Subject:
Engine Knocking
Vehicles:
Omega - A / Carlton and Frontera with 23DTR engine
Condition:
Cases of engine knock at 1000 to 2000 rpm have been reported, in which incorrect operation of the fuel injector has been isolated as the cause.
Typically such injectors exhibit coking up of the nozzle. This results in a defective spray pattern.
In cases of engine knock in the above range, fuel injectors should be checked and if necessary serviced in accordance with the following instructions.
Note:
It is essential that new corrugated washers and copper sealing washers are installed. Ensure that the new corrugated washer is correctly aligned as given on page 3
Checking the spray pattern
Before testing, clean the injector externally. Prevent dirt from entering into the pipe connections.
After connecting the injector to a injector tester, operate the pump lever several times to expel air from the system.
If the result of any of the following tests is unsatisfactory, the injector must be disassembled and cleaned, repaired or replaced.
| To check the spray pattern, isolate the pressure gauge and operate the pump lever quickly (4 to 6 strokes per second). The jet of fuel should emerge in the form of a narrow cone, without any scatter. | |||
|---|---|---|---|
| .P. U5905.tif | 9 | 7,5 | tiff;; |
To check the seat tightness wipe the nozzle face dry and operate the pump lever to produce a pressure of 100 bars. The nozzle is serviceable if no fuel drops form within 1 0 seconds; a slight dampness may be ignored.
| To correct the spray pattern and / or rectify leakage, disassemble injector, ensure that nozzle and needle are kept in their matched pairs. Clean ail parts in test fluid using a soft wooden spatula to remove any carbon. Do not attempt to lap the injector needle to the nozzle seating. Before reassembly check that the injector needle can fall freely under its own weight in the nozzle. | |||
|---|---|---|---|
| .P. A7047.tif | 9 | 7,5 | tiff;; |
Checking the delivery pressure
To check the delivery pressure, restore the gauge to the circuit and operate the pump lever (once per second) until fuel issues from the nozzle. This should occur at 135 bar.
To reset delivery pressure, disassemble the injector and adjust the thickness of the spring shims. These are available in the range 1.0 mm to 1.95 mm in increments of 0.05 mm. A shim thickness difference of 0.05 mm represents a pressure difference of approximately 5 bar.
| On reassembly, tighten the nozzle cap in the nozzle holder to a torque of 80 Nm. | |||
|---|---|---|---|
| .P. U5906.tif | 9 | 7,5 | tiff;; |
Install a corrugated washer into the injector heat protection sleeve. Ensure that the new washer is correctly aligned as shown in U5907.
Install a new copper sealing washer on the flange of the injector heat protection sleeve.
| Refit injectors to cylinder head and tighten to 70 Nm. | |||
|---|---|---|---|
| .P. U5907.tif | 9 | 7,5 | tiff;; |
Parts
Description Part No. Cat. No
Copper Sealing Ring 3 456 256 8 21 203
Corrugated Washer 3 456 258 8 21 701
Time Allowance
The published time allowances are not affected.
All future literature will be amended accordingly.