Pulse Air System Honda Accord III

DESCRIPTION

All carbureted models are equipped with a Pulse Air System (also called Secondary Air Supply System). This system uses vacuum pulses in the exhaust manifold to draw air from the air cleaner to the exhaust manifold.

OPERATION

When vehicle manifold vacuum is above set vacuum of control switch, control switch solenoid valve and control switch are open. The control unit energizes the air suction control solenoid valve, applying manifold vacuum to air suction cut-off diaphragm valve. This will in turn open secondary air passage.

When vacuum, induced by pulsation in exhaust manifold, makes air suction reed valve open, fresh air enters exhaust manifold. The control switch bellows adjust their operation in response to atmospheric pressure. Air chambers act as silencers to reduce exhaust noise.

Scheme 18

CONTROL UNIT CONNECTOR

1. Turn ignition on and check for voltage at control unit connector (Blue wire). Voltage should be present. If there is no voltage, check Blue wire between ignition coil and control unit.
2. Turn ignition on and check for voltage at Black/Yellow wire. If there is no voltage, check wiring. Check Black wire for continuity between electronic control unit and ground. Continuity should be present.

VACUUM SWITCH C

1. Disconnect vacuum hose No. 14 to control box from vacuum hose manifold and connect vacuum pump. Remove control box from firewall. Remove control box cover.
2. Check for continuity between vacuum switch C terminals. Continuity should be present when more than 4 in. Hg is applied, and no continuity when vacuum is released.

Scheme 19

1. Disconnect and plug air suction hose from air control valve B. Remove air cleaner cover and filter. Start engine and run at idle speed. Check for bubbling noise from air suction port. (Scheme 20)
2. If bubbling noise is heard, proceed to step 6). If bubbling noise is not heard, disconnect hose No. 5 from air suction valve and check for vacuum. If vacuum is present, replace air suction valve and retest. If vacuum is not present, reconnect hose No. 5.
3. Disconnect hose No. 15 from control box at vacuum hose manifold and check for vacuum at vacuum hose manifold. If there is no vacuum, check vacuum hose No. 24. If okay, replace air bleed valve A and retest.
4. If vacuum is present, check for voltage at air suction control solenoid valve Blue/Yellow wire. If voltage is not present, check speed sensor, thermosensor and vacuum switch B (man. trans.). Check vacuum switch C. Remove control box cover.
5. Check for continuity at vacuum switch C terminals with engine at idle speed. (Scheme 20) If continuity is present, replace air suction control solenoid valve and retest. If there is no continuity, ensure No. 20 vacuum hose is clear. Replace vacuum switch C and retest.
6. Heat air bleed valve A to 140°F (60°C). Ensure bubbling noise stops. If bubbling noise continues, replace air bleed valve. Allow air bleed valve to cool before proceeding.
7. Disconnect hose No. 20 from control box at vacuum hose manifold. If bubbling noise stops, system is okay. If bubbling noise continues, disconnect hose No. 5 from air suction cut-off diaphragm and check for vacuum. If there is no vacuum, replace air suction cut-off diaphragm and retest.
8. If vacuum is present, disconnect vacuum hose from vacuum switch C. Check for continuity between terminals of vacuum switch C. If continuity is present, replace vacuum switch C and retest. Disconnect vacuum hose No. 7 at vacuum hose manifold. Attach vacuum pump to hose.
9. With engine at 2000 RPM, apply at least 2.4 in. Hg to hose. Bubbling noise should discontinue. If bubbling noise stops, system is functional and test is complete. If bubbling noise continues, check speed sensor, thermosensor and vacuum switch B (man. trans.). Check vacuum switch C.

Scheme 20

Scheme 21