DTC P1171 Fuel System Lean During Acceleration. GMC Truck Sonoma Pickup

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1998 🢒 Sonoma Pickup - 2WD 🢒 DTC 🢒 DTC P1171 Fuel System Lean During Acceleration


(1)	Fuel Pressure Regulator
(2)	Fuel Shut Off Adapter J 37287
(3)	Fuel Return Line
(4)	Quick Connect Adapter
(5)	Fuel Pressure Pinch Point
(6)	Fuel Pressure Pinch Point
(7)	Fuel Pressure Gauge Kit J 29658-D
(8)	Fuel Filter
(9)	Fuel Pressure Line

System Description

The PCM's internal circuitry can identify if the vehicle fuel system is capable of supplying adequate amounts of fuel during heavy acceleration (power enrichment). When a power enrichment mode of operation is requested during a Closed Loop operation (by heavy acceleration), the PCM provides additional fuel to the engine. Under these conditions the PCM should detect a rich condition. Whenever this rich exhaust is not detected, a DTC P1171 sets. A plugged fuel filter or restricted fuel line can prevent adequate amounts of fuel from being supplied during power enrichment mode.

Conditions For Setting The DTC

•	The engine has been running for longer than 20 seconds.

•	The Engine Coolant Temperature (ECT) is greater than 20°C (68°F).

•	The O2S 1 operating in a Closed Loop.

•	The fuel Injector BPW is greater than 0.

•	The fuel delivery system is in the power enrichment mode.

•	One or more of the following DTCs are not set; P0131, P0132, P0133, P0134, P1133.

•	The O2S 1 voltage is less than 300 mV for 5 seconds.

Action Taken When the DTC Sets

•	The PCM records the operating conditions at the time the diagnostic fails. The Failure Records buffers stores this information.

•	A history DTC is stored.

Conditions for Clearing the DTC

•	A History DTC clears after 40 consecutive warm up cycles without a fault.

•	Use a scan tool to clear the DTCs.

Diagnostic Aids

•	A restricted fuel filter can supply adequate amounts of fuel at idle, but may not be able to supply enough fuel during heavy acceleration. Water or alcohol in the fuel may cause low O2S 1 voltage during acceleration.

•	Check for faulty or plugged fuel injectors.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.

This step checks to see if the O2S 1 is operating properly.

If no malfunctions have been found at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.

DTC P1171-Fuel System Lean During Acceleration

Step	Action	Value(s)	Yes	No
1	Was the Powertrain On-Board Diagnostic (OBD) System Check performed?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Are any component related DTCs set?	--	Go to Component DTC table	Go to Step 3
3	Check the vehicle for an adequate amount of fuel. Add fuel to the vehicles fuel tank, if the tank is almost empty. Was it necessary to add fuel?	--	Go to Step 5	Go to Step 4
4	Using the scan tool, observe the O2S 1 voltage while running the engine at the specified temperature and RPM. O2S 1 voltage should vary from the specified voltage and occasionally toggle above the specified voltage. Does the O2S 1 toggle?	75°C - 95°C (167°F - 203°F) 1200 RPM 100 - 900 mV 447 mV	Go to Fuel System Diagnosis	Go to DTC P0134 O2S Circuit Insufficient Activity Sensor 1
5	Using the scan tool, clear the DTCs. Start the engine and idle at normal operating temperature. Operate the vehicle within the conditions for setting this DTC as specified in the supporting text. Does the scan tool indicate that this diagnostic has ran and passed?	--	Go to Step 6	Go to Step 2
6	Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed?	--	Go to the Applicable DTC table	System OK Go to Diagnostic Aids