Powertrain Management: Description and Operation

ELECTRONIC ENGINE CONTROLS

The electronic engine controls consist of the following:

- Powertrain control module (PCM)
- Cylinder head temperature (CHT) sensor (2.3L)
- Engine coolant temperature (ECT) sensor (3.0L [4V])
- Throttle position (TP) sensor
- Idle air control (IAC) valve
- Camshaft position (CMP) sensor
- Crankshaft position (CKP) sensor
- Mass air flow (MAF) sensor
- Heated oxygen sensor (HO2S)
- Catalyst monitor sensor
- Knock sensor (KS) (2.3L)The PCM carries out the following functions:

- accepts input from various engine sensors to compute the fuel flow rate necessary to maintain a prescribed air/fuel ratio throughout the entire engine operational range.
- outputs a command to the fuel injectors to meter the appropriate quantity of fuel.The CHT sensor (2.3L):

- sends the PCM a signal indicating cylinder head temperature.
- resistance decreases as coolant temperature increases.The ECT sensor (3.0L [4V]):

- sends the PCM a signal indicating engine temperature.
- resistance decreases as coolant temperature increases.The TP sensor:

- sends the PCM a signal indicating the throttle plate angle.
- is the main input to the PCM from the driver.
The IAC valve:

- controls bypass air around the throttle plate at low speeds.
- is controlled by the PCM.The CMP sensor:

- sends the PCM a signal indicating camshaft position used for fuel synchronization.The CKP sensor:

- sends the PCM a signal indicating crankshaft position.
- is essential for calculating spark timing.The MAF sensor:

- uses a hot wire sensing element to measure the amount of air entering the engine. Air passing over the hot wire causes it to cool.The HO2S:

- creates a voltage signal dependent on exhaust oxygen content.
- provides feedback information to the PCM used to calculate fuel delivery.The catalyst monitor sensor:

- monitors oxygen content after it flows through the catalytic converter.
- provides a voltage to the PCM used to calculate catalytic converter integrity.The KS (2.3L):

- is used to detect engine detonation.
- sends a voltage signal to the PCM.
- is able to provide a signal which retards the ignition timing, as necessary.