Corona L4-2366cc 22R (1982)
Deceleration Valve: Description and Operation
This system is used to prevent overheating and/or afterburning in the exhaust system when the vehicle is decelerating by momentarily cutting off
the fuel supply in the system.
System Operation
1977
While the vehicle is operating with engine speed below 2100 RPM and/or carburetor vacuum is below 13 inches Hg, the computer is turned on by
the signal from the ignition switch and/or vacuum switch. Under this condition, the battery current energizes the fuel cut solenoid and opens the
slow circuit of the carburetor.
When decelerating, if engine speed is above 2100 RPM and carburetor vacuum is above 13 inches Hg, the computer deactivates the fuel cut
solenoid and closes the slow circuit in the carburetor. Under this condition, the fuel from the float chamber does not flow into the slow circuit.
This action is delayed for 1.5 seconds by the delay circuit of the computer.
1978-82 Except 1980 1A-C & 1981-82 3A-C Engine
When engine speed is below 2000 RPM for 1978-79 2T-C an 3K-C, and 1980-82 3T-C engines, below 2400 RPM for 1978-80 20R engines, or
below 2200 RPM for 1981-82 22R engines, the vacuum switch is on during low vacuum and off during high vacuum in vacuum switch. Under
these conditions, the computer and fuel cut solenoid valve, or first fuel cut solenoid valve, are open, opening slow circuit in carburetor.
When engine speed is above 2390 RPM for 1978-79 2T-Can 3K-C and 1980-82 3T-C engine, above 2790 RPM for 1978-80 20R engine, or above
2590 RPM for 1981-82 22R engine, the vacuum switch is on when low vacuum is present in switch and off when high vacuum is present. Under
these conditions, the computer fuel cut solenoid or first fuel cut solenoid and slow circuit in carburetor are on or open during low vacuum or off or
closed during high vacuum.
1980 1A-C & 1981-82 3A-C Engine
When vacuum in vacuum switch is below 6.3 inches Hg. the vacuum switch is on, the second fuel cut solenoid valve is on, and the second slow
circuit in the carburetor is open. When vacuum in vacuum switch is above 8.85 inches Hg. the vacuum switch is off, the second fuel cut solenoid
valve is off, and the second slow circuit in carburetor is closed.
