P1127

DESCRIPTION
The air/fuel control system, in addition to a number of sensors, includes the following components and systems:

- Intake air system.
- Exhaust system.

Evaporative emissions control system (includes purge control solenoid valve). Fuel injectors.
- Fuel pressure regulator.
- Fuel pump.

For the air/fuel ratio to be within limits, all of the sensors, components and systems associated with the air/fuel control system must function within normal parameters.

FAILURE CONDITIONS

FOR SHORT-TERM FUEL TRIM
The ECM will set a code and the Malfunction Indicator Lamp (MIL) will turn on if the short-term fuel trim value goes 10% to 15% rich [for P1123] or lean [for P1124] for 30 seconds during two driving cycles when the following conditions are met:

1. ECM is in closed loop operation.
2. Engine speed is below 1000 rpm.
3. Engine coolant temperature is above 158 °F (70 °C).
4. Canister purge system is not operating.
5. Mass air flow is less than or 6.6 g/s.

FOR LONG-TERM FUEL TRIM
The ECM will set a code and the Malfunction Indicator Lamp (MIL) will turn on if the long-term fuel trim value goes 10% to 15% rich [for P1127] or lean [for P1128] for 30 seconds during two driving cycles when the following conditions are met:

1. Engine load exceeds 2.0 milliseconds.
2. Engine speed is below 1000 rpm.
3. Engine coolant temperature is above 158 °F (70 °C).
4. Canister purge system is not operating.
5. Mass air flow is less than or 5.5 g/s.

Part 1 Of 2:

Part 2 Of 2:

TEST PROCEDURE