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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.
  • Contaminated fuel.
  • ECM failed.

 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
(1) Connect scan tool (M.U.T.-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(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 2.
 
STEP 2. Using scan tool (M.U.T.-III), 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 3.
Repair or replace it. Then confirm that the malfunction symptom is eliminated.
 
STEP 3. Using scan tool (M.U.T.-III), 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 4.
Repair or replace it. Then confirm that the malfunction symptom is eliminated.
 
STEP 4. Check the ignition timing.
Refer to GROUP 11A, On-vehicle Service - Ignition Timing Check .
Is the ignition timing normal?
Go to Step 5.
Repair or replace it. Then confirm that the malfunction symptom is eliminated.
 
STEP 5. Check the fuel pressure.
Refer to, Fuel Pressure Test .
Is the fuel pressure normal?
Go to Step 6.
Repair it. Then confirm that the malfunction symptom is eliminated.
 
STEP 6. Check the injector.
  • Injector check (Refer to ).
Is the measured resistance normal?
Go to Step 7.
Replace the faulty injector. Then confirm that the malfunction symptom is eliminated.
 
STEP 7. Check of harness damage in power supply line between MFI relay connector and injector connector.
Are the harness wires in good condition?
Go to Step 8.
Repair them. Then confirm that the malfunction symptom is eliminated.
 
STEP 8. Check of open circuit, short circuit to ground and harness damage in control line between injector connector and ECM connector.
Are the harness wires in good condition?
Go to Step 9.
Repair them. Then confirm that the malfunction symptom is eliminated.
 
STEP 9. Check the ignition system.
(1) Connect the timing light to terminal power supply line of the ignition coil connectors 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 10.
Refer to Inspection Procedure 26 - Ignition Circuit System .
 
STEP 10. 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 11.
 
STEP 11. 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 12.
 
STEP 12. 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.