Inspection Procedure 6
Inspection procedure 6: Hard startingCOMMENT
- In cases such as the above, the cause is usually either weak spark, improper air-fuel mixture or low compression.
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.
- 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 the "LOCK" (OFF) position.
Q: Is any 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 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 the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES : Go to Step 3.
NO : Repair or replace. 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. Then confirm that the malfunction symptom is eliminated.
STEP 4. Check the ignition timing.
Q: Is the ignition timing normal?
YES : Go to Step 5.
NO : Repair or replace. Then confirm that the malfunction symptom is eliminated.
STEP 5. Check the fuel pressure.
Q: Is the fuel pressure normal?
YES : Go to Step 6.
NO : Repair or replace. Then confirm that the malfunction symptom is eliminated.
STEP 6. 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 7.
NO : Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 7. 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 8.
NO : Replace the faulty injector. Then confirm that the malfunction symptom is eliminated.
STEP 8. Check harness connector A-25X at injector relay for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 9.
NO : Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 9. 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 10.
NO : Repair it. Then confirm that the malfunction symptom is eliminated.
STEP 10. Check harness connector B-09 at ECM for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 11.
NO : Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 11. Check for open circuit and short circuit to ground and harness damage between injector connector and ECM connector.
a. No. 1 cylinder injector connector B-101 (terminal No. 2) and ECM connector B-09 (terminal No. 2).
b. No. 2 cylinder injector connector B-102 (terminal No. 2) and ECM connector B-09 (terminal No. 3).
c. No. 3 cylinder injector connector B-103 (terminal No. 2) and ECM connector B-09 (terminal No. 18).
d. No. 4 cylinder injector connector B-104 (terminal No. 2) and ECM connector B-09 (terminal No. 19).
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 ignition system.
1. Connect the timing light to terminal No. 4 of the ignition coil connector B-02, B-03, B-04 or B-06 in order.
2. Crank the engine.
- The timing light flashes.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Does the timing light flash?
YES : Go to Step 13.
NO : Refer to Inspection procedure 25 - Ignition circuit system. Inspection Procedure 25
STEP 13. 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 14.
STEP 14. Check the ignition coil.
Q: Are there any abnormalities?
YES : Replace the ignition coil. Then confirm that the malfunction symptom is eliminated.
NO : Go to Step 15.
STEP 15. Check the compression pressure.
Q: Is the compression pressure normal?
YES : Check the following items, and repair or replace the defective items.
a. Check if fuel is contaminated.
b. 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.