California
Injector Circuit:
Connectors: A-21X, B-01, B-02, B-05, B-06, B-25, B-26, B-48, C-51 <M/T>, C-52 <A/T>:
Fuel Trim Circuit
CIRCUIT OPERATION
- The injector power is supplied from the MFI relay (terminal 1).
- The ECM
TECHNICAL DESCRIPTION
- If a malfunction occurs in the fuel system, the fuel trim value becomes too large or too small.
- The ECM
DTC SET CONDITIONS
Check Conditions
- Under the closed loop air/fuel ratio control.
- Intake air temperature is higher than -10°C (14°F).
- Barometric pressure is higher than 76 kPa (11 psi).
- Volume air flow sensor output frequency is 100 Hz or more.
Judgment Criteria
- Long-term fuel trim has continued to be higher than +12.5 percent or lower than -12.5 percent for 5 seconds.
- Short-term fuel trim has continued to be higher than +7.4 percent or lower than -7.4 percent for 5 seconds.
Check Conditions
- During closed loop air/fuel ratio control.
- Intake air temperature is higher than -10°C (14°F).
- Barometric pressure is higher than 76 kPa (11 psi).
- Volume air flow sensor output frequency is 75 Hz or less.
Judgment Criteria
- Long-term fuel trim has continued to be higher than +12.5 percent or lower than -12.5 percent for 5 seconds.
- Short-term fuel trim has continued to be higher than +12.4 percent or lower than -12.4 percent for 5 seconds.
Check Conditions
- During closed loop air/fuel ratio control.
- Intake air temperature is higher than -10°C (14°F).
- Barometric pressure is higher than 76 kPa (11 psi).
- Volume air flow sensor output frequency is 75 Hz or more.
Judgment Criteria
- Long-term fuel trim has continued to be higher than +12.5 percent or lower than -12.5 percent for 5 seconds.
- Short-term fuel trim has continued to be higher than +17.4 percent or lower than -7.4 percent for 5 seconds.
Check Conditions
- During closed loop air/fuel ratio control.
- Intake air temperature is higher than -10°C (14°F).
- Barometric pressure is higher than 76 kPa (11 psi).
- Volume air flow sensor output frequency is 75 Hz or less.
Judgment Criteria
- Long-term fuel trim has continued to be higher than +12.5 percent or lower than -12.5 percent for 5 seconds.
- Short-term fuel trim has continued to be higher than +22.4 percent or lower than -12.4 percent for 5 seconds.
Check Conditions
- During closed loop air/fuel ratio control.
- The heated oxygen sensor (front) is active.
Judgment Criteria
- Long-term fuel trim has continued to be higher than +12.5 percent or lower than -12.5 percent for 5 seconds.
- Short-term fuel trim has continued to be higher than +25.0 percent or lower than -30.0 percent for 5 seconds.
TROUBLESHOOTING HINTS
The most likely causes for this code to be set are:
- Volume air flow sensor failed.
- Injector (Number 1, 3, 5) failed.
- Incorrect fuel pressure.
- Air drawn in from gaps in gasket, seals, etc.
- Right bank heated oxygen sensor failed.
- Engine coolant temperature sensor failed.
- Intake air temperature sensor failed.
- Barometric pressure sensor failed.
- Exhaust leak.
- Use of incorrect or contaminated fuel.
- ECM failed.
- PCM failed.
DIAGNOSIS
Required Special Tool:
MB991502: Scan Tool (MUT-II)
STEP 1. Check the exhaust leaks.
If not malfunctioning, go to Step 2.
If malfunctioning, repair or replace it.
Then go to Step 16.
STEP 2. Check the intake system vacuum leak.
If not malfunctioning, go to Step 3.
If malfunctioning, repair or replace it. Then go to Step 16.
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
STEP 3. Using scan tool MB991502, check data list item 12: Volume Air Flow Sensor.
1. Connect scan tool MB991502 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB991502 to the data reading mode for item 12, Volume Air Flow Sensor.
- When idling, between 17 and 46 Hz (between 2.2 and 5.7 g/s).
- When 2,500 r/min, between 63 and 103 Hz (between 9.0 and 14.7 g/s).
If within specifications, go to Step 4.
If not within specifications, refer to DTC P0100 - Volume Air Flow Circuit Malfunction.
