Hello everyone i have a 1999 F-150 with the 5.4l. Recently after the truck sat for one month, i started it up and noticed a bog around 40 mph when the transmission shifts into 3rd or overdrive. The engine through a code which was P0171 which is a lean code for bank 1. I checked the fuel injectors and they all had a rythmic tic. I also cleaned the MAF and changed the air filter. I wanted to check with you guys before i went any further. The truck also has an ATI procharger running 9psi with intercooler. The truck has 42 lb injectors lightning MAF, and a walbro 255 fuel pump. The truck was dynotuned by B&D racing here in los angeles. Any help would be much appriciated, thanks.

 

Whats the status on your pre-cat o2 sensors?

 

Check for vacuum leaks.

 

as far as i know the pre cat O2 sensors have not been changed in at least 4 years. I have checked for vaccum leaks and could not find any.

 

does anyone know how to easily remove the pre cat 02 sensors, they are really stuffed in there.

 

Is there any way you can use a scanner on your truck? So you can watch fuel trims and injector pulsewidth?

 

Well first off i changed the oxygen sensor on the passenger side today since thats the one that controls bank 1, and the problem is still there. The old oxygen sensor was black but did not look bad for being over 4 years old. The code P0171 is still coming up. As far as using a scanner to review fuel trims and injector pulsewidths i dont have access to that sort of equipment. The truck is getting re-tuned in two weeks and i just am trying to fix this problem my self before it goes in ( Gotta cut costs where i can) thanks for the help so far guys if anybodys has any more insight about my issue that would be great.