The SES light came on on my 03 F150 5.4L today for both banks lean P0171 and p0174 I believe. I plugged in the superchips from the bosses 7.3 to pull the codes and to look at the fuel trims. here are the trims; it starts out at idle and then after a few seconds I put some throttle in it for a bit, and then let it idle back down. What do you guys think I need to look at first?

 

Without even bothering to look at the video...

You should look for the vacuum leak since that's what usually causes your set of symptoms. Start with the PCV valve plumbing paying special attention to all the rubber elbows.

 

Ordered the new PCV hose assembly. On the old one, the little short section right after the tee in the hose basically came apart in my hand when I went to remove it. Now my fuel trims are back down where they should be.

 

welp, that didn't last long... Started out with a lean code on Bank 1 but fuel trims were both way off. Now the second lean code has come back. Where is the next usual suspect to check? My heads hurting from searching the web on this.

 

Have you checked for other vac leaks ? How is your MAF sensor preforming ?

 

I cleaned the maf awhile back. fuel trims back way down to practically zero when on the throttle, its only sky high when it idle. Its been too cold out to really dig around under the hood, nothing has really stood out at me yet.... maybe tomorrows project.

 

I just went through this fiasco trying to find the cause of high LTFT's......check it with a propane torch and a length of hose. Check all around the edge of the intake manifold gasket area's where the injectors are. If the short term trims level out then that is your leaks. My leak was so small that it was bearly detectable. Changed the manifold gaskets and all is well. It is a pretty easy job. And use Felpro Perma-seal gaskets. They are thicker and seal better around any imperfections. Good luck.