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Inspection procedure 8: Too high CO and HC concentration
 
 
 
 
COMMENT
  • Abnormal air/fuel ratio is suspected.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this case:)
  • Fuel pump system failed.
  • Linear air-fuel ratio sensor failed.
  • Heated oxygen sensor (rear) failed.
  • Ignition system failed.
  • Poor compression.
  • EGR system failed.
  • Improper operation of the PCV valve.
  • Evaporative emission control system failed.
  • ECM failed.

 
 
DIAGNOSIS
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 (M.U.T.-IIISE), read the diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
(1) Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(2) Turn on the power supply mode of the electric motor switch.
(3) Read the DTC.
(4) Turn off the power supply mode of the electric motor switch.
Is any DTC set?
Refer to Diagnostic Trouble Code Chart .
Go to Step 3.
 
STEP 3. Check the ignition timing.
Refer to GROUP 11A, On-vehicle Service - Ignition Timing Check .
Is the ignition timing normal?
Go to Step 4.
Check for installed conditions of the timing chain. Then confirm that the malfunction symptom is eliminated.
 
STEP 4. Using scan tool (M.U.T.-IIISE), check data list.
(1) Turn on the power supply mode of the electric motor switch.
(2) Check the following items in the data list. Refer to Data List Reference Table .
  1. Item 5: Intake Air Temperature Sensor
  2. Item 6: Engine Coolant Temperature Sensor
  3. Item AD: Heated Oxygen Sensor (rear)
  4. Item E1: Linear Air-fuel Ratio Sensor
(3) Turn off the power supply mode of the electric motor switch.
Are they operating properly?
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 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 7.
 
STEP 7. 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 8.
 
STEP 8. Check the compression pressure.
Refer to GROUP 11A, On-vehicle Service - Compression Pressure Check .
Is the compression pressure normal?
Go to Step 9.
Repair it. Then confirm that the malfunction symptom is eliminated.
 
STEP 9. Check the positive crankcase ventilation system.
Refer to GROUP 17, Emission Control - Positive Crankcase Ventilation System - Crankcase Ventilation System Check .
Is the positive crankcase ventilation system normal?
Go to Step 10.
Repair it. Then confirm that the malfunction symptom is eliminated.
 
STEP 10. Check the evaporative emission control system.
Refer to GROUP 17, Emission Control - Evaporative Emission Control System - Evaporative Emission Control System Check (purge flow check) .
Is the evaporative emission control system normal?
  • Check the following item, and repair or replace the defective item.
    1. Check if the injectors are clogged.
  • Then confirm that the malfunction symptom is eliminated.
Repair it. Then confirm that the malfunction symptom is eliminated.