AIR INJECTION SYSTEM
injection system (fig. 4-51)
forces fresh air into the exhaust ports of the engine to reduce HC and CO emissions. The
exhaust gases leaving an engine can contain unburned and partially burned fuel. Oxygen
from the air injection system causes this fuel to continue to burn. The major parts of the
system are the air pump, the diverter valve, the air distribution manifold, and the air
AIR PUMP is belt-driven and forces air at low pressure into the system. A hose is
connected to the output of the diverter valve.
DIVERTER VALVE keeps air from entering the exhaust system during deceleration. This
prevents backfiring in the exhaust system. Also, the diverter valve limits maximum system
air pressure when needed, releasing excessive pressure through a silencer or a muffler.
DISTRIBUTION MANIFOLD directs a stream of fresh air toward each engine exhaust valve.
on the air distribution manifold screw into a threaded hole in the exhaust manifold or
CHECK VALVE is usually located in the line between the diverter valve and the air
distribution manifold. It keeps exhaust gases from entering the air injection system.
operation of the air injection system is as follows:
the engine is running, the spinning vanes of the air pump force air into the diverter
valve. If not decelerating, the air is forced through the diverter valve, the check valve,
the air injection manifold, and into the engine. The fresh air blows on the exhaust
periods of deceleration, the diverter valve blocks air flow into the engine exhaust
manifold. This prevents a possible backfire that could damage the exhaust system of the
vehicle. When needed, the diverter valve will release excess pressure in the system.