Electronic Engine Controls (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
• cylinder head temperature sensor
• camshaft position (CMP) sensor
• crankshaft position (CKP) sensor
• mass air flow (MAF) sensor
• intake air temperature (IAT) sensor
• heated oxygen sensor (HO2S) - front
• catalyst monitor sensor - rear
• wheel speed 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

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 cylinder head temperature sensor:

• provides a gauge signal for coolant temperature.
• is mounted on rear of LH cylinder head.
• 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.