Computers and Control Systems: Description and Operation
The electronic engine controls consist of the following:- Powertrain Control Module (PCM)
- Throttle Position (TP) sensor
- Idle Air Control (IAC) valve
- Engine Coolant Temperature (ECT) sensor
- Camshaft Position (CMP) sensor
- Crankshaft Position (CKP) sensor
- Mass Airflow (MAF) sensor
- Intake Air Temperature (IAT) sensor
- Heated Oxygen Sensor (HO2S) - front
- catalyst monitor sensor-rear
- wheel speed sensor
- engine water temperature sensor
The powertrain control module needs the following inputs to calibrate the engine correctly:
- crankshaft position
- engine rpm
- engine load (manifold pressure)
- atmospheric (barometric) pressure
- engine coolant temperature
- amount of engine detonation
The throttle position sensor:
- sends the powertrain control module a signal indicating the throttle plate angle.
- is the main input to the powertrain control module from the driver.
The idle air control valve:
- controls bypass air around the throttle plate at low speeds.
- is controlled by the powertrain control module.
The engine coolant temperature sensor:
- provides a gauge signal for coolant temperature.
- is mounted on top of the intake manifold.
- sends the powertrain control module a signal indicating engine temperature.
- resistance decreases as coolant temperature increases.
The camshaft position sensor:
- sends the powertrain control module a signal indicating camshaft position, used for fuel synchronization.
The crankshaft position sensor:
- sends the powertrain control module a signal indicating crankshaft position.
- is essential for calculating spark timing.
The mass air flow sensor:
- sends the powertrain control module a signal indicating mass air flow rate of air entering the engine.
The intake air temperature sensor:
- sends the powertrain control module a signal indicating the temperature of the air entering the engine.
The heated oxygen sensor:
- has the ability to create a voltage signal depending on exhaust oxygen content.
- provides feedback information to the powertrain control module used to calculate fuel delivery.
The rear catalyst monitor sensor:
- monitors oxygen content after the oxygen flows through the catalytic converter.
- provides a voltage to the powertrain control module used to calculate catalytic converter integrity.
The wheel speed sensor:
- sends a signal to the powertrain control module indicating wheel speed.