Civic L4-1493cc 1.5L SOHC (8 valve) (1992)
Engine Control Module: Description and Operation
Modes of Operation
System Description
The ECU contains memories for the basic discharge durations of the fuel injectors (determining the air/fuel mixture) at various engine speeds and
manifold pressures. The basic discharge duration of the fuel injector is modified by signals from various sensors to obtain the final discharge duration.
The oxygen sensor is a main input component for the air/fuel mixture control.
CONTROL FUNCTIONS:
1.
Electronic Air Control Valve (EACV):
When the engine is cold, the A/C compressor is ON, the transmission is in gear (automatic transmission), and/or the alternator is charging, the
ECU controls current to the electronic air control valve (EACV) to maintain correct idle speed.
2.
Ignition Timing Control:
The ECU contains memories for basic ignition timing at various engine speeds, manifold pressures and the coolant temperature.
3.
Starting Control:
When the engine is started, the ECU provides a rich mixture.
4.
Fuel Pump Control:
When the ignition is initially switched ON, the ECU supplies ground to the main relay which supplies current to the fuel pump for 2 seconds to
pressurize the system.
When the engine is running, the ECU supplies ground to the main relay which supplies current to the fuel pump.
When the engine is not running and the ignition is turned ON, the ECU cuts the ground to the main relay which cuts the current to the fuel pump.
5.
Fuel Cut-Off Control:
During deceleration with the throttle valve closed, current to the injectors is cut-off to improve fuel economy at engine speeds over the following
rpm's.
8 valve engine (D15B8):
M/T: 920 rpm
A/T: 900 rpm
16 valve engine (D15B7):
870 rpm
16 valve VTEC-E engine (D15Z1):
850 rpm
Fuel cut-off also takes place when engine speed exceeds the following RPM'S, regardless of throttle valve position, to protect the engine from
over-revving.
8 valve engine (D15B8):