Inspection Procedure 12
INSPECTION PROCEDURE 12: When the Engine Is Hot, It Stalls at Idle (die out).COMMENT
- In cases such as the above, the ignition system, air/fuel mixture, electronic control throttle valve system or compression pressure may be faulty. In addition, if the engine suddenly stalls, the cause may also be a connector damage.
TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Malfunction of the ignition system.
- Malfunction of air/fuel ratio control system.
- Malfunction of the electronic control throttle valve system.
- Malfunction of the EGR valve.
- Vacuum leak.
- Improper connector contact.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
STEP 1. Check if the battery terminal is disconnected.
Q: Has the battery terminal been disconnected lately?
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.
NO: Go to Step 2.
STEP 2. 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 the 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 items 1, 2, 3, 4: Injector.
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 following items in the actuator test. Refer to Actuator Test Reference Table. Actuator Test Reference Table
a. Item 1, 2, 3, 4: Injector.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are they operating properly?
YES: Go to Step 4.
NO: Refer to DTC P0201 - Injector Circuit-cylinder 1, DTC P0202 - Injector Circuit-cylinder 2, DTC P0203 - Injector Circuit-cylinder 3, DTC P0204 - Injector Circuit-cylinder 4.
STEP 4. Checking by depressing and releasing the accelerator pedal.
Q: Does the engine stall right after the accelerator pedal is released?
YES: Refer to On-vehicle Service - Throttle Body (Throttle Valve Area) Cleaning. Cleaning
NO: Go to Step 5.
STEP 5. Engine stall reproduction test.
Q: Is it easy to reproduce the engine stall?
YES: Go to Step 6.
NO: Check if the following signals change suddenly by wiggling the circuit harness and connectors.
a. Crankshaft position sensor signal.
b. Mass airflow sensor signal.
c. Injector drive signal.
d. Primary and secondary ignition signal.
e. Fuel pump drive signal.
f. ECM
Repair or replace it. Then confirm that the malfunction symptom is eliminated.
STEP 6. 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 5: Intake Air Temperature Sensor.
b. Item 6: Engine Coolant Temperature Sensor.
c. Item 83: Power Steering Pressure Switch.
d. Item 31: EGR valve (stepper motor).
e. Item 13: Throttle position sensor (main).
4. 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. Measure the sensor output voltage at ECM
1. Disconnect all ECM
2. Start the engine and run at idle.
3. Measure the voltage between terminal No. 92 and ground.
- Warm up the engine. When the engine is 2,500 r/min, the output voltage should repeat 0.5 to 1.4 volts alternately.
4. Measure the voltage between terminal No. 91 and ground.
- Warm up the engine. When the engine is 2,500 r/min, the output voltage should repeat 0.5 to 1.4 volts alternately.
5. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage within the specified range?
YES: Go to Step 9.
NO: Go to Step 8.
STEP 8. Check the fuel pressure.
Refer to On-vehicle Service - Fuel Pressure Test.
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 9. Check the ignition timing.
Refer to On-vehicle Service - Ignition Timing Check.
Q: Is the ignition timing normal?
YES: Check the following items, and repair or replace the defective items.
a. Check the ignition coil and spark plugs.
b. Check if the injectors are clogged.
c. Check compression pressure.
d. Check if the foreign materials (water, kerosene, etc.) got into fuel.
e. Check the EGR valve.
Then confirm that the malfunction symptom is eliminated.
NO: Check that the crankshaft position sensor and timing cover are in the correct position. Then confirm that the malfunction symptom is eliminated.