Electronic Engine Controls
WARNING: This page is about a different car, the 2005 Mazda Tribute. However, it is still accessible from the selected car via links, so may be relevant.
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)
- 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)
- intake manifold tuning valve (IMTV)
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):
- 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.