System Description
The powertrain control module (PCM) can identify if the vehicle fuel system is capable of supplying adequate amounts of fuel during heavy acceleration. This condition is called a power enrichment mode of operation. If power enrichment is requested during a Closed Loop operation, the PCM will provide more fuel to the engine. Under these conditions, the PCM should detect a rich condition. If the PCM does not detect a rich exhaust at this time, DTC P1171 will set. A plugged fuel filter, or a restricted fuel line can prevent adequate amounts of fuel from being supplied during the power enrichment mode.
Conditions for Running the DTC
| • | DTCs P0131, P0132, P0133, P0134, or P1133 are not set. |
| • | The engine coolant temperature (ECT) is more than 20°C (70°F). |
| • | The engine has been running for longer than 20 seconds. |
| • | The engine is operating in a Closed Loop operation. |
Conditions for Setting the DTC
| • | The O2S 1 voltage is less than 300 mV for 5 seconds. |
| • | The engine is in the power enrichment mode. |
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Diagnostic Aids
| • | A restricted fuel filter can supply adequate amounts of fuel at idle, but may not be able to supply enough fuel during a heavy acceleration. |
| • | Water or alcohol in the fuel may cause a low O2S 1 voltage during acceleration. |
| • | Check for an adequate amount of fuel in the fuel tank. |
| • | When the engine is idling or at steady cruise, the O2S 1 voltage should vary from between approximately 100 mV to 900 mV. During the power enrichment mode, more fuel is needed and O2S 1 voltage should rise above 447 mV. |
| • | Check for malfunctioning or plugged injectors. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 |
Are any component related DTCs set? | -- | Go to Step 3 | |
3 |
Did you need to add fuel? | -- | Go to Step 5 | Go to Step 4 |
Does the O2S 1 toggle? | 75-95°C (167-203°F) 1,200 RPM 100-900 mV 447 mV | Go to Fuel System Diagnosis | Go to DTC P0134 | |
5 |
Does the DTC run and pass? | -- | Go to Step 6 | Go to Step 2 |
6 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
