DESCRIPTION
The Pulse Air Injection Reactor (PAIR) system is used on some 2.0L 4-cylinder engines.
This system is a non-pump type air injection system. This system uses engine exhaust pulses to draw fresh air into the exhaust system.
This helps to further oxidize hydrocarbon (HC) and carbon monoxide (CO) emissions. A single pulse air valve is used.
OPERATION
The firing of the engine creates a pulsating flow of exhaust gases. When positive exhaust pressure is felt, the check valve will be forced closed and no exhaust gas will flow past the valve into the fresh air supply line.
With negative exhaust pressure (vacuum), the check valve will open and fresh air will be drawn in and mixed with the exhaust gases. During high engine RPM, such as under heavy acceleration, the check valve will remain closed.
Air supply to the pulse air system is controlled by an electric and vacuum shut-off valve operated by the Computer Command Control (CCC) system.
When the engine starts and is operating in the open loop mode, the valve is energized and the fresh air line is opened.
When the CCC switches into closed loop mode, valve is de-energized and fresh air line is closed.
Pulse Air Injection Reactor System (Some 2.0L 4-Cylinder Engines). Scheme 24
PULSE AIR SOLENOID CHECK
- Remove air cleaner to gain access to pulse air solenoid hose. Make sure that hose is properly connected. Turn ignition off for 1 minute.
- Start engine and feel for vacuum pulsations at end of pulse air hose. Pulsations should occur for at least 20 seconds after engine starts.
- If pulsations are felt as described, turn ignition "OFF" and open distributor "set timing" connector. Start engine. There should be pulse air momentarily. Pulse air should stop. If pulse air is okay, reconnect "set timing" connector and review symptoms.
- If pulsations were not felt in step 2), turn ignition "ON" with engine stopped and "set timing" connector connected. Disconnect pulse air solenoid harness and connect a test light between connector terminals. If light is "ON" repair short to ground in wiring harness.
- If light in step 4) is "OFF", ground diagnostic terminal and again note test light between connector terminals. If light is still "OFF," connect light between each connector terminal to ground and check light.
- If light is "OFF" on both terminals, repair open circuit in wiring harness. If light is "ON" on 1 terminal, check for open circuit from solenoid to ECM. If wiring harness is okay and ECM connectors are okay, check for faulty ECM. If light is "ON" on both terminals, check for short circuit to battery voltage and recheck circuit. Short to battery voltage could damage ECM.
- If light between connectors is "ON" after grounding diagnostic terminal in step 5), reconnect solenoid. With engine idling and diagnostic terminal not grounded, disconnect vacuum hose to control solenoid and test for more than 10 in. Hg. If vacuum is not present, repair vacuum source.
- If vacuum in step 7) is okay, turn ignition "OFF" and be sure diagnostic terminal is not grounded. Reconnect vacuum hose to solenoid and disconnect vacuum hose at pulse air valve. Connect vacuum gauge to hose. Start and idle engine, note gauge. Gauge should read 6 in. Hg for at least 6 seconds.
- If vacuum reading is not okay, check for plugged hose or defective solenoid or solenoid connector. If vacuum reading is okay, apply 10 in. Hg to pulse air valve with engine idling. Air pulsation should be heard or felt at the air cleaner pulse air intake hose.
- If air pulsation is felt, system is okay. If no pulsation is felt, problem is faulty pulse air intake hose or control valve assembly.