Circuit Description
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The powertrain control module (PCM) uses the following readings in order to calculate the predicted mass air flow (MAF) rate:
- The throttle position (TP)
- The barometric (BARO) pressure
- The intake air temperature (IAT)
- The engine revolutions per minute (RPM)
The PCM compares the predicted MAF value to the actual MAF value, and to the speed density calculation in order to verify the proper throttle operation.