Open Fuel Injectors, Checking

Open injector means: the nozzle needle does not close all of the way and fuel leaks into the cylinder.

Special tools and workshop equipment required

Hand Vacuum PumpVAS6213
Make an -adapter- for the return line.

Fig 1: Hand Vacuum Pump
Courtesy of AUDI OF AMERICA, LLC

Procedure

-- Remove the engine cover. Refer to ENGINE COVER, REMOVING AND INSTALLING .

-- Clean all fuel rail connections with engine or brake cleaner and dry off.

WARNING:

Observe the instructions for all work on the fuel injectors. Refer to CLEAN WORKING CONDITIONS AND FUEL SYSTEM WORK INSTRUCTIONS .

Always follow these instructions before and during work.

Check One Cylinder After Another

Starting with cylinder 1.

-- Remove the fuel supply hoses from the fuel injectors by pressing both retaining straps down while pulling up on the center piece to release in direction of -arrow-.

Fig 2: Removing Fuel Supply Hoses From Fuel Injectors

Courtesy of AUDI OF AMERICA, LLC

NOTE:

The illustration shows cylinder bank 1.

-- Connect the clean adapter that has been cleaned out using compressed air to the fuel return line connection on the injector that is being checked.

-- A vacuum pressure of -500 mbar (-7.25 psi) is applied using the Hand Vacuum PumpVAS6213.

Fuel injectors are OK when the pressure remains constant for about 30 seconds.

If an injector is faulty, then the pressure will drop to 0 bar again within 2 to 3 seconds.

Repeat the test if necessary. Watch the Hand Vacuum PumpVAS6213 for a loss of pressure.

-- Replace any defective fuel injectors. Refer to PIEZOELECTRIC FUEL INJECTORS, REMOVING AND INSTALLING .

Assembling

-- Inspect the O-ring for the fuel return line connection for damage and deformation.

Replace the O-ring if it is Damaged or Bent.

NOTE:

Lubricate all of the O-rings with assembly oil or engine oil before installing.

-- Carefully press the return line connections over the sealing rings and onto the fuel injectors. The connection must engage audibly. Then press the release pin down carefully.

Fuel System Leak Test

-- Let the engine run a few minutes at idle without pressing the accelerator pedal and then stop the engine. The fuel system bleeds itself.

-- Check the entire fuel supply system for leaks.

Replace any leaking parts.

-- Perform a road test where the accelerator pedal is pressed all the way down at least one time. Then check the high pressure area again for leaks.

-- Install the engine cover. Refer to ENGINE COVER, REMOVING AND INSTALLING .