Injection Quantity, Leakage and Spray Pattern of Fuel Injectors

Injection Quantity, Freedom From Leaks And Spray Pattern Of Injectors, Checking

Condition
- Fuel pressure OK
- Remove fuel rail with injectors. Leave fuel hoses connected.

Checking injectors for leaks







- Hold injector to be tested over graduated beaker of injection quantity tester V.A.G 1602.
- Connect test box V.A.G 1598/31 at wiring harness to engine control module. Actual engine control module is not to be connected. Wiring And Component Check Using Test Box V.A.G 1598/31
- Use wires from adapter set V.A.G 1594 A to jumper contacts 1 and 65 at test box (this step connects Ground to one end of fuel pump relay coil).
- Switch on ignition.

NOTE:
- After switching on the ignition, the two fuel pumps are constantly in operation even if engine is not running. Reason: Fuel pump relay receives positive supply via central electrics unit after switching on the ignition. Ground is applied to the fuel pump relay via cable link in test box.
- Voltage is not applied directly to the fuel pumps by the fuel pump relay, however, but rather to a fuel pump control module (refer to exploded view of component locations). From there the voltage is then supplied to the two fuel pumps. At idle and in mid part throttle range, both fuel pumps are supplied with 10 V. In the upper part throttle range and at full throttle the two pumps are supplied with battery voltage.

- Check injectors for leaks (visual inspection).
With fuel pump running, only 1...2 drops per minute per injector may emerge.

If fuel loss is greater:
- Shut off fuel pump (switch off ignition) and replace faulty injector.

Checking injection quantity
- Hold injector to be tested over graduated beaker of, for example, injection quantity tester V.A.G 1602.

NOTE: Graduated beaker should have a capacity of at least 210 ml as upper injector tolerance is 203 ml.







- Connect one contact of injector to engine Ground using test lead and alligator clamp from V.A.G 1594 A.
- Connect second contact of injector to positive with remote control V.A.G 1348/3A, adapter lead V.A.G 1348/3-2 and test lead.
- Switch on ignition.
- Fuel pump must run

- Operate remote control V.A.G 1348/3A for 30 seconds.
- Perform measurement with all injectors.
Specification for each injector: 187 ... 203 ml

If reading does not match specification for all injectors:
- Check fuel pressure.

If reading does not match specification for one injector:
- Replace appropriate injector.

NOTE: Spray pattern is also to be checked when checking injection quantity. It must be the same for all injectors.

Install fuel rail with injectors in reverse order of removal. Pay attention to the following:
- Replace O-rings at all joints opened.
- Moisten O-rings with fresh engine oil.
- Make sure injectors are installed in correct position.
- Make sure clips are properly connected.
- Position fuel rail with secured injectors at intake manifold and press in evenly.

Tightening torque

Component Nm
Fuel rail to intake manifold 10