Inspection Procedure 18
Inspection procedure 18: Transient, mass emission tailpipe test failureCOMMENT
- The test is failed when the air/fuel ratio is not controlled to the ideal air/fuel ratio. This occurs due to the feedback control by heated oxygen sensor signals, or deteriorated catalyst.
NOTE: If the three-way catalyst temperature is low when checking the exhaust gas, the three-way catalyst can not sufficiently clean the emissions. Warm up the engine sufficiently before checking the exhaust, and check immediately.
TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Malfunction of air/fuel ratio control system.
- Malfunction of the fuel pump system.
- Malfunction of the ignition system.
- Poor compression.
- Improper operation of the PCV valve
- Malfunction of the evaporative emission control system
- Deteriorated catalyst.
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 the exhaust gas with the engine at normal operating temperature.
Q: Was the exhaust gas checked with engine warmed sufficiently?
YES : Go to Step 2.
NO : Check it again after enough warm up.
STEP 2. Check the following items.
1. Check the following items.
a. Check all vacuum hoses and connectors.
b. Check electrical wires and connectors for obvious problems.
Q: Are they normal?
YES : Go to Step 3.
NO : Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 3. Check the driveability.
Q: Is the driveability normal?
YES : Go to Step 4.
NO : Refer to Trouble Symptom Chart. Symptom Chart
STEP 4. 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 to the "LOCK" (OFF) position.
Q: Is any DTC set?
YES : Refer to Diagnostic Trouble Code Chart. Diagnostic Trouble Code Descriptions
NO : Go to Step 5.
STEP 5. Check the ignition timing.
Q: Is the ignition timing normal?
YES : Go to Step 6.
NO : Check that the crankshaft position sensor and timing chain case are in the correct position. Then confirm that the malfunction symptom is eliminated.
STEP 6. 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. Datal List Reference Table
a. Item 5: Intake Air Temperature Sensor.
b. Item 6: Engine Coolant Temperature Sensor.
c. Item AC: Heated Oxygen Sensor (front)
d. Item BB: Barometric Pressure Sensor
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are they operating properly?
YES : Go to Step 7.
NO : Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 7. Using scan tool MB991958, check data list item AD: Heated oxygen sensor (rear).
1. Start the engine and run at idle.
2. Set scan tool MB991958 to the data reading mode for item AD, Heated Oxygen Sensor (rear).
a. Transaxle: 2nd
b. Drive with wide open throttle
c. Engine: 3,500 r/min
- The output voltages should be between 0.6 and 1.0 volt.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES : Go to Step 8.
NO : Refer to, P0137 - Heated Oxygen Sensor (rear) Circuit Low Voltage, P0137 DTC P0138 - Heated Oxygen Sensor (rear) Circuit High Voltage, P0138 DTC P0139 - Heated Oxygen Sensor (rear) Circuit Slow Response, P0139 DTC P0140 - Heated Oxygen Sensor (rear) Circuit No Activity Detected. P0140
STEP 8. Check the fuel pressure.
Q: Is the fuel pressure normal?
YES : Go to Step 9.
NO : Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 9. 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 10.
STEP 10. 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 11.
STEP 11. Check the compression pressure.
Q: Is the compression pressure normal?
YES : Go to Step 12.
NO : Repair it. Then confirm that the malfunction symptom is eliminated.
STEP 12. Check the positive crankcase ventilation system.
Q: Is the positive crankcase ventilation system,?
YES : Go to Step 13.
NO : Repair it. Then confirm that the malfunction symptom is eliminated.
STEP 13. Check the evaporative emission control system.
Q: Is the purge control system normal?
YES : Go to Step 14.
NO : Repair it. Then confirm that the malfunction symptom is eliminated.
STEP 14. Check the following items.
1. Check the following items.
a. Check the injectors for fuel leakage.
b. Check if the injectors are clogged.
Q: Are there any abnormalities?
YES : Replace it. Then confirm that the malfunction symptom is eliminated.
Then confirm that the malfunction symptom is eliminated.
NO : Replace the catalytic converter. Then confirm that the malfunction symptom is eliminated.