Wrangler L4-150 2.5L VIN H TBI (1986)
Sol-Vac Throttle Positioner
This unit which is attached to the carburetor, consist of a solenoid and a vacuum actuator. The vacuum actuator is activated during engine start up and
during deceleration to increase engine idle speed. The holding solenoid is activated when accessories such as the air conditioner or rear window
defogger are operating to increase engine idle speed.
PCV Valve Solenoid
The PCV valve solenoid is installed in the PCV valve hose. It is energized by the MCU to turn crankcase ventilation when engine is at idle speed. The
solenoid will also momentarily energized when the ignition switch is placed in the off position to prevent air from entering below the throttle plates.
Mixture Control Unit, 4-150
The mixture control unit is an integral part of the carburetor. This solenoid is operated by the MCU and is used to provide the proper air/fuel ratio by
controlling the amount of air allowed to mix with the fuel. During open loop operation, the mixture control solenoid will allow a programmed amount of
air the air/fuel mixture. During closed loop operation, the MCU will operate the mixture control solenoid to provide more or less air for the air/fuel
mixture, depending on engine operating conditions.
Stepper Motor
The stepper motor, integral with the model BBD carburetor, controls the metering pins that vary the size of the air bleed orifices located in the
carburetor body. The motor moves the pins in and out of the orifices in steps, according to the control signal generated by the MCU. The motor has a
range of 100 steps, but the normal operating area is in the mid range. When the metering pins are stepped in the direction of the orifices, the air/fuel
mixture becomes richer: when stepped away from the orifices, the mixture becomes leaner.
