240 L4-2.3L SOHC VIN 88 B230F (1986)
The control unit is programmed with a series of specific settings for a number of defined speeds and engine loads. These settings are stored in the ECU
as an "ignition map". This means the timing can be controlled to the accuracy of a fraction of a degree. The ignition ECU will adjust the timing
according to this "ignition map" at all times under all engine loads (except engine knock).
ANTI-KNOCK PROGRAM:
Knock causes high and dangerous combustion temperatures. The ignition system will first retard the timing in approx. 2.8° increments (to a maximum of
9.8°) to reduce knock. If knock persists, the fuel injection system will provide a richer air/fuel mixture to eliminate the knocking problem.
When the knock problem has been eliminated, the ignition ECU will advance the timing in 0.37° steps until the normal setting has been restored or
knock reoccurs.
RPM LIMITER PROGRAM:
At excess RPM the ignition is interrupted to keep the engine from overrevving.
OVERHEAT PROTECTION PROGRAM:
When the engine coolant rises above safe operation temperature, the ignition ECU will advance the timing by 13° if at idle.
STANDING CURRENT PROTECTION FUNCTION:
To avoid overheating the coil when the ignition is ON and the engine off, a separate circuit interrupts the current to the coil. The ECU uses the engine
speed and position signal to determine if the engine is running or at rest.
