With Manufacturer's Scan Tool

Fuel injection quantity and injector leakage, checking

Checking conditions
- Fuel pressure regulator OK, Testing and Inspection

Checking
- Remove intake air hose between MAF sensor and intake air elbow.




- Remove harness connectors -1- from all fuel injectors -2-.




- Disconnect fuel rail from intake manifold (arrows).
- Disconnect vacuum hose from intake Manifold Tuning (IMT) valve -N156- (change-over valve).
- Disconnect vacuum hose from fuel pressure regulator.
- Disconnect 5-pin connector from ignition coils, 2-pin connector from valve -2- for camshaft adjustment -N208- (bank 2) and 2-pin connector from Camshaft Position (CMP) sensor 2 -G163- (bank 1).
- Disconnect wiring harness from clips on fuel rail.
- Lift fuel rail with fuel injectors from intake manifold and support it above manifold.


Checking for leakage
- Conduct output DTM, actuating cylinder 1 fuel injector -N30-, (fuel pump must be running). [1][2][3]Output Diagnostic Test Mode (DTM) (Function 03)

NOTE: This step lets the fuel pump run without the engine running. The closed throttle position switch must be closed during the test, or the selected fuel injector will be activated 5 times, discharging fuel.

- Visually check fuel injector for leaks.

With fuel pump running, only 1 to 2 drops can drip per minute (per injector).

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

NOTE: Always replace seals.


Checking injection quantity




- Insert fuel injector to be tested into measuring glass of VAG1602 fuel analyzer.
- Connect one terminal of fuel injector being tested to engine Ground using test lead from VAG1594.




- Connect second terminal of fuel injector to B+ using VAG1348/3A remote control, VAG1348/3-2 adapter wire and an auxiliary wire.
- Connect alligator clip to battery positive (B+) terminal.
- Conduct output DTM, actuating cylinder 1 fuel injector -N30-, (fuel pump must be running). [1][2][3]Output Diagnostic Test Mode (DTM) (Function 03)
- Operate remote VAG1348/3A for 30 seconds.
- Repeat check for other fuel injectors on cylinder bank. Use separate measuring containers.
- After all three fuel injectors on one cylinder bank have been activated, place three measuring containers on level surface and compare injected quantities.
Specified volume per injector: 90-125 ml (3.04-4.2 fl oz)

If the measured volume of one or more fuel injectors is below or above the specified volume:
- Replace malfunctioning fuel injector.
- Repeat test on fuel injectors in second bank of cylinders.
- Install fuel injectors in reverse order of removal.

NOTE:
When doing this note the following:
- Replace O-rings on all fuel injectors and coat O-rings lightly with clean engine oil.
- Slide fuel injectors (vertically) into position in fuel rail and secure injectors with retaining clips.
- Place fuel rail together with secured fuel injectors on manifold and press fuel rail and secured injectors in evenly.