Inspection Procedure 19
COMMENT- Defective ignition system, abnormal air/fuel ratio, etc. are suspected.
TROUBLESHOOTING HINTS
The most likely causes for this case:
- Malfunction of the ignition system.
- Malfunction of air/fuel ratio control system.
- Malfunction of the EGR solenoid system.
DIAGNOSIS
Required Special Tool:
MB991502: Scan Tool (MUT-II)
CAUTION: To prevent damage to the scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.
STEP 1. Using scan tool MB991502, read the diagnostic trouble code (DTC).
If DTC is not output, go to Step 2.
If DTC is output, refer to Diagnostic Trouble Code Chart.
CAUTION: To prevent damage to the scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.
STEP 2. Using scan tool MB991502, check actuator test items 01, 02, 03, 04, 05, 06: Injector.
If the test items indicate a defect, go to Step 3.
If the test items do not indicate a defect, go to Step 6.
STEP 3. Check the power supply line at injector connectors A-70, A-71, A-72, A-73, A-74, A-75.
1. Disconnect connectors A-70, A-71, A-72, A-73, A-74, A-75 and measure at the harness side.
2. Turn the ignition switch "ON".
3. Measure current while connecting terminal 1 to ground via a 20-ohms resistor.
- Current should be 0.5 ampere or more.
4. Turn the ignition switch "OFF".
If 0.5 ampere or more, go to Step 4.
If less than 0.5 ampere, check intermediate connector A-04, and repair or replace if necessary. Refer to vehicle level Testing and Inspection. If intermediate connector A-04 is in good condition, repair the harness wire between MFI relay connector C-59 and injector connectors A-70, A-71, A-72, A-73, A-74, A-75. Then check that the malfunction is eliminated.
STEP 4. Check the circuits at PCM connector C-89.
1. Disconnect connector C-89 and measure at the harness side.
2. Disconnect PCM connector C-90. Using a jumper wire, connect terminal 49 to ground. Then operate the MFI relay.
3. Turn the ignition switch "ON".
4. Connect terminals 1, 2, 9, 10, 24, 25 to ground via a 20-ohms resistor to measure the current at each injector as follows:
Terminal 1 for the number 1 cylinder injector
Terminal 9 for the number 2 cylinder injector
Terminal 24 for the number 3 cylinder injector
Terminal 2 for the number 4 cylinder injector
Terminal 10 for the number 5 cylinder injector
Terminal 25 for the number 6 cylinder injector
- Current should be 0.3 ampere or more.
5. Turn the ignition switch "OFF".
If 0.3 ampere or more, go to Step 5.
If less than 0.3 ampere, check intermediate connector A-04. Repair or replace if necessary. Refer to vehicle level Testing and Inspection. If intermediate connector A-04 is in good condition, repair the harness wire between injector connectors A-70, A-71, A-72, A-73, A-74, A-75 and PCM connector C-89. Then check that the malfunction is eliminated.
STEP 5. Check harness connector C-89 at the PCM for damage.
If harness connector C-89 is in good condition, replace the injector.
If harness connector C-89 is damaged, repair or replace it. Refer to vehicle level Testing and Inspection.
Then check that the malfunction is eliminated.
STEP 6. Check the ignition timing.
Refer to On-vehicle Service <3.0L Engine>.
Refer to On-vehicle Service <3.5L Engine>.
If within specifications, go to Step 7.
If not within specifications, check that the crankshaft position sensor and timing belt cover are in the correct position. Then confirm that malfunction symptom is eliminated.
CAUTION: To prevent damage to the scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.
STEP 7. Using scan tool MB991502, check data list and actuator test.
1. Check the following items in the data list.
Refer to Data List Reference Table.
a. Item 26: Closed Throttle Position Switch <3.0L Engine>.
b. Item 13: Intake Air Temperature Sensor.
c. Item 25: Barometric pressure Sensor.
d. Item 21: Engine Coolant Temperature Sensor.
e. Item 14: Throttle Position Sensor.
f. Item 59: Heated Oxygen Sensor (rear)
g. Item 11: Heated Oxygen Sensor (front)
h. Item 69: Left Bank Heated Oxygen Sensor (rear)
i. Item 39: Left Bank Healed Oxygen Sensor (front)
2. Check the following items in the actuator test. Refer to Actuator Test Reference Table.
a. Item 10: EGR Solenoid.
If the checks above meet the specifications, go to Step 8.
If the checks above do not meet the specifications, repair or replace. Then confirm that the malfunction symptom is eliminated.
CAUTION: To prevent damage to the scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.
STEP 8. Using scan tool MB991502, check data list.
1. Check the following items of data list. Refer to Data List Reference Table.
a. Item 11: Heated Oxygen Sensor (front)
b. Item 39: Left Bank Heated Oxygen Sensor (front)
- Voltage should fluctuate between 0 - 0.4 volts and 0.6 - 1.0 volt while idling after the engine has been warmed.
If the voltage does not fluctuate, go to Step 9.
If the voltage fluctuates, go to Step 11.
STEP 9. Check the fuel pressure.
Refer to Fuel Pressure Test.
If correct, go to Step 10.
If incorrect, repair or replace. Then confirm that the malfunction symptom is eliminated.
STEP 10. Check the following items.
1. Check the following items, and repair or replace the defective items.
a. Vacuum leak.
- Broken intake manifold gasket.
- Broken air intake hose.
- Broken vacuum hose.
- Positive crankcase ventilation valve does not operate.
b. Injector clogged.
Then confirm that the malfunction symptom is eliminated.
STEP 11. Check the fuel pressure.
Refer to Fuel Pressure Test.
If correct, go to Step 12.
If incorrect, repair or replace. Then confirm that the malfunction symptom is eliminated.
STEP 12. Check the following items.
1. Check the following items, and repair or replace the defective items.
a. Check the ignition coil, spark plugs, spark plug cables.
b. Check the EGR system.
Then confirm that the malfunction symptom is eliminated.