Dual Air Pumps

Air Injection System:

SYSTEM OPERATION

The air injection system is composed of two belt-driven air pumps, two air control valves (diverter valves), rubber hoses, check valves to protect the hoses, and injection tubes. This system adds a controlled amount of air to the exhaust gases aiding the reduction of hydrocarbons and carbon monoxide in the exhaust stream.
Air passes through the plastic centrifugal filter fans at the front of the air pumps, and foreign materials are filtered out of the air by centrifugal force. Air is only injected to the exhaust ports next to the exhaust valves. There is no air switch relief valve or air switching solenoid in this system.


CHECK VALVE

The check valves are located in the injection tube assemblies. The purpose of the check valve is to protect the air injection system in the event that the air pump belt fails, exhaust system pressure raises to an abnormally high level, or an air hose ruptures. This valve has a one way diaphragm which prevents hot exhaust gases from getting to the rubber hoses or the air pump.

Power Heat Control Valve:

POWER HEAT CONTROL VALVE

The power heat valve is located between the right exhaust manifold and exhaust pipe. It is a vacuum operated device which directs most of the exhaust flow to the left-hand exhaust manifold. This redirecting of exhaust helps to improve cold engine driveability, and also warms the oxygen sensor.

The power heat valve is controlled by an electronic solenoid. This solenoid controls the manifold vacuum signal which is used to activate the power heat valve. At coolant temperatures below a predetermined level, manifold vacuum is applied to the power heat valve and all exhaust flow is directed to the left-hand exhaust manifold. Once the coolant temperature rises above the predetermined level, then the solenoid closes off the vacuum signal and the power heat valve opens allowing exhaust to flow through both manifolds.

Diverter Valve:

DIVERTER VALVE

The diverter valve's purpose is to prevent backfire during deceleration. The diverter valve senses changes in manifold vacuum. When decelerating, vacuum increases rapidly. This increase causes the valve to open thus allowing air from the air pump to vent through the silencer and out to the atmosphere. When accelerating, vacuum drops rapidly. This decrease in vacuum causes the valve to shut allowing air to flow either upstream or downstream.
A pressure relief valve is also incorporated into the diverter valve. It's purpose is to allow excessive air pump output to be vented to the atmosphere under high system pressure conditions (approximately 9 psi), specifically high engine speeds.