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
- Malfunction of the EGR system [California]
- 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. Check if the EGR valve sounds during initialization.
NOTE: Excluding the vehicle with the specification for California, go to Step 2.
Q: Is the initialization sound heard in the EGR valve?
YES : Go to Step 2.
NO : Refer to Emission Control - EGR Valve (Stepper Motor) Check. [1][2]Component Tests and General Diagnostics
STEP 2. 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 3.
STEP 3. 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 01: Power Supply Voltage (at Cranking)
b. Item 06: Engine Coolant Temperature Sensor.
3. Turn the ignition switch the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES : Go to Step 4.
NO : Repair or Replace. Then confirm that the malfunction symptom is eliminated.
STEP 4. 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 09: Fuel Pump.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the actuator operating properly?
YES : Go to Step 5.
NO : Repair or Replace. Then confirm that the malfunction symptom is eliminated.
STEP 5. Check the ignition timing.
1. Check the ignition timing at cranking.
Standard value: 5° BTDC ± 3°
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.
Refer to Fuel Pressure Test. Testing and Inspection
Q: Is the fuel pressure normal?
YES : Go to Step 7.
NO : Check the following items, and repair or replace the defective items.
- Insufficient fuel pump discharge.
- Fuel pump filter clogged.
STEP 7. Check the injector.
1. Disconnect the 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 B-108 at ECM and 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 9.
NO : Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 9. Check for harness damage between injector connector and ECM connector.
1. Disconnect the injector connector and ECM connector.
2. Measure the resistance between injector connector and ECM connector.
a. Injector connector B-101 (terminal No. 2) and ECM connector B-108 (terminal No. 2) at No. 1 cylinder injector.
b. Injector connector B-102 (terminal No. 2) and ECM connector B-108 (terminal No. 3) at No. 2 cylinder injector.
c. Injector connector B-103 (terminal No. 2) and ECM connector B-108 (terminal No. 18) at No. 3 cylinder injector.
d. Injector connector B-104 (terminal No. 2) and ECM connector B-108 (terminal No. 19) at No. 4 cylinder injector.
Q: Is the measured resistance less than 2 ohms?
YES : Go to Step 10.
NO : Repair it. Then confirm that the malfunction symptom is eliminated.
STEP 10. Check the ignition system.
1. Connect the timing light to terminal No. 3 of the ignition coil connector B-01, B-02, B-03 or B-04 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 11.
NO : Refer to Inspection procedure 25 - Ignition circuit system. Inspection Procedure 25
STEP 11. Check the spark plugs.
Refer to Ignition System - On-vehicle service - Spark Plug Check. Testing and Inspection
Q: Are there any abnormalities?
YES : Replace the spark plug. Then confirm that the malfunction symptom is eliminated.
NO : Go to Step 12.
STEP 12. Check the ignition coil.
1. Remove the intake manifold.
2. Refer to Ignition System - On-vehicle service - Ignition Coil Check. Ignition Coil Check
Q: Are there any abnormalities?
YES : Replace the ignition coil. Then confirm that the malfunction symptom is eliminated.
NO : Go to Step 13.
STEP 13. Check the compression pressure.
Refer to On-vehicle service - Compression Pressure Check. Compression Check
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.