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 to calculate the predicted mass air flow (MAF) rate:
- The throttle position (TP)
- The barometric pressure (BARO)
- The intake air temperature (IAT)
- The engine 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.