Electronic Engine Controls

ELECTRONIC ENGINE CONTROLS

The electronic engine controls consist of the:
- powertrain control module (PCM)
- throttle position (TP) sensor
- idle air control (IAC) valve
- engine coolant temperature (ECT) sensor
- camshaft position
- camshaft position (CMP) sensor
- crankshaft position (CKP) sensor
- mass air flow (MAF) sensor
- intake air temperature (IAT) sensor
- heated oxygen sensor (HO2S)
- knock sensor (KS)
- vehicle speed sensor (VSS)
- cylinder head temperature (CHT) sensor

The PCM needs the following inputs to calibrate the engine correctly:
- camshaft position sensor (CMP)
- engine rpm
- engine coolant temperature
- amount of engine detonation
- crankshaft position
- air temperature
- throttle position
- cylinder head temperature
- mass air flow

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

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:
- sends the PCM a signal indicating mass airflow rate of air entering the engine.

The IAT sensor:
- sends the PCM a signal indicating the temperature of the air entering the engine.
- resistance decreases as temperature increases.

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 4.6L KS is located in the lifter valley. The 5.4L has a unique linear KS located in the lifter valley:
- The KS 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 cylinder head temperature.
- If the temperature exceeds 126°C (258°F) 5.4L, 130°C (265°F) 4.6L, the PCM disables four fuel injectors at a time. The PCM will alternate which four fuel 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 (31O°F) 5.4L, 166°C (330°F) 4.6L, the PCM disables all of the fuel injectors until the engine temperature drops below 154°C (310°F) 5.4L, 153°C (308°F) 4.6L.

The VSS:
- is gear driven by the transmission.
- sends a signal to the PCM indicating vehicle speed.