My 2007 b2300 manual has a code p0171. LTFT stays a 25% all the time from idle to 75 mph.


I have changed Fuel filter, MAF, Both oxygen sensors. No Vacuum leaks. New air filter. Cleaned injectors, Cleaned air inlet.


Help?

 

Welcome to the forum

Lean(or rich) codes do not mean engine is actually running Lean(or rich), for lean it means computer is having to add more fuel than it calculated, when fuel trims exceed +20 it will set a lean code

Just to be sure about no Vacuum/air leaks do this test
Warm up engine and let it idle
Unplug 2 wire connector on IAC Valve
Idle should drop to 500rpms or so, barely running, or it will stall, either is GOOD, it means no air leaks

If idle stays as it was, no drop, then replace PCV valve(based on MAF and O2 working)
The PCV Valve on the 2.3l should be changed every 2 years, Ford says every year, lol
PCV Valve is a metered "vacuum leak", if it sticks open it can cause lean codes, there is no PCV sensor
Its a pain to access, drivers side of engine, in the center down low, most access it through front wheel well on that side

Next step will be to test Fuel Pressure
Rangers had no fuel pressure sensor, so computer bases it's calculations on the "assumption" of 55 to 65PSI pressure(60psi)
If pressure is 40psi or less then you get Lean codes
The fuel pump assembly in the gas tank sets the fuel pressure, the fuel pump and the Fuel Pressure Regulator are both on that assembly

Partially Blocked exhaust, this would effect higher speed driving which you don't mention, so unlikely, but can cause lean codes

Also check out this thread and the Video in it: https://www.therangerstation.com/for...o-this.195033/

2009 but same 2.3l engine

 

Thx I already changed my evap valve because of evap code.

I will post my results.

 

FYI remember the LTFT stays at 25% all the time. Could bad PCV cause this?

 

Yes, if its stuck open

Lean or fuel trims above +20

Means there is unreported air coming into the intake manifold without passing thru the MAF sensor
OR
There is less fuel coming in than computer expects

You can also look at "intake air temp" that tells computer the air temp so it can compensate for cold and warmer air, if its reporting -20degF and its 70degF outside that will cause errors in the calculations

 

The engine was idling and disconnected IAC Engine Died immediately. So no air leak. Need to check Fuel Pressure. Couldn't change PCV will do next week.

 

Intake air temp shows 109 degree. it's texas and hot.

 

I still have the P0171 code. After 3 years. I tried disconnecting IAC and engine stop immediately. Changed both OS2, MAF, Fuel Filter, Evap sensors,

The LTFT stays HIGH (25) all the time. Idle to 75 MPH.

FYI getting 25MPG HWY?

HOW do I fix the P0171 code? HELP?