Keep causing a skip or lugging code P0171

Have you tried just listening to the injectors? Listen for a clicking sound coming from the injectors while the engine is running by using a mechanic's stethoscope, or a long screwdriver.

O ok then nevermind my last post then. Injector circuit is good then. Yeah im not sure if just one ground is really enough there.

Ok I really thought it was with the injectors but we are going to have to go further down the fuel circuitry than that. Next we will need to test the PCM. Do this by turning ignition OFF and connecting PCM to the breakout box. Connect non-powered 12-volt test light between each injector ( 1 at a time ) and test pins Number 71 and 97. Crank or start the engine. If the light glows dimly then the PCM is ok and we will go on further with diagnosis. If the test light does not glow dimly (no light/ bright light) then the PCM needs replaced.

Need to crank or start engine

Ok then this rules out your PCM AND your fuel injectors so it must be in the air induction. I may have already said this or you may have already done these but I can't remember so check the PCV system for leaks or restrictions, check all vacuum hoses for damage and tight connections.

1997 Ford F150 po171 code

A code P0171 or P0174 indicate the engine is running lean. This means there is too much air and/or not enough fuel. You can confirm the engine is running lean by looking at Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT). Normally, STFT and LTFT should be plus or minus 8 from zero. If STFT and/or LTFT are more than about +10 or higher, it indicates the engine is running LEAN. Negative numbers (-10 or more) indicates the engine is running RICH.

A lean fuel condition can be caused by:

* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (Use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (Try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)

* TIP: On many Fords, a P0171 and/or P0174 Lean Code may sometimes appear because of a bad Differential Pressure Sensor (DPFE). This sensor monitors EGR flow, and is located on the engine near the EGR valve. There are two hoses that connect the sensor to the tube that runs from the exhaust manifold to the EGR valve. The sensor misreads EGR flow and the computer increases EGR which has a leaning effect on the fuel mixture. The fix is to replace the DPFE sensor

Follow the link below to learn how to check an O2 sensor before replacing them..

https://www.2carpros.com/how_to/how_to_test_oxygen_sensor.htm

From: miamiii13
To: rasmataz
Posted: Mon Mar 16, 2009 10:30 pm
Subject: any other ideas
do u have any other suggestions to try or to eliminate things

Look for vacuum leaks and try the scantool for the trimmings this is as far as I can take you-Sorry

Sensing wire should be red/light green for your trucks O2 sensors