Passat L4-1984cc 2.0L DOHC (9A) (1990)
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K. Adjust CO Fuel Trim (FT) As Follows
K. Adjust CO Fuel Trim (FT) as follows
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With ignition OFF, disconnect hoses 1 and 2 from breather housing 3.
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Place hoses in such a way that only fresh air can be drawn in.
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Ensure that connector piece 4 (with opening) remains in hose 2.
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Disconnect differential pressure regulator harness connector -1-.
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Connect test adaptor VAG 1315A/1 between differential pressure regulator and harness connector (arrows).
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Switch Fluke 83 (US 1119) multimeter to 200mA range
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Connect multimeter to test adaptor VAG 1315A/1, using jumper leads from adaptor kit VW1594.
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Switch ignition ON. control current polarity (90 to 110 mA) must be positive If NOT, interchange test connections
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Continue on next page
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Start engine and let idle.
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Go to Engine Scan Tool and press 1 button to select "Rapid Data Transfer" mode.
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Press 0 and 1 buttons to select "Engine Electronics"
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Press 0 button to enter input.
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Press (arrow) button.
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Press 0 and 4 buttons to select "Basic Engine Adjustment".
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Press 0 button twice and press Q button.
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idle must be 800-1000 RPM
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Observe CO content
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must be 0.2 to 1.2 % Volume
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adjusting value: 2.5+/- 2.5 mA (must fluctuate)
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If NO
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Adjust control current, using CO Fuel Trim (FT) adjusting screw.
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If NO
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Check oxygen sensor (G39) and oxygen sensor control, see Repair Manual, page 25-100.
Caution!
When adjusting CO Fuel Trim (F7):
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DO NOT push down on wrench while adjusting.
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Do NOT accelerate engine while wrench is inserted in adjusting screw.
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Remove adjusting wrench after each adjustment and briefly raise engine spied before reading multimeter.
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Turn to Engine Scan Tool VAG 1551 and read Diagnostic Trouble Code (DTC).
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if a malfunction (DTC) is indicated, make appropriate corrections and then erase DTC memory.
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Install new CO tamper-proof plug, Part No. 049 133 777B,
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Disconnect all test equipment.
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Reconnect all hoses and wire harness connectors.
L. Secure Injector Fuel Lines
