Fuel Injectors, Checking
Fuel injectors, checking
Special tools, testers, measuring instruments and auxiliary items required
WARNING!
Fire Hazard! Do NOT have anything in area that can ignite fuel!
- VAG 1551/1552 Scan Tool with VAG 1551/3B adaptor cable
- VAG 1598/22 Test Box
- Fluke 83 Multimeter
- VAG 15276 Voltage tester
- VW 1594 Adaptor kit
- VAG 1348/3A Remote control with VAG 1348/3-2 adaptor cable
- Wiring diagram
Checking conditions
- Engine speed sensor OK, checking, Refer to "Engine Speed Sensor" under "Computers and Control Systems", Testing and Inspection
- Fuel pump relay OK
- Fuse 34 OK.
WARNING!
Fuel system is under pressure! Before opening the system place a cloth around the connection. Then release pressure by carefully loosening the connection.
Activation,checking
- First check activation of Fuel injectors via Output Diagnostic Test Mode (DTM), [1][2][3]Output Diagnostic Test Mode (DTM) (Function 03)
If one or more injectors do not click, continue checking activation as follows
- Disconnect 5-pin harness connector -1- from Ignition coil Power Output stage -2-.
- Disconnect all Fuel injector harness connectors
- Connect VAG 1527 B Voltage tester to cyl. 1 connector terminals using jumper wires from VW 1594 adaptor kit.
- Operate starter and check Voltage supply for cyl. 1 Fuel injector
- LED must flicker
- Repeat check at remaining injector connectors
- Switch OFF ignition.
If LED does not flicker for any cylinder checked:
- Connect VAG 1527B Voltage tester between cyl. 1 harness connector terminal 1 and Ground.
- Operate starter.
- LED tester must light up
If LED does not light up:
- Switch OFF ignition
- Check wiring for open circuit between 2-pin harness connector terminal 1 and fuel pump relay J17 using Wiring diagram.
- Wire resistance: max. 1.5 Ohms
If LED flickers on one or several cylinders:
- Connect VAG 1598/22 Test Box to Engine Control Module harness connector.
- Check wiring for open circuit between Test Box and connector using Wiring diagram.
Injector 1: Terminal 2 + socket 73
Injector 2: Terminal 2 + socket 80
Injector 3: Terminal 2 + socket 58
Injector 4: Terminal 2 + socket 65
Wire resistance: Max. 1.5 Ohms
- Check wires for shorting to one another.
- Specification: Infinity Ohms
- Check wiring for open circuit between connector terminals 1 of fuel injectors.
- Wire resistance: Max. 1.5 Ohms
Fuel injector resistance, checking
- Check fuel injector resistance between connector terminals on the fuel injector.
- Specification: 12.0 to 15.0 Ohms
If specification not obtained
- Replace faulty fuel injector
Fuel injection leak checking and delivery rate, checking
Test conditions
- Fuel pressure must be within specification range, Testing and Inspection, checking
- Disconnect harness connector from all injectors.
- Remove fuel rail assembly.
- Disconnect vacuum hose from fuel pressure regulator.
- Lift fuel rail (complete with injectors) off of intake manifold and support as required.
Leak-checking
- Perform Output Diagnostic Test Mode (DTM) and activate cyl. 1 Fuel injector N30, Refer to "Computers and Control Systems", [1][2][3]Output Diagnostic Test Mode (DTM) (Function 03)
- Fuel pump must run
NOTE:
This work sequence allows the fuel pump to run when the engine is not running. Closed Throttle Position switch must remain closed during this check, otherwise selected injector will inject 5 times.
- Visually check injector for leaks
- Only 1 to 2 drops per minute, per injector with fuel pump running
If fuel leakage is greater than specification
- Switch OFF ignition and replace that injector.
- Always replace seals
Fuel injection quantity, checking
- Insert injector to be checked in VAG 1602 fuel analyzer tube.
- Connect one terminal of injector to be tested to engine Ground using jumper wires from VW 1594 adaptor kit.
Connect other injector terminal and jumper wire to VAG 1348/3A remote control using VAG 1348/3-2 adaptor cable . Connect crocodile clip to Battery .
Perform Output Diagnostic Test Mode (DTM) and activate cyl.1 injector N30, Refer to "Computers and Control Systems", [1][2][3]Output Diagnostic Test Mode (DTM) (Function 03)
- Fuel pump must run
- Operate VAG 1348/3A Remote control for 30 seconds.
- Repeat check on remaining injectors using new measuring tubes
- After all injectors have been activated, place measuring tubes on horizontal surface and compare injected quantities.
- Specification: 110 to 130 ml per injector
If the measured values of one or more injectors are above or below the prescribed specifications:
- Replace faulty injector.
Perform fuel injector installation in reverse order.
- Replace O-rings on all injectors and lightly moisten with clean oil.
- Insert injectors vertically and in correct position into fuel rail and secure with retaining clips.
- Install fuel rail assembly onto intake manifold and press in evenly.