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Inspection procedure 6: Hard starting
 
 
 
 
COMMENT
  • 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:)
  • Fuel pump system failed.
  • Ignition system failed.
  • Injector system failed.
  • Poor compression.
  • EGR system failed.
  • Contaminated fuel.
  • ECM failed.

 
 
DIAGNOSIS
Required Special Tool:
  • 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.
Is the initialization sound heard in the EGR valve?
Go to Step 2.
Refer to GROUP 17, Emission Control - Exhaust Gas Recirculation (EGR) System - EGR Valve (stepper motor) Check .
 
STEP 2. Using scan tool MB991958, read the diagnostic trouble code (DTC).
cautionTo 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.
Is any DTC set?
Refer to, Diagnostic Trouble Code Chart .
Go to Step 3.
 
STEP 3. 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 .
  1. Item 1: Power Supply Voltage
  2. Item 6: Engine Coolant Temperature Sensor
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the sensor operating properly?
Go to Step 4.
Repair or replace it. 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 item in the actuator test. Refer to Actuator Test Reference Table .
  1. Item 9: Fuel Pump
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the actuator operating properly?
Go to Step 5.
Repair or replace it. Then confirm that the malfunction symptom is eliminated.
 
STEP 5. Check the ignition timing.
Refer to GROUP 11A, On-vehicle Service - Ignition Timing Check .
Is the ignition timing normal?
Go to Step 6.
Repair or replace it. Then confirm that the malfunction symptom is eliminated.
 
STEP 6. Check the fuel pressure.
Refer to, Fuel Pressure Test .
Is the fuel pressure normal?
Go to Step 7.
Repair it. Then confirm that the malfunction symptom is eliminated.
 
STEP 7. Check harness connector B-101, B-102, B-105 and B-106 at injector for damage.
Are the harness connectors in good condition?
Go to Step 8.
Repair or replace them. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 8. Check the injector.
(1) Disconnect the injector connectors B-101, B-102, B-105 and B-106.
(2) Measure the resistance between each injector side connector terminal No. 1 and No. 2.
Standard value: 10.5 - 13.5 Ω [at 20°C (68°F)]
Is the measured resistance between 10.5 and 13.5 Ω [at 20°C (68°F)]?
Go to Step 9.
Replace the faulty injector. Then confirm that the malfunction symptom is eliminated.
 
STEP 9. Check harness connector A-70X at injector relay for damage.
Is the harness connector in good condition?
  • Go to Step 10.
Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 10. Check for harness damage between injector relay connector and injector connector.
noteCheck harness after checking intermediate connector A-17. If intermediate connector is damaged, repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
  1. Check the harness wire between injector relay connector A-70X (terminal No. 3) and injector connector B-101 (terminal No. 1) at No. 1 cylinder injector.
  2. Check the harness wire between injector relay connector A-70X (terminal No. 3) and injector connector B-102 (terminal No. 1) at No. 2 cylinder injector.
  3. Check the harness wire between injector relay connector A-70X (terminal No. 3) and injector connector B-105 (terminal No. 1) at No. 3 cylinder injector.
  4. Check the harness wire between injector relay connector A-70X (terminal No. 3) and injector connector B-106 (terminal No. 1) at No. 4 cylinder injector.
Are the harness wires in good condition?
Go to Step 11.
Repair them. Then confirm that the malfunction symptom is eliminated.
 
STEP 11. Check harness connector B-26 at ECM for damage.
Is the harness connector in good condition?
Go to Step 12.
Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 12. Check for open circuit, short circuit to ground and harness damage between injector connector and ECM connector.
  1. Check the harness wire between injector connector B-101 (terminal No. 2) and ECM connector B-26 (terminal No. 2) at No. 1 cylinder injector.
  2. Check the harness wire between injector connector B-102 (terminal No. 2) and ECM connector B-26 (terminal No. 3) at No. 2 cylinder injector.
  3. Check the harness wire between injector connector B-105 (terminal No. 2) and ECM connector B-26 (terminal No. 18) at No. 3 cylinder injector.
  4. Check the harness wire between injector connector B-106 (terminal No. 2) and ECM connector B-26 (terminal No. 19) at No. 4 cylinder injector.
Are the harness wires in good condition?
Go to Step 13.
Repair them. Then confirm that the malfunction symptom is eliminated.
 
STEP 13. Check the ignition system.
(1) Connect the timing light to terminal No. 3 of the ignition coil connectors B-21, B-22, B-23 or B-24 in order.
(2) Crank the engine.
  • The timing light flashes.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Does the timing light flash?
Go to Step 14.
Refer to, Inspection Procedure 25 - Ignition Circuit System .
 
STEP 14. Check the spark plugs.
Refer to GROUP 16, Ignition System - On-vehicle Service - Spark Plug Check and Cleaning .
Are there any abnormalities?
Replace the spark plug. Then confirm that the malfunction symptom is eliminated.
Go to Step 15.
 
STEP 15. Check the ignition coil.
Refer to GROUP 16, Ignition System - On-vehicle Service - Ignition Coil Check .
Are there any abnormalities?
Replace the ignition coil. Then confirm that the malfunction symptom is eliminated.
Go to Step 16.
 
STEP 16. Check the compression pressure.
Refer to GROUP 11A, On-vehicle Service - Compression Pressure Check .
Is the compression pressure normal?
  • Check the following items, and repair or replace the defective items.
    1. Check if fuel is contaminated.
    2. Check if the injectors are clogged.
  • Then confirm that the malfunction symptom is eliminated.
Repair it. Then confirm that the malfunction symptom is eliminated.