Vanagon F4-1915cc 1.9L (Water Cooled) (1983)
Distributor Advance Unit: Testing and Inspection
Vacuum Advance, Checking
Vacuum advance, checking
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Connect VAG 1368 tester or equivalent according to manufacturer's instructions.
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Connect vacuum tester between throttle valve housing and vacuum advance unit connection.
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Set vacuum tester to allow vacuum to pass through.
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Pull off hose from vacuum retard unit.
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Disconnect plugs from idle stabilizer control unit and connect together.
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Start engine and adjust idle speed to 900 RPM.
Checking with TDC sensor:
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note advance angle on tester (basic advance angle).
Checking with timing light:
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Shine timing light on ignition timing scale and note indicated angle (basic angle).
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Increase engine speed until reading on vacuum tester is higher than 360 mbar (270 mm Hg)
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Switch vacuum tester so that it holds vacuum on side connected to vacuum unit.
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Leave engine running at idle: 900 RPM
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Reduce vacuum on vacuum tester to 360 mbar (270 mm Hg) or 190-230 mbar (140-170 mm Hg).
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Note advance angles.
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Determine vacuum advance by subtracting basic advance angle from measured advance angle
Example
Last advance angle measured (-) minus basic advance angle (=) vacuum advance
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Compare vacuum advance angles with specified values on specification chart.
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Readjust idle speed.