Inspection Procedure 14
Inspection procedure 14: Hesitation, sag, stumble, poor acceleration or surgeCOMMENT
- Defective ignition system, abnormal air/fuel ratio, poor compression pressure, etc. are suspected.
TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Fuel pump system failed.
- Ignition system failed.
- Poor compression.
- Improper operation of the PCV valve.
- Turbocharger system failed.
- Vacuum leak.
- Clogged air cleaner.
- Clogged exhaust system.
- TC-SST system failed.
- ECM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
NOTE: To protect the TC-SST, the TC-SST-ECU outputs, into the ECM, the request signal to reduce the engine torque according to the operation condition. Based on the signal, the ECM closes the throttle valve, retards the ignition or carries out fuel cut. At that time, the engine output seems to temporarily reduce, but there is no malfunction.
STEP 1. 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 2.
STEP 2. Using scan tool MB991958, read the diagnostic trouble code (DTC).
NOTE: When the TC-SST has a malfunction, the TC-SST-ECU might output the request signal of reducing the engine torque in order to protect the TC-SST.
1. Turn the ignition switch to the "ON" position.
2. Read the TC-SST-DTC.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the TC-SST-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 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 Actuator Test Reference Table.
a. Item 1: Injector.
b. Item 20: Turbocharger Wastegate Solenoid
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are thy operating properly?
YES : Go to Step 4.
NO : Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 4. Check the intake air temperature sensor 2.
1. Disconnect the intake air temperature sensor 2 connector B-20.
2. Measure the resistance between intake air temperature sensor 2 side connector terminal No. 1 and No. 2.
- There should be continuity. (0.23 - 18 kohms)
Q: Is the measured resistance between 0.23 and 18 kohms?
YES : Go to Step 5.
NO : Replace the intake air temperature sensor 2. Then confirm that the malfunction symptom is eliminated.
STEP 5. Check the ignition timing.
Refer to On-vehicle Service - Ignition Timing Check. Testing and Inspection
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. 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 8: Manifold Absolute Pressure Sensor
d. Item 11: Accelerator Pedal Position Sensor (main)
e. Item 12: Accelerator Pedal Position Sensor (sub)
f. Item 13: Throttle Position Sensor (main)
g. Item 15: Throttle Position Sensor (sub)
h. 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. Check the fuel pressure.
Refer to Fuel Pressure Test Testing and Inspection.
Q: Is the fuel pressure normal?
YES : Go to Step 8.
NO : Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 8. Check the spark plugs.
Refer to On-vehicle Service - Spark Plug Check and Cleaning. 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 9.
STEP 9. Check the ignition coil.
Refer to 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 10.
STEP 10. Check the positive crankcase ventilation system.
Refer to Positive Crankcase Ventilation System Check. System Check
Q: Is the positive crankcase ventilation system normal?
YES : Check the following items, and repair or replace the defective items.
a. Vacuum leak.
b. Clogged air cleaner.
c. Check intake charge pressure.
d. Check intake charge pressure control system.
e. Clogged exhaust system.
f. Check if fuel is contaminated.
g. Check if the injectors are clogged.
h. Check compression pressure.
i. Check if the foreign materials (water, kerosene, etc.) got into fuel. Then confirm that the malfunction symptom is eliminated.
NO : Repair it. Then confirm that the malfunction symptom is eliminated.