Electronic Engine Controls
The electronic engine controls consist of the:
- powertrain control module (PCM)
- 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 (CMS)
- knock sensor (KS)
- cylinder head temperature (CHT) sensor
The PCM needs the following inputs to control the engine correctly:
- camshaft position
- crankshaft position
- engine rpm
- engine cylinder head temperature
- amount of engine detonation
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 and coil firing.
The CKP sensor:
- sends the PCM a signal indicating crankshaft position.
- is essential for calculating spark timing.
The MAF sensor:
- sends the PCM a signal indicating mass airflow rate of air entering the engine.
- incorporates the intake air temperature (IAT) sensor.
The HO2S and CMS:
- have the ability to create a voltage signal dependent on exhaust oxygen content.
- provide feedback information to the PCM used to calculate fuel delivery.
The KS:
- is located top forward of the block under the intake manifold.
- sends a signal to the PCM indicating engine detonation.
The CHT sensor:
- is mounted into the wall of the cylinder head and is not connected to any coolant passages.
- sends a signal to the PCM indicating the cylinder head temperature.
- If the temperature exceeds 126°C (258°F), the PCM disables four fuel injectors at a time. The PCM will alternate which four injectors are disabled every 32 engine cycles. The four cylinders that are not being fuel injected act as air pumps to aid in cooling the engine.
- If the temperature exceeds 154°C (310°F), the PCM disables all of the fuel injectors until the engine temperature drops below 154°C (310°F).