Fuel Injectors, Checking For Leakage

Fuel injectors, checking for leakage

WARNING!
Fire hazard! Do not smoke, work near heaters or open flame, or have anything nearby that could ignite fuel. The fuel system is under pressure. Before opening, cover connections with a rag, and open carefully to release pressure.

Required special tools and test equipment
- VW 1594 connector test kit
- VAG 1348/3A remote control connection
- VAG 1348/3-2 adapter cable
- VAG 16O2 fuel analyzer

Test requirement
Fuel pressure regulator OK Testing and Inspection

Checking
- Remove intake air hose between MAF sensor and intake air noise muffler.
- Remove vacuum hose from Intake Manifold Tuning (IMT) valve -N156- (change-over valve).
- Remove 5-pin connector from ignition coils, 2-pin connector from valve for camshaft adjustment -N208- (bank 2) and 2-pin connector from camshaft position sensor 2 -G163- (bank 1).
- Disconnect wiring harness from clips on fuel rail.







- Disconnect fuel rail from intake manifold and remove fuel lines together with injectors (arrows).
- Remove vacuum hose from fuel pressure regulator.
- Remove harness connectors from all injectors.


Checking injection amount







- Insert injector to be tested into measuring glass of VAG 1602 fuel analyzer.
- Connect one terminal of injector being tested to engine ground using test lead from VAG 1594.







- Connect second terminal of injector to B+ using VAG 1348/3A remote control, VAG 1348/3-2 adapter wire and an auxiliary wire.
- Conduct output DTM, actuating cylinder 1 fuel injector -N30- (fuel pump must be running).Refer to "Scan Tool Testing/Output Diagnostic Test Mode (DTM) (Function 03)" Testing and Inspection

NOTE: This step lets the fuel pump run without the engine running.

- Operate remote VAG 1348/3A for 30 seconds.


NOTE: The spray pattern must be the same for all valves.


Once all three injectors in a single bank have been checked:
- Place three measuring glasses on even surface and check volume.
Specified volume per injector: 90-125 ml

If the measured volume of one or more injectors is below or above the specified volume:
- Replace malfunctioning injector.
- Repeat test to injectors in second bank of cylinders.

If the measured volumes for all injectors are under or over the specified volume:
- Check fuel pressure. Testing and Inspection

Checking for leaks
- Conduct output DTM, actuating cylinder 1 fuel injector -N30- (fuel pump must be running).

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 injector for leaks.

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

If fuel loss is greater:
- Replace leaking injector.

Installation of the injectors is in reverse order of removal.

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