Inspection Procedure 18
COMMENT- Defective ignition system, abnormal air/fuel ratio, poor compression pressure, etc. are suspected.
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.
- Poor acceleration.
- Clogged exhaust system.
DIAGNOSIS
Required Special Tool:
MB991502: Scan Tool (MUT-II)
CAUTION: To prevent damage to the scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.
STEP 1. Using scan tool MB991502, read the diagnostic trouble code (DTC).
If DTC is not output, go to Step 2.
If DTC is output, go to Trouble Code Diagnostic Procedures.
STEP 2. Check the injector for operation sound.
1. Using a stethoscope or long blade screwdriver, check the operation sound ("tick-tick-tick") of injectors during idling or during cranking.
- An operation sound should be heard. If a sound is heard, go to Step 3.
If no sound is heard, refer to DTC P0201, P0202, P0203, P0204 - Injector Circuit Malfunction.
STEP 3. Check the ignition timing.
Refer to On-vehicle Service.
If within specifications, go to Step 4.
If not within specifications, check and repair the crankshaft position sensor check that the timing belt cover is in the correct position. Then confirm that the malfunction symptom is eliminated.
CAUTION: To prevent damage to the scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.
STEP 4. Using scan tool MB991502, check data list and actuator test.
1. Check the following items in the data list.
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).
2. Check the following items in the actuator test.
a. Item 10: EGR Solenoid.
If the checks above meet the specifications, go to Step 5. If the checks above do not meet the specifications, repair or replace. Then confirm that the malfunction symptom is eliminated.
CAUTION: To prevent damage to the scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.
STEP 5. Using scan tool MB991502, check data list item 11: Heated Oxygen Sensor (front).
- Voltage should fluctuate between 0 - 0.4 volts and 0.6 - 1.0 volts while idling after the engine has been warmed.
If the voltage does not fluctuate, go to Step 6. If the voltage fluctuates, go to Step 8.
STEP 6. Check the fuel pressure.
If correct, go to Step 7.
If incorrect, repair or replace. Then confirm that the malfunction symptom is eliminated.
STEP 7. Check the following items.
1. Check the following items, and repair or replace the detective 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.
STEP 8. Check the fuel pressure.
If correct, go to Step 9.
If incorrect, repair or replace. Then confirm that the malfunction symptom is eliminated.
STEP 9. Check the following items.
1. Check the following items, and repair or replace the defective items.
a. Check the ignition coils, spark plugs, spark plug cables.
b. Check compression.
c. Check the fuel filter or fuel line for clogging.
d. Broken air intake hose.
e. Clogged air cleaner.
f. Clogged exhaust system.
Then confirm that the malfunction symptom is eliminated.