Clean Air System
Gradually raise the vacuum (lower the pressure) applied
to the vacuum switch valve, and check the valve opera-
tion. When the vacuum is low, the vacuum switch valve
should permit air to flow. When the vacuum raises to
valve closing pressure, it should stop air flow.
Low Vacuum [D]
Secondary air flows [E].
If the vacuum switch valve does not operate as described,
replace it with a new one.
To check air flow through the vacuum switch valve, just
blow through the air cleaner hose.
Vacuum Switch Valve Closing Pressure (Open → Close)
Standard: 49.3 ∼ 57.3 kPa (370 ∼ 430 mmHg)
High Vacuum [A]
Secondary air cannot flow [B].
Clean Air System Hose Inspection
Be certain that all the hoses are routed without being flat-
tened or kinked, and are connected correctly to the right
air cleaner base, vacuum switch valve, throttle body, and
air suction valve covers.
If they are not, correct them. Replace them if they are
ENGINE TOP END 4-11