STEP 4. Using scan tool MB991502, check data list item 13: Intake Air Temperature Sensor.
1. Turn the ignition switch to "ON" position.
2. Set scan tool MB991502 to the data reading mode for item 13, Intake Air Temperature Sensor.
- The intake air temperature and temperature displayed on the scan tool should be within 10%.
If they match, go to Step 5.
If they do not match, refer to DTC P0110 - Intake Air Temperature Circuit Malfunction.
STEP 5. Using scan tool MB991502, check data list item 21: Engine Coolant Temperature Sensor.
1. Turn the ignition switch to "ON" position.
2. Set scan tool MB991502 to the data reading mode for item 21, Engine Coolant Temperature Sensor.
- The engine coolant temperature and temperature displayed on the scan tool should be within 10%.
If they match, go to Step 6.
If they do not match, refer to DTC P0115 - Engine Coolant Temperature Circuit Malfunction.
STEP 6. Using scan tool MB991502, check data list item 25: Barometric Pressure Sensor.
1. Turn the ignition switch to "ON" position.
2. Set scan tool MB991502 to the data reading mode for item 25, Barometric Pressure Sensor.
- At an altitude 0 m (0 ft.), 101 kPa.
- At an altitude 600 m (1 ,969 ft.), 95 kPa.
- At an altitude 1,200 m (3,937 ft.), 88 kPa.
- At an altitude 1,800 m (5,906 ft.), 81 kPa.
If within specifications, go to Step 7.
If not within specifications, refer to DTC P0105 - Barometric Pressure Circuit Malfunction.
STEP 7. Check injector intermediate connector B-48 at the right bank injector.
1. Disconnect the injector intermediate harness connector.
2. Measure the resistance between injector side connector terminals 1 and 2 (No.1 injector), 1 and 3 (No.3 injector), 1 and 4 (No.5 injector).
Standard value: 13 - 16 ohms [at 20°C (68°F)]
If within specifications, go to Step 10.
If not within specifications, go to Step 8.
STEP 8. Check the right bank injector.
1. Remove the intake manifold.
2. Disconnect the injector connector deviated from the standard value at Step 7.
3. Measure the resistance between injector side connector terminals 1 and 2.
Standard value: 13 - 16 ohms [at 20°C (68°F)]
If within specifications, go to Step 9.
If not within specifications, replace the injector. Then go to Step 16.
STEP 9. Check harness connector B-01 or B-05 or B-26 at the right bank injector for damage.
1. Check the injector connector deviated from the standard value at Step 7.
If the harness connector is in good condition, repair the harness wire between the injector connector and injector intermediate harness connector. Then go to Step 16.
If the harness connector is damaged, repair or replace it.
Refer to Harness Connector Inspection. Then go to Step 16.
STEP 10. Check intermediate injector harness harness connector B-48 for damage.
If harness connector B-48 is in good condition, go to Step 11.
If harness connector B-48 is damaged, repair or replace it.
Refer to Harness Connector Inspection. Then go to Step 16.
STEP 11. Check the harness connector C-51 at the ECM
If harness connector C-51
If harness connector C-51
Refer to Harness Connector Inspection. Then go to Step 16.
STEP 12. Check the harness wire between injector connectors B-01, B-05, B-26 and ECM connector C-51
If the wires between injector connectors B-01, B-05, B-26 and ECM connector C-51
If the wires between injector connectors B-01, B-05, B-26 and ECM connector C-51
STEP 13. Check the fuel pressure.
Refer to Fuel Pressure Test.
If correct, go to Step 14.
If incorrect, repair or replace it. Then go to Step 16.
STEP 14. Check for entry of foreign matter (water, kerosene, etc) into fuel.
If OK, go to Step 15.
If fuel is contaminated, replace the fuel. Then go to Step 16.
STEP 15. Replace the right bank injectors.
1. Replace the right bank injectors.
2. Carry out a test drive with the drive cycle pattern. Refer to Procedure 2 - Fuel Trim Monitor.
3. Check for the diagnostic trouble code (DTC).
If DTC P0170 is not output, the inspection is complete.
If DTC P0170 is not output, replace the ECM or PCM. Then go to Step 16.
STEP 16. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Procedure 2 - Fuel Trim Monitor.
2. Read the diagnostic trouble code, and confirm that diagnostic trouble code P0170 does not reset.