PRINCIPLES GASOLINE/DIESEL FUEL SYSTEMS - OD1620 - LESSON 1/TASK 2
FIGURE 36.
THROTTLE RETURN DASHPOT.
the throttle opens again, the dashpot spring pushes the diaphragm back into
operating position, drawing air into the chamber.
(3) Antidiesel Solenoid (figure 37 on the following page).
The
antidiesel solenoid controls the throttle opening at engine idle to prevent
dieseling.
Engine dieseling is a condition that causes the engine to
continue running after the ignition switch is turned off.
It is a
particular problem with emission controlled vehicles due to higher operating
temperatures, higher idle speeds, leaner fuel mixtures, and lower octane
gasoline. The solenoid is energized when the ignition switch is turned on,
causing the plunger to open the throttle to idle speed position.
The
plunger length is adjustable so that the idle speed can be adjusted. When
the ignition switch is turned off, the solenoid is deenergized and the
throttle closes tightly, cutting off the air-fuel mixture. This will keep
the engine from dieseling.
(4) Air-Conditioning Solenoid (figure 37).
The air-conditioning
solenoid is used on some engines to boost engine idle speed whenever the
air-conditioner compressor is running. This compensates for the load placed
on the engine, thus preventing stalling.
Its operation is similar to the
antidiesel solenoid described above.
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