The air bypass valve supplies air to the exhaust system with medium and high applied vacuum signals when the engine is at normal operating temperature. With low or no vacuum applied, the pumped air is dumped through the silencer ports of the valve or through the dump port.
- Turn the ignition key OFF .
- Remove the control vacuum line from the bypass valve.
- Start the engine and bring to normal operating temperature.
- Check for vacuum at the vacuum line. If there is no vacuum, check the solenoid vacuum valve assembly. If vacuum is present, inspect the air bypass valve.
- Turn the engine OFF and disconnect the air hose at the bypass valve outlet.
- Inspect the outlet for damage from the hot exhaust gas.
- If the valve is damaged, replace it. If the valve is not damaged, check the bypass valve diaphragm.
- Connect a vacuum pump to the bypass valve and apply 10 in. Hg of vacuum.
- If the valve holds vacuum, leave the vacuum applied and proceed to Step 10. If the valve does not hold vacuum, it must be replaced.
- Start the engine and increase the engine speed to 1500 rpm.
- Check for air flow at the valve outlet, either audibly or by feel. If there is air flow, proceed to Step 12. If there is no air flow, replace the air bypass valve.
- Release the vacuum applied by the vacuum pump and check that the air flow switches from the valve outlet to the dump port or silencer ports, either audibly or by feel.
- If the air flow does not switch, replace the air bypass valve. If the air flow switches, the air bypass valve is okay, check the air supply control valve.
REMOVAL & INSTALLATION
- Disconnect the negative battery cable.
- Disconnect the air inlet and outlet hoses and the vacuum hose from the bypass valve.
- Remove the bypass valve from the vehicle.
- Installation is the reverse of the removal procedure.