The computer uses data from these OBDII sensors
Intake air temperature (IAT) sensor
to help calculate air/fuel mixtures. The IAT is usually located in the air duct from the air filter box to the throttle body. Or, it can be located after the throttle body somewhere in the upper plenum of the intake manifold.
In use, the computer looks at data from the engine coolant temperature (ECT) so it knows if the engine is cold, then it looks at the IAT to see the temp of the outside air. Finally, it looks at either the manifold
absolute pressure (MAP) or the mass airflow
(MAF) to determine the density of the air. Once it knows all those variables, it can determine a starting air/fuel mixture.
© 2012 Rick Muscoplat
Posted on by Rick Muscoplat