With Manufacturer's Scan Tool
Fuel Injectors, Checking
Special tools and equipment
- VAG 1551 Scan Tool or VAG 1552 with cable VAG 1551/3
- Test box VAG 1598/22
- Hand multimeter VAG 1526 or multimeter VAG 1715
- Diode test lamp VAG 1527
- Adapter set VAG 1594
- Wiring diagram
Check conditions
- Engine speed sensor must be OK, checking Testing and Inspection
- Fuel pump relay must be OK
- Fuses 28 and 32 must be 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.
Test sequence
- First check the activation of the injectors via Output Diagnostic Test Mode (DTM).
If one or more injectors do not click:
Checking activation and voltage supply
If injectors of cylinder No. 2 or 3 do not click:
- Remove intake manifold upper section.
- Pull connector off injector No. 2 or 3.
- Connect diode test lamp VAG 1527 using auxiliary cables from VAG 1594 to connector contacts of Cyl. 3.
- Operate starter and check the voltage supply for No. 3 cylinder injector.
The LED must flicker
- Repeat check at injector connector for No. 2 cylinder.
If injectors of cylinder No. 1 or 4 do not click:
- Pull connector off injector No. 1 or 4.
- Connect diode test lamp VAG 1527 using auxiliary cables from VAG 1594 to connector contacts of Cyl. 1.
- Operate starter and check voltage supply for No.1 cylinder injector.
The LED must flicker
- Repeat check at injector connector for No. 4 cylinder.
- Switch ignition off.
If the LED does not flicker on any cylinder:
- Connect diode test lamp to Cyl. 1 connector, contact 1 and Ground.
- Initiate Output Diagnostic Test Mode (DTM) again and activate No. 1 cylinder injector.
The LED must light up
- Repeat check at injector connectors for Cyls. 2 through 4.
If the LED does not light up:
- Switch ignition off.
- Check wire between 2 pin connector contact 1 and fuel pump (FP) relay -J17- for open circuit using wiring diagram.
Wire resistance: max. 1.5 Ohm
If the LED flickers on one or several cylinders:
- Connect test box VAG 1598/22 to control module wiring harness.
- Check wiring between test box and connector for open circuit according to wiring diagram.
Injector 1: Contact 2 + socket 73
Injector 2: Contact 2 + socket 80
Injector 3: Contact 2 + socket 58
Injector 4: Contact 2 + socket 65
Wire resistance: Max.1.5 Ohm
- Check additional wires for short to one another.
Specification: Infinite Ohm
- Check wiring for open circuit between injectors (contact 1) using wiring diagram.
Wire resistance: max. 1.5 Ohm
- If no malfunction is found in activation or voltage supply, check resistance of injectors.
Checking resistance of injectors
- Check resistance of injector between contacts.
Specification: 14 to 18 Ohm
NOTE: The resistance figures are valid for approx. 20 degree C. At higher temperatures the resistance figures will increase.
If the specification is not attained:
- Replace faulty injector
Check Injectors For Leaks And Quantity Injected
Special tools and equipment
- VAG 1348/3 Remote control
- VAG 1348/3-2 Adapter
- VAG 1602 Calibration tester
Test conditions
- The fuel pressure must be in order, checking Testing and Inspection.
WARNING: Fuel system is under pressure! Before opening the system place a cloth around the connection. Then release pressure by carefully loosening the connection.
Test sequence
- Remove intake manifold upper section.
- Pull connector off all injectors.
- Remove fuel rail securing bolts.
- Pull off vacuum hose from fuel pressure regulator.
- Lift fuel rail with injectors off intake manifold and support it.
Checking for leaks
- Initiate Output Diagnostic Test Mode (DTM) and activate cylinder 1 fuel injector -N30- ; fuel pump must run.
NOTE: This work sequence allows the fuel pump to run when the engine is not running. The idle speed switch must remain closed for this check, otherwise the selected injector will inject 5 times. Check injector for leaks (visual check).
- Check injector for leaks (visual check). Only 1 to 2 drops per minute must emit from each valve when fuel pump is running.
If the fuel loss is greater:
- Switch ignition off and replace leaking injector.
NOTE: Always replace seals.
Checking injected quantity
- Insert injector to be checked in a measuring glass of tester for injected quantity VAG 1602.
- Connect one contact of the injector to be tested to engine Ground using auxiliary cables from VAG 1594.
- Connect second injector contact with auxiliary cable to remote control VAG 1348/3 using adapter cable VAG 1348/3-2.
- Connect alligator clip to battery positive (+).
- Initiate Output Diagnostic Test Mode (DTM) and activate cylinder 1 fuel injector -N30-; fuel pump must run.
- Operate remote control VAG 1348/3 for 30 seconds.
- Repeat check on other injectors. To do this use new measuring beakers.
- After all injectors have been activated, place measuring containers on a level surface and compare quantity injected.
Specification: 85 to 105 ml. per injector
NOTE: If the measured values of one or more injectors are above or below the prescribed specifications:
- Replace faulty injector.
Perform installation of injectors in reverse order. When doing this note the following:
- Replace O-rings on all injectors and lightly moisten with clean engine oil.
- Insert injectors vertically and in the correct position into the fuel rail and secure with retaining clips.
- Install fuel rail with secured injectors onto intake manifold and press in evenly.