Steering: Description and Operation

IDLE-UP DEVICE

The pump produces the maximum fluid pressure when the steering wheel
is turned fully to the right or left and, at this time, there is a maximum load on the pump which causes a decrease in engine idle rpm. To solve this problem, some vehicles are equipped with an idle-up device which acts to raise the engine idle rpm whenever there is a heavy load on the pump.


EFI ENGINES

On EFI engines, when the piston of the air control valve is pushed by
fluid pressure, the air valve opens and the volume of air by- passing the throttle valve is increased to regulate engine rpm.

The idle-up device functions to raise engine idle rpm when pump fluid
pressure acts on the air control valve, installed to the pump body,to control the flow of air.