Inspection Procedure 18

INSPECTION PROCEDURE 18: Poor acceleration.

COMMENT
- Defective ignition system, abnormal air/fuel ratio, the electronic control throttle valve system, 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 electronic control throttle valve system.
- Malfunction of the fuel supply system.
- Poor compression pressure.
- Clogged exhaust system.

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.- III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A




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, check actuator test items 1, 2, 3, 4, 5, 6: Injector.

1. Turn the ignition switch to the "ON" position.
2. Check following items in the actuator test. Refer to Actuator Test Table.
a. Item 1, 2, 3, 4, 5, 6: Injector.

3. Turn they ignition switch to the "LOCK" (OFF) position.

Q: Are they operating properly?

YES: Go to Step 3.

NO: Refer to DTC P0201, P0202, P0203, DTC P0204, P0205, P0206 - Injector Circuit.

STEP 3. Check the ignition timing.

Refer to On-vehicle Service - Ignition Timing Check.

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. Datal List Reference Table
a. Item 5: Intake Air Temperature Sensor.
b. Item 6: Engine Coolant Temperature Sensor.
c. Item AC: Heated Oxygen Sensor Bank 1, Sensor 1 (right front)
d. Item AD: Heated Oxygen Sensor Bank 1, Sensor 2 (right rear)
e. Item AE: Heated Oxygen Sensor Bank 2, Sensor 1 (left front)
f. Item AF: Heated Oxygen Sensor Bank 2, Sensor 2 (left rear)
g. Item BB: Barometric Pressure Sensor

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 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. Datal List Reference Table
a. Item AC: Right Bank Heated Oxygen Sensor (front).
b. Item AE: Left Bank Heated Oxygen Sensor (front).
- Voltage should fluctuate between 0 - 0.4 volt and 0.6 - 1.0 volt while idling after the engine has been warmed.

3. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Are they operating properly?

YES: Go to Step 7.

NO: Go to Step 6.

STEP 6. 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 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. Check the ignition coil and spark plugs.
b. Check compression pressure.
c. Check the fuel filter or fuel line for clogging.
d. Check the EGR system.
e. Broken air intake hose.
f. Clogged air cleaner.
g. Clogged exhaust system.

Then confirm that the malfunction symptom is eliminated.

NO: Repair or replace it. Then confirm that the malfunction symptom is eliminated.