Inspection Procedure 12
COMMENT- In cases such as the above, the ignition system, air/fuel mixture, idle air control motor or compression pressure may be faulty. In addition, if the engine suddenly stalls, the cause may also be a loose connector.
TROUBLESHOOTING HINTS
The most likely causes for this case:
- Malfunction of the ignition system.
- Malfunction of air/fuel ratio control system.
- Malfunction of the IAC system.
- Vacuum leak.
- Improper connector contact.
DIAGNOSIS
Required Special Tool:
MB991502: Scan Tool (MUT-II)
STEP 1. Check if the battery terminal is disconnected
Has the battery terminal been disconnected lately?
If no, go to Step 2.
If yes, start the engine and let it run at idle for approximate 10 minutes after engine warm-up. Then, if a malfunction occurs, go to Step 2.
CAUTION: To prevent damage to the scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.
STEP 2. Using scan tool MB991502, read the diagnostic trouble code (DTC).
If DTC is not output, go to Step 3.
If DTC is output, go to Trouble Code Diagnostic Procedures.
STEP 3. Check the idle air control (IAC) motor operation sound.
1. Check that the engine coolant temperature is 20° C (68° F) or below.
NOTE: Disconnecting the engine coolant temperature sensor connector and connecting the harness side of the connector to another engine coolant temperature sensor that is at 20° C (68° F) or below is also okay.
2. Check that the operation sound of the IAC motor can be heard after the ignition is switched "ON" (but without starting the engine).
- An operation sound should be heard. If a sound is heard, go to Step 4.
If no sound is heard, refer to DTC P0505 - Idle Control System Malfunction.
STEP 4. 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 5.
If no sound is heard, refer to DTC P0201, P0202, P0203, P0204 - Injector Circuit Malfunction.
STEP 5. Checking by operating the accelerator pedal
1. Does the engine stall right after the accelerator pedal is released?
If no, go to Step 6.
If yes, carry out the following cleaning or adjustment.
- Clean the throttle valve area. Then confirm that the malfunction symptom is eliminated.
STEP 6. Engine stall reproduction test.
If the engine stall is reproduced easily, go to Step 7. If the engine stall is not reproduced, check if the following signals change suddenly by wiggling the circuit harness and connectors.
- Crankshaft position sensor signal.
- Volume air flow sensor signal.
- Injector drive signal.
- Primary and secondary ignition signal.
- Fuel pump drive signal.
- ECM power supply voltage.
- PCM power supply voltage.
If the engine stall is produced, inspect that circuit harness and connector. 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 7. Using scan tool MB991502, check data list and actuator test.
1. Check the following items in the data list.
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 59: Heated Oxygen Sensor (rear).
e. Item 11: Heated Oxygen Sensor (front).
f. Item 27: Power Steering Pressure Switch.
g. Item 28: A/C Switch.
2. Check the following items in the actuator test.
Actuator Test Reference Table
a. Item 10: EGR Solenoid.
If the checks above meet the specifications, go to Step 8. 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 8. Using scan tool MB991502, check data list item 11: Heated Oxygen Sensor (front).
- Fluctuates between 0 - 0.4 volts and 0.6 - 1.0 volts while idling after the engine has been warmed.
If incorrect, go to Step 9.
If correct, go to Step 12.
STEP 9. Check the fuel pressure.
If correct, go to Step 10.
If incorrect, 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 10. Using scan tool MB991502, check data list.
1. Check the following items in the data list.
Data List Reference Table & Normal Scan Data Values
a. Item 45: Idle Air Control Motor Position.
If the checks above meet the specifications, go to Step 11. If the checks above do not meet the specifications, adjust the basic idle speed. Refer to Basic Idle Speed Adjustment. Adjustments Then confirm that the malfunction symptom is eliminated.
STEP 11. Check the following items.
1. 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.
- Injector clogged.
Then confirm that the malfunction symptom is eliminated.
STEP 12. Check the ignition timing.
Refer to On-vehicle Service.
If within specifications, go to Step 13.
If the standard value is deviated from, 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.
STEP 13. 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 if the injectors are clogged.
c. Check compression.
d. Check if the foreign materials (water, kerosene, etc.) got into fuel.
Then confirm that the malfunction symptom is eliminated.