With Manufacturer's Scan Tool

Checking Injection Quantity and Proper Seal of Fuel Injectors

Special tools and equipment






- VAG 1348/3 remote control
- VAG 1348/3-2 adapter
- VAG 1602 tester for quantity of injected fuel

Test condition

- Fuel pressure must be working properly, testing. Testing and Inspection

WARNING!
Fuel system is under pressure! Before opening the fuel system, place rags under and around the connection then slowly release the fuel pressure.

Test sequence

- Remove suction hose between Mass Air Flow (MAF) sensor and intake air scoop.






- Pull connectors (1) off connection (2) of all fuel injectors.






- Unscrew fuel rail from intake manifold (arrows).
- Pull vacuum hose off fuel pressure regulator.
- Lift fuel rail with fuel injectors off intake manifold and support it.

Checking Proper Seal

- Perform output Diagnostic Test Mode (DTM); transfer Fuel Pump (FP) must be running. Refer to Scan Tool Testing/Output Diagnostic Test Mode (DTM) [1][2]Output Diagnostic Test Mode (DTM), (Function 03)

NOTE: The only purpose of this step is to allow the transfer Fuel Pump (FP) to run with the engine stationary.

- Check proper seal of fuel injectors (visual inspection). With transfer Fuel Pump (FP) running, only 1 to 2 drops per minute should escape from each valve.

If fuel loss is greater:
- Switch off ignition and replace leaking fuel injector.

NOTE: Always use new sealing rings.

Checking Injection Quantity






- Place a fuel injector to be tested into a graduated measuring glass of tester for quantity of injected fuel VAG 1602.






- Use auxiliary wires from VAG 1594 to connect one terminal of tested fuel injector to engine Ground (GND).
- Use auxiliary wire to connect second terminal of fuel injector to remote control VAG 1348/3 with adapter wire VAG 1348/3-2.
- Connect alligator clip to B+.
- Perform output Diagnostic Test Mode (DTM) again; transfer Fuel Pump (FP) must be running. [1][2]Output Diagnostic Test Mode (DTM), (Function 03)
- Operate remote control VAG 1348/3 30 for 30 seconds.
- Repeat test on other fuel injectors. Use new graduated measuring glasses for this.

- After all fuel injectors have been activated, place graduated measuring glasses on a level surface and compare quantity of injected fuel.
Specification: 90-125 ml. per injector

If the measured value of one or more fuel injectors is below or above the indicated expected value:

NOTE: Also check spray pattern when checking injection quantity. Spray pattern must be the same for all injectors

- Switch ignition off.
- Replace faulty fuel injector.

Installation of fuel injectors is the same in reverse order. Note the following:
- Replace O-rings on all fuel injectors and wet them slightly with clean motor oil.
- Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining clips.
- Place fuel rail with secured fuel injectors onto intake manifold, and apply uniform pressure to press it in.