Inspection Procedure 15
INSPECTION PROCEDURE 15: Hesitation, Sag or StumbleCOMMENT
- In cases such as the above, the ignition system, air/fuel mixture or compression pressure may be defective.
TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Malfunction of the ignition system.
- Malfunction of air/fuel ratio control system.
- Malfunction of the fuel supply system.
- Malfunction of the EGR vacuum regulator solenoid valve system.
- Poor compression pressure.
- Malfunction of turbocharger system.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B
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 DTC set?
YES: Refer to, Diagnostic Trouble Code Chart. Diagnostic Trouble Code Descriptions
NO: Go to Step 2.
STEP 2. Using scan tool MB991958, check actuator test items 01, 02, 03, 04: Injector.
1. Check following items in the actuator test. Refer to, Actuator Test Reference Table. Actuator Test Reference Table
a. Items 01, 02, 03, 04: Injector.
2. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are the actuators operating properly?
YES: Go to Step 3.
NO: Refer to, DTC P0201, P0202, P0203, P0204 - Injector Circuit. P0201
STEP 3. Check the ignition timing.
1. Refer to, On-vehicle Service - Ignition Timing Check in Ignition Timing.
Q: Is the ignition timing normal?
YES: Go to Step 4.
NO: Check that the crankshaft position sensor and timing belt cover are in the correct position. Then confirm that the malfunction symptom is eliminated.
STEP 4. Using scan tool MB991958, check data list.
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. Check the following items in the data list. Refer to, Data List Reference Table. Data List Reference Table & Normal Scan Data Values
a. Item 13: Intake Air Temperature Sensor.
b. Item 25: Barometric pressure Sensor.
c. Item 21: Engine Coolant Temperature Sensor.
d. Item 14: Throttle Position Sensor.
e. Item 59: Heated Oxygen Sensor (rear).
f. Item 11: Heated Oxygen Sensor (front).
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are they operating properly?
YES: Go to Step 5.
NO: Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 5. Using scan tool MB991958, check actuator test.
1. Turn the ignition switch to the "ON" position.
2. Check the following items in the actuator test. Refer to, Actuator Test Reference Table. Actuator Test Reference Table
a. Item 10: EGR Vacuum Regulator Solenoid Valve.
b. Item 09: Fuel pressure solenoid.
c. Item 12: Turbocharger wastegate solenoid.
d. Item 13: Fuel pump relay 3.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are they actuator operating properly?
YES: Go to Step 6.
NO: Repair or replace it. 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 of data list. Refer to, Data List Reference Table. Data List Reference Table & Normal Scan Data Values
a. Item 11: Heated Oxygen Sensor (front).
- Voltage should fluctuate between 0 - 0.4 volt and 0.6 - 1.0 volt while idling after the engine has warmed-up.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES: Go to Step 8.
NO: Go to Step 7.
STEP 7. Check the fuel pressure.
Refer to On-vehicle Service-Fuel Pressure Test. Testing and Inspection
Q: Is the fuel pressure normal?
YES: Check the following items, and repair or replace the defective items.
a. Vacuum leak.
- Broken intake manifold gasket.
- Broken air intake hose.
- Broken vacuum hose.
- Positive crankcase ventilation valve does not operate.
b. Injector clogged.
Then confirm that the malfunction symptom is eliminated.
NO: Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 8. Check the fuel pressure.
Refer to On-vehicle Service-Fuel Pressure Test. Testing and Inspection
Q: Is the fuel pressure normal?
YES: Check the following items, and repair or replace the defective items.
a. Check the ignition coil, spark plugs and spark plug cables.
b. Check supercharging pressure.
c. Check intake charge pressure control system.
d. Check rotating resistance of turbocharger turbine wheel. (Does the wheel rotate smoothly?)
e. Check the EGR system.
f. Check compression pressure.
g. Check the fuel filter or fuel line for clogging.
Then confirm that the malfunction symptom is eliminated.
NO: Repair or replace it. Then confirm that the malfunction symptom is eliminated.