Astra L4-1.8L (2009)
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If the ECT sensor is not between 10-32°C (50-90°F), measure and record the resistance of each fuel injector with a DMM. Subtract the lowest
resistance value from the highest resistance value. The difference between the lowest value and the highest value should be equal to or less than 3
ohms.
‹› If the difference is equal to or less than 3 ohms, refer to Fuel Pressure Test for further diagnosis of the fuel injectors.
‹› If the difference is more than 3 ohms, add all of the fuel injector resistance values to obtain a total resistance value. Divide the total resistance
value by the number of fuel injectors to obtain an average resistance value. Subtract the lowest individual fuel injector resistance value from
the average resistance value. Compute the difference between the highest individual fuel injector resistance value and the average resistance
value. Replace the fuel injector that displays the greatest difference above or below the average.
Fuel Pressure Test
Important:
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DO NOT perform the Fuel Pressure Test if the engine coolant temperature (ECT) is above 94°C (201°F). Irregular fuel pressure
readings may result due to hot soak fuel boiling.
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Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.
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Before proceeding with this test review the User Manual CH 48027-5 for Safety Information and Instructions.
1. Install a fuel pressure gage. Refer to Fuel Pressure Gage Installation and Removal (See: Fuel Filter/Fuel Pressure Release/Service and Repair).
2. Turn ON the ignition, with the engine OFF.
Important:
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The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.
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DO NOT start the engine.
3. Command the fuel pump relay ON with a scan tool.
4. Observe the fuel pressure gage with the fuel pump relay commanded ON. The fuel pressure should be 345-414 kPa (50-60 psi).
‹› If the fuel pressure is not 345-414 kPa (50-60 psi), refer to Fuel System Diagnosis (See: Computers and Control Systems/Testing and
Inspection/Component Tests and General Diagnostics/Fuel System Diagnosis).
5. Monitor the fuel pressure gage for five minutes. The fuel pressure should not decrease more than 34 kPa (5 psi).
‹› If the fuel pressure decreases more than 34 kPa (5 psi), refer to Fuel System Diagnosis (See: Computers and Control Systems/Testing and
Inspection/Component Tests and General Diagnostics/Fuel System Diagnosis).
6. Perform the Fuel Injector Balance Test.
Fuel Injector Balance Test
1. Set the selector switch on the fuel injector tester to the Balance Test 50 pulses/10 ms position.
2. Connect the SA9182E to a fuel injector.
3. Command the fuel pump relay ON and then OFF three times with a scan tool. On the last command, as the fuel pressure begins to slowly degrade
and stabilize, select a fuel pressure within 34 kPa (5 psi) of the maximum pump pressure. Record this fuel pressure. This is the starting pressure at
which you will pulse each injector.
4. Command the fuel pump relay ON one more time and energize the fuel injector by depressing the Activate Injector button on the SA9182E at the
previously selected pressure.
5. After the injector stops pulsing, select Min from the Display Mode and record the Min pressure.
Important: New test results will not be recorded if the Min/Max results are not cleared after each injector is tested.
6. Clear the Min/Max results.
7. Select Normal from the Display Mode.
8. Repeat steps 2 and 4 through 7 for each fuel injector.
9. Perform the Pressure Drop Calculation.
Pressure Drop Calculation
1. Subtract the minimum pressure from the starting pressure for one fuel injector. The result is the pressure drop value.
2. Obtain a pressure drop value for each fuel injector.
3. Add all of the individual pressure drop values except for the injector suspected of being faulty. This is the total pressure drop.
4. Divide the total pressure drop by the number of fuel injectors that were added together. This is the average pressure drop. The difference between
any individual pressure drop and the average pressure drop should not be more than 20 kPa (3 psi).
