The function of the fuel metering system is deliver the correct amount of fuel to the engine under all operating conditions. Fuel is delivered to each cylinder by the fuel injectors. The fuel injectors are controlled sequentially by the powertrain control module (PCM). The PCM bases the control of the fuel injectors on several important engine parameters. These engine parameters include the following:
| • | The mass air flow (MAF) sensor |
| • | The intake air temperature (IAT) sensor |
| • | The engine coolant temperature (ECT) sensor |
| • | The throttle position (TP) sensor |
| • | The heated oxygen sensor (HO2S) |
Determining air density is critical to proper air/fuel management. Air density is primarily derived from the MAF sensor input. The MAF sensor measures the air volume and determines the air density. Larger volumes of air and denser air masses require additional fuel. The information from the MAF sensor is used by the PCM in order to modify the fuel injector pulse width.
The fuel metering system consists of the air/fuel delivery system and the electronic control system. For information on the electronic control system refer to
Powertrain Control Module Description
and
Information Sensors/Switches Description
.
