DESCRIPTION
The fuel trim is related to the feedback compensation value, not to the basic injection duration. The fuel trim consists of both the short-term and long-term fuel trims.
The short-term fuel trim is fuel compensation that is used to constantly maintain the air fuel ratio at stoichiometric levels. The signal from the air fuel ratio sensor indicates whether the air fuel ratio is rich or lean compared to the stoichiometric ratio. This triggers a reduction in the fuel injection volume if the air fuel ratio is rich and an increase in the fuel injection volume if lean.
Factors such as individual engine differences, wear over time and changes in operating environment cause short-term fuel trim to vary from the central value. The long-term fuel trim, which controls overall fuel compensation, compensates for long-term deviations in the fuel trim from the central value caused by the short-term fuel trim compensation.
If both the short-term and long-term fuel trims are lean or rich beyond predetermined values, it is interpreted as a malfunction, and the ECM illuminates the MIL and stores a DTC.
DTC No. |
DTC Detection Condition |
Trouble Area |
---|---|---|
P0171 |
With a warm engine and stable air fuel ratio feedback, the fuel trim is considerably in error to the lean side (2 trip detection logic). |
|
P0172 |
With a warm engine and stable air fuel ratio feedback, the fuel trim is considerably in error to the rich side (2 trip detection logic). |
|
HINT:
MONITOR DESCRIPTION
Under closed loop fuel control, fuel injection volumes that deviate from those estimated by the ECM cause changes in the long-term fuel trim compensation value. The long-term fuel trim is adjusted when there are persistent deviations in the short-term fuel trim values. Deviations from the fuel injection volumes estimated by the ECM also affect the average fuel trim learned value, which is a combination of the average short-term fuel trim (fuel feedback compensation value) and the average long-term fuel trim (learned value of the air fuel ratio). If the average fuel trim learned value exceeds the malfunction thresholds, the ECM interprets this as a fault in the fuel system and stores a DTC.
Example:
The average fuel trim learned value is +35% or more, or -35% or less, the ECM interprets this as a fuel system malfunction.
MONITOR STRATEGY
Related DTCs |
P0171: Fuel trim lean P0172: Fuel trim rich |
Required Sensors/Components (Main) |
Fuel system |
Required Sensors/Components (Related) |
Air fuel ratio sensor Mass air flow meter Crankshaft position sensor |
Frequency of Operation |
Continuous |
Duration |
Within 10 seconds |
MIL Operation |
2 driving cycles |
Sequence of Operation |
None |
TYPICAL ENABLING CONDITIONS
Fuel-trim:
Monitor runs whenever following DTCs not stored |
P0010 (Camshaft Timing Oil Control Valve) P0011 (VVT System - Advance) P0012 (VVT System - Retard) P0016 (VVT System - Misalignment) P0013 (Exhaust Camshaft Timing Oil Control Valve) P0014 (Exhaust VVT System - Advance) P0015 (Exhaust VVT System - Retard) P0017 (Exhaust VVT System - Misalignment) P0031, P0032, P101D (Air Fuel Ratio Sensor Heater) P0102, P0103 (Mass Air Flow Meter) P0115, P0117, P0118 (Engine Coolant Temperature Sensor) P0125 (Insufficient Coolant Temperature for Closed Loop Fuel Control) P0120, P0121, P0122, P0123, P0220, P0222, P0223, P2135 (Throttle Position Sensor) P0335 (Crankshaft Position Sensor) P0340, P0342, P0343 (Camshaft Position Sensor) P0365, P0367, P0368 (Exhaust Camshaft Position Sensor) P0351 - P0354 (Igniter) P0500 (Vehicle Speed Sensor) P219A, P219C, P219D, P219E, P219F (Air Fuel Ratio Imbalance) |
Fuel system status |
Closed loop |
Battery voltage |
11 V or higher |
Either of following conditions 1 or 2 met |
- |
1. Engine speed |
Less than 800 rpm |
2. Engine load |
16.25% or more |
Catalyst monitor |
Not executed |
TYPICAL MALFUNCTION THRESHOLDS
Fuel-trim:
Purge-cut |
Executing |
Either of following conditions 1 or 2 met |
- |
1. Average between short-term fuel trim and long-term fuel trim |
35% or more (varies with engine coolant temperature) |
2. Average between short-term fuel trim and long-term fuel trim |
-35% or less (varies with engine coolant temperature) |
CONFIRMATION DRIVING PATTERN
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
HINT:
If a pending DTC is output, the system is malfunctioning.
