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.