturally aspirated racing engines with individual runner inlet manifolds and no plenum
chamber or very aggressive cams.
While on the subject of throttle opening we must caution you to make sure that full throttle is
achieved by having someone verify that the throttle blade is opening fully and up against the stop
on the throttle body while you depress the throttle. Also, make sure that nothing interferes with
the full range of the throttle opening, such as a floor mat.