Colt L4-089 1468cc 1.5L VIN K 2-bbl (1988)
Feedback Solenoid Valve: Description and Operation
Solenoid Valve Locations
This valve is located in the carburetor float chamber cover
Solenoid Valve Duty Cycle
The ECU controls the air-fuel ratio by controlling the duty cycle of the valve. The frequency of ON-OFF cycles remain constant at 10 Hz pulses, but
the solenoid "ON" time portion of each cycle is changed to modify the duty ratio. The higher the duty ratio (the longer the ON time), the leaner the
air-fuel ratio.
Feedback Solenoid Valve (FBSV) Control System
When the FBSV is energized, the main fuel jet is closed, leaving the primary main jet passage as the only passage supplying fuel to the main circuit fuel
nozzles in the carburetor venturi. This results in a lean air-fuel mixture. When the FBSV is de-energized, the main fuel jet is opened providing a second
fuel passage to meter fuel. Since this will increase the amount of fuel already being supplied, a rich air-fuel mixture results. With the ON-OFF operation
(duty cycle) of the FBSV, the air-fuel mixture is controlled.
