User guide

54 www.AutoEnginuity.com
IAT or Intake Air Temperature
Ambient temperature taken from as far away from the engine as
possible to get an accurate reading. It is used to help determine the
fuel mixture and manifold pressure.
Intake Manifold
Is the final conduit for getting the air, and sometimes the fuel, to the
intake valve. The design of the intake manifold has a great deal to
do with the creation and control of horsepower and torque.
Knock Sensor
Measures how each cylinder is firing. If one cylinder is firing too
soon or too late, or even if it fires twice, a knock or ping is pro-
duced. The sensor sends a signal to the computer, which will either
adjust the timing on the ignition or the camshaft. “Knocking” is not
common, but the special conditions under which it will most com-
monly occur are with high manifold pressure, bad fuel, bad spark
advance, or improper engine cooling.
KOEO
Key On Engine Off, a specific state of the vehicle where the
ignition key is turned to the “ON” position but the engine is not
started.
KOER
Key On Engine Running, a state of the vehicle where the engine has
been started and allowed to run. OBD-II system download and a
visual check of the MIL occurs during the KOER state.
Low Input
Circuit voltage, frequency, or other signal measured at the control
module input terminal or pin that is at or near zero. It is measured
with the external circuit, component, or system connected.
LTFT or Long Term Fuel Trim
The engine computer is always learning how your vehicle is being
driven. If you drive slowly, it stores that information; and, if you
drive fast, it also stores that. In addition, the engine computer will
compensate or adapt for a part of the engine that has become defec-