HINT:
WIRING DIAGRAM
Refer to DTC P0102 (See page ).
Refer to DTC P2195 (See page ).
CAUTION / NOTICE / HINT
NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.
HINT:
PROCEDURE
1. |
CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0171 OR P0172) |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Trouble Codes.
(e) Read the DTCs.
Result |
Proceed to |
---|---|
DTC P0171 or P0172 is output |
A |
DTC P0171 or P0172 and other DTCs are output |
B |
HINT:
If any DTCs other than P0171 or P0172 are output, troubleshoot those DTCs first.
B |
GO TO DTC CHART |
|
2. |
CHECK PCV HOSE CONNECTIONS |
(a) Check the PCV hose connections (See page ).
OK:
PCV hose is connected correctly and is not damaged.
NG |
REPAIR OR REPLACE PCV HOSE |
|
3. |
CHECK INTAKE SYSTEM |
(a) Check the intake system for vacuum leaks (See page ).
OK:
No leakage from intake system.
HINT:
NG |
REPAIR OR REPLACE INTAKE SYSTEM |
|
4. |
PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME) |
(a) Connect the Techstream to the DLC3.
(b) Start the engine.
(c) Turn the Techstream on.
(d) Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
(e) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume / AFS Voltage B1S1 and O2S B1S2.
(f) Perform the Control the Injection Volume operation with the engine idling.
(g) Monitor the voltage outputs of the air fuel ratio sensor and the heated oxygen sensor (AFS Voltage B1S1 and O2S B1S2) displayed on the Techstream.
HINT:
Standard:
Techstream Display (Sensor) |
Injection Volume |
Status |
Voltage |
---|---|---|---|
AFS Voltage B1S1 (Air fuel ratio) |
+12% |
Rich |
Below 3.1 V |
-12% |
Lean |
Higher than 3.4 V |
|
O2S B1S2 (Heated oxygen) |
+12% |
Rich |
Higher than 0.55 V |
-12% |
Lean |
Below 0.4 V |
Status AFS Voltage B1S1 |
Status O2S B1S2 |
Air Fuel Ratio Condition and Air Fuel Ratio Sensor Condition |
Suspected Trouble Area |
Proceed to |
---|---|---|---|---|
Lean |
Lean |
Actual air fuel ratio lean |
|
A |
Rich |
Rich |
Actual air fuel ratio rich |
|
|
Lean |
Lean/Rich |
Air fuel ratio sensor malfunction |
|
B |
Rich |
Lean/Rich |
Air fuel ratio sensor malfunction |
|
HINT:
Refer to "Data List / Active Test" [AFS Voltage B1S1, O2S B1S2] (See page ).
B |
GO TO STEP 11 |
|
5. |
READ VALUE USING TECHSTREAM (COOLANT TEMP) |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Data List / Coolant Temp.
(e) Read the Data List twice, when the engine is both cold and warmed up.
Standard value:
With cold engine: Same as ambient air temperature.
With warm engine:
Between 75 and 100°C (167°F and 212°F).
HINT:
Perform "Inspection After Repair" after replacing the engine coolant temperature sensor (See page ).
NG |
REPLACE ENGINE COOLANT TEMPERATURE SENSOR |
|
6. |
READ VALUE USING TECHSTREAM (MAF) |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Data List / MAF and Coolant Temp.
(e) Allow the engine to idle until Coolant Temp reaches 75°C (167°F) or higher.
(f) Read MAF with the engine speed at 3000 rpm.
Standard:
Between 8.5 and 12.5 gm/s (shift lever: N position, A/C: Off).
NG |
GO TO STEP 16 |
|
7. |
CHECK FUEL PRESSURE |
(a) Check the fuel pressure (See page ).
NG |
REPAIR OR REPLACE FUEL SYSTEM |
|
8. |
CHECK FOR EXHAUST GAS LEAK |
(a) Check for exhaust gas leaks.
OK:
No gas leaks.
HINT:
Perform "Inspection After Repair" after repairing or replacing the exhaust system (See page ).
NG |
REPAIR OR REPLACE EXHAUST SYSTEM |
|
9. |
CHECK FOR SPARK (SPARK TEST) |
(a) Perform a spark test (See page ).
