A6 Quattro Sedan V8-4.2L (ART) (2000)
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Fuel Injector: Testing and Inspection
Fuel Injection Volume, Leakage and Spray Pattern Check
Fuel injection volume, fuel injector leakage and spray pattern of fuel injectors, checking
Test conditions
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Fuel pressure OK Fuel rail, removing
WARNING!
Fire hazard! Fuel system is pressurized. Before loosening hose connections or opening the test connection, place a cloth around the connection.
Then release pressure by carefully pulling off the hose or cap.
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Remove engine compartment cover and remove intake air duct between air cleaner housing and throttle housing.
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Detach vacuum hose from fuel pressure regulator.
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Disconnect connectors for knock sensors and remove cable ties where necessary.
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Detach solenoid valve for secondary air system from fuel rail.
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Disconnect harness connectors from fuel injectors and remove cable ties where necessary.
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Unscrew fuel rail from intake manifold and lift fuel rail upward off intake manifold together with fuel injectors.
Checking fuel injectors for leaks
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Place fuel injector which is to be tested into a measuring glass from VAG 1602 injection quantity tester.
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Connect VAG 1598/31 test box to wiring harness for engine control module. DO NOT connect to engine control module itself.
Bridge contacts 1 and 65 on test box using test leads from VAG 1594A connector test kit. (This creates a Ground (GND) connection to one side of
the fuel pump relay coil.)
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Switch ignition on.
NOTE:
Once the ignition has been switched on the fuel pump runs continuously, even if the engine is not running. This happens for the following reason, when
the ignition is switched on the fuel pump relay receives a positive voltage supply via the central electrics The Ground (GND) connection for the fuel
pump relay is created via the jumper wire on the test box.
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Check fuel injectors for leaks (visual check). When fuel pump is running, only 1 or 2 drops should escape per minute from each injector.
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If fuel loss is greater, switch off fuel pump (turn off ignition) and replace faulty fuel injector.
Checking fuel injection volume
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Place fuel injector which is to be tested into a measuring glass from VAG 1602 injection quantity tester.
