Inspection Procedure 5
Inspection procedure 5: Starts up and diesCOMMENT
- In such cases as the above, the cause is usually improper air/fuel mixture. It is possible, though less likely, that the spark plugs are generating sparks but the sparks are weak.
TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Malfunction of the fuel pump system.
- Malfunction of the ignition system.
- Malfunction of the injector system.
- Poor compression.
- Contaminated fuel.
- Dirtiness around throttle valve.
- Malfunction of the ECM.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
STEP 1. Using scan tool MB991958, read the diagnostic trouble code (DTC).
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Read the DTC.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC set?
YES : Refer to Diagnostic Trouble Code Chart. Diagnostic Trouble Code Descriptions
NO : Go to Step 2.
STEP 2. Using scan tool MB991958, check data list.
1. Turn the ignition switch to the "ON" position.
2. Check the following items in the data list. Refer to Data List Reference Table. Datal List Reference Table
a. Item 1: Power Supply Voltage
b. Item 6: Engine Coolant Temperature Sensor
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES : Go to Step 3.
NO : Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 3. Using scan tool MB991958, check actuator test.
1. Turn the ignition switch to the "ON" position.
2. Check the following items in the actuator test. Refer to Actuator Test Reference Table. Actuator Test Reference Table
a. Item 9: Fuel Pump.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the actuator operating properly?
YES : Go to Step 4.
NO : Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 4. Inspection of throttle body (throttle valve area) for dirtiness.
Q: Is the throttle valve area dirty?
YES : Refer to Throttle Body (Throttle Valve Area) Cleaning.
NO : Go to Step 5.
STEP 5. Check the ignition timing.
Q: Is the ignition timing normal?
YES : Go to Step 6.
NO : Check for installed conditions of the timing chain. Then confirm that the malfunction symptom is eliminated.
STEP 6. Check the fuel pressure.
Q: Is the fuel pressure normal?
YES : Go to Step 7.
NO : Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 7. Check harness connector B-101, B-102, B-103, B-104 at injector for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 8.
NO : Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 8. Check the injector resistance.
1. Disconnect the left bank injector connector B-101, B-102, B-103, B-104.
2. Measure the resistance between each injector side connector terminal No. 1 and No. 2.
Standard value: 10.5 - 13.5 ohms [at 20° C (68° F)]
Q: Is the measured resistance between 10.5 and 13.5 ohms [at 20° C (68° F)]?
YES : Go to Step 9.
NO : Replace the faulty injector. Then confirm that the malfunction symptom is eliminated.
STEP 9. Check harness connector A-34X at MFI relay and harness connector A-25X at injector relay connector for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 10.
NO : Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 10. Check for harness damage between MFI relay connector A-34X (terminal No. 2) and injector relay connector A-25X (terminal No. 4).
Q: Is the harness wire in good condition?
YES : Go to Step 11.
NO : Repair it. Then confirm that the malfunction symptom is eliminated.
STEP 11. Check for harness damage between injector relay connector and injector connector.
NOTE: Check harness after checking intermediate connector A-39. If intermediate connector is damaged, repair or replace it. Then confirm that the malfunction symptom is eliminated.
a. Injector relay connector A-25X (terminal No. 3) and No. 1 cylinder injector connector B-101 (terminal No. 1).
b. Injector relay connector A-25X (terminal No. 3) and No. 2 cylinder injector connector B-102 (terminal No. 1).
c. Injector relay connector A-25X (terminal No. 3) and No. 3 cylinder injector connector B-103 (terminal No. 1).
d. Injector relay connector A-25X (terminal No. 3) and No. 4 cylinder injector connector B-104 (terminal No. 1).
Q: Is the harness wire in good condition?
YES : Go to Step 12.
NO : Repair it. Then confirm that the malfunction symptom is eliminated.
STEP 12. Check the spark plugs.
Q: Are there any abnormalities?
YES : Replace the spark plug. Then confirm that the malfunction symptom is eliminated.
NO : Go to Step 13.
STEP 13. Check the ignition coil.
1. Remove the intake manifold.
2. Refer to Ignition System - On-vehicle Service - Ignition Coil Check. Testing and Inspection
Q: Are there any abnormalities?
YES : Replace the ignition coil. Then confirm that the malfunction symptom is eliminated.
NO : Go to Step 14.
STEP 14. Check the compression pressure.
Q: Is the compression pressure normal?
YES : Check the following items, and repair or replace the defective items.
a. Check fuel lines for clogging.
b. Check if fuel is contaminated.
c. Check if the injectors are clogged.
Then confirm that the malfunction symptom is eliminated.
NO : Repair it. Then confirm that the malfunction symptom is eliminated.