HINT:
|
10. |
INSPECT FUEL INJECTOR ASSEMBLY (INJECTION AND VOLUME) |
(a) Check the injection and volume.
HINT:
OK |
GO TO STEP 15 |
NG |
REPLACE FUEL INJECTOR ASSEMBLY |
11. |
INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE) |
NG |
REPLACE AIR FUEL RATIO SENSOR |
|
12. |
CHECK TERMINAL VOLTAGE (POWER SOURCE OF AIR FUEL RATIO SENSOR) |
NG |
GO TO STEP 21 |
|
13. |
CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM) |
NG |
REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR FUEL RATIO SENSOR - ECM) |
|
14. |
REPLACE AIR FUEL RATIO SENSOR |
(a) Replace the air fuel ratio sensor (See page ).
HINT:
Perform "Inspection After Repair" after replacing the air fuel ratio sensor (See page ).
|
15. |
PERFORM CONFIRMATION DRIVING PATTERN |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON and turn the Techstream on.
(c) Clear the DTCs (See page ).
(d) Turn the ignition switch off and wait for at least 30 seconds.
(e) Turn the ignition switch to ON and turn the Techstream on.
(f) Start the engine and warm it up.
(g) Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.
(h) Enter the following menus: Powertrain / Engine / Trouble Codes.
(i) Read the DTCs.
Result |
Proceed to |
---|---|
DTC P0171 or P0172 is output |
A |
DTC is not output |
B |
B |
END |
|
16. |
CHECK HARNESS AND CONNECTOR |
(a) Check the connection and terminal contact pressure of connectors and wire harness between the mass air flow meter and ECM (See page ).
HINT:
Repair any problems.
|
17. |
CHECK WHETHER DTC OUTPUT RECURS (DTC P0171 OR P0172) |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON and turn the Techstream on.
(c) Clear the DTCs (See page ).
(d) Turn the ignition switch off and wait for at least 30 seconds.
(e) Turn the ignition switch to ON and turn the Techstream on.
(f) Start the engine and warm it up.
(g) Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.
(h) Enter the following menus: Powertrain / Engine / Trouble Codes.
(i) Read the DTCs.
Result |
Proceed to |
---|---|
DTC P0171 or P0172 is output |
A |
DTC is not output |
B |
B |
END |
|
18. |
CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM) |
NG |
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
19. |
REPLACE MASS AIR FLOW METER |
(a) Replace the mass air flow meter (See page ).
HINT:
|
20. |
CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON and turn the Techstream on.
(c) Clear the DTCs (See page ).
(d) Turn the ignition switch off and wait for at least 30 seconds.
(e) Turn the ignition switch to ON and turn the Techstream on.
(f) Start the engine and warm it up.
(g) Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.
(h) Enter the following menus: Powertrain / Engine / Trouble Codes.
(i) Read the DTCs.
Result |
Proceed to |
---|---|
DTC is not output |
A |
DTC P0171 or P0172 is output |
B |
A |
END |
B |
REPLACE ECM |
21. |
CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - EFI MAIN NO. 2 RELAY) |
NG |
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
22. |
INSPECT ENGINE ROOM JUNCTION BLOCK ASSEMBLY (EFI MAIN NO. 2 RELAY) |
(a) Inspect the engine room junction block assembly (See page ).
OK |
REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - EFI MAIN MO. 2 RELAY) |
NG |
REPLACE ENGINE ROOM JUNCTION BLOCK ASSEMBLY |
Installation
INSTALLATION
CAUTION / NOTICE / HINT
HINT:
Use the same procedure for the RH side and LH side.
The procedure listed below is for the LH side.
PROCEDURE
1. INSTALL DOOR SIDE AIRBAG SENSOR
(a) Check that the ignition switch is off.
(b) C ...
Calibration
CALIBRATION
1. DESCRIPTION
(a) Follow the chart below to perform calibration.
Parts to be Replaced
Necessary Operation
Brake actuator assembly (Skid control ECU)
Perform engine variant learning
2. ...
Insufficient Coolant Temperature for Closed Loop Fuel Control (P0125)
DESCRIPTION
Refer to DTC P0115 (See page ).
DTC No.
DTC Detection Condition
Trouble Area
P0125
The engine coolant temperature does not reach the closed loop enabling
temperature for 20 minutes ...