Electronic Engine Controls

Electronic Engine Controls

The electronic engine controls consist of the following:

- PCM
- Cylinder Head Temperature (CHT) sensor
- Camshaft Position (CMP) sensor
- Crankshaft Position (CKP) sensor
- Power Steering Pressure (PSP) switch
- Mass Air Flow (MAF) sensor
- Heated Oxygen Sensor (HO2S)
- Catalyst Monitor Sensor (CMS)
- Knock Sensor (KS)

The PCM:

- accepts input from various engine sensors to compute the fuel flow rate and spark timing necessary to maintain a prescribed air/fuel ratio throughout the entire engine operating range.
- outputs a command to the fuel injectors to meter the appropriate quantity of fuel.

The CHT sensor:

- sends the PCM a signal indicating cylinder head temperature.
- resistance decreases as temperature increases.

The CMP sensor:

- provides camshaft position information which is used by the PCM for fuel synchronization.

The CKP sensor:

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

The PSP switch:

- is a normally closed switch that opens as pressure increases.
- is used to send a signal to the PCM to adjust idle speed. This compensates for additional load on the engine from the power steering pump.

The MAF sensor:

- uses a hot wire sensing element to measure the amount of air entering the engine.
- uses a second hot wire to measure intake air temperature.
- sends signals to the PCM. The PCM will then calculate the required fuel injector pulse width in order to provide the desired air/fuel ratio.

The HO2S:

- has the ability to create a voltage signal dependent on exhaust oxygen content.
- provides feedback information to the PCM used to calculate fuel delivery.

The CMS:

- has the ability to create a voltage signal dependent on exhaust oxygen content.
- provides feedback information to the PCM used to calculate catalyst efficiency.

The KS:

- sends a signal to the PCM indicating engine detonation, which retards the ignition timing as necessary.