1994 Passat Wagon V6 EGR Valve Location: Page 3655
EGR Valve: Testing and Inspection
REQUIREMENTS
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Engine coolant temperature at least 176°F (80°C).
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All electrical consumers (including A/C) switched OFF.
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Radiator fan must not run while performing tests
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Vacuum connections tight and without leaks.
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Vacuum hoses not pinched or plugged.
Testing Vacuum Diaphragm
EGR Valve Testing
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Disconnect vacuum hose from EGR valve.
NOTE DO NOT run engine during this test.
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Using hand vacuum pump, apply vacuum to EGR valve.
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Vacuum should hold without dropping
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If vacuum drops, or will not build up:
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Check hose connections for leaks
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Check vacuum pump operation
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If pump and lines are OK, replace EGR valve
Testing Exhaust Gas Flow
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With the engine running, apply 400 mm (16 in.) Hg of vacuum to the valve and observe the results:
a. The engine speed must drop while applying vacuum.
b. The engine speed should return to normal after releasing vacuum from the valve.
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If the engine speed does not change, the EGR the passage could be blocked.
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Check the EGR valve, lines, and ports in the intake and exhaust manifolds for blockage and clean out or repair as necessary.