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
- VW1594 connector test kit
- VAG1348/3A remote control connection
- VAG1348/3-2 adapter cable
- VAG1602 fuel analyzer
Test requirement
- Fuel pressure regulator OK.
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 -G163- (bank 1).
- Disconnect wiring harness from clips on fuel rail.
- Disconnect fuel rail from intake manifold and remove fuel lines together with injectors.
- 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 VAG1602 fuel analyzer.
- Connect one terminal of injector being tested to engine ground using test lead from VAG1594.
- Connect second terminal of injector to B+ using VAG1348/3A remote control, VAG1348/3-2 adapter wire and an auxiliary wire.
- Conduct output DTM, actuating cylinder 1 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 discharge fuel when it is actuated 5 times.
- Operate remote VAG1348/3A 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.
Checking for leaks
- Conduct output DTM, actuating cylinder 1 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 discharge fuel when it is actuated 5 times.
- 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.