F150 Ecoboost Forum banner

1 - 3 of 3 Posts

·
Registered
Joined
·
1,550 Posts
Discussion Starter #1
My truck runs great. Fuel consumption seems to be high in city driving. I average about 13-14 MPG city. I have been watching several PIDS for a while now and I notice that my LTFT are -8 on bank 1 and -3 on bank 2 during idle. Give it some gas and they quickly correct to 0. If I am decelerating and I take my foot off the gas, same thing, they immediately drop to the negative. My understanding is the truck is running rich at idle, so the PCM is taking fuel away. Best I can surmise is I have a leaking fuel injector, or a combination of leaking injectors. To the best of my knowledge the injectors are original, 80K on the clock, Canadian imported truck. I have fixed the timing chain, replaced all O2 sensors, and installed CRP manifolds. Those are the only engine mods. So before I drop the $450 on injectors and dive into the truck I was hoping an expert could tell me if there is some definitive way of diagnosing this as a leaking fuel injector? or something else? What PIDs should I watch to diagnose this?

Again, no codes, truck idles and runs fine. No stumbling. No hesitation. Just the typical piss poor MPG in city driving (Highway mileage is ~18-20) and LTFT in the negative only at idle.
 

·
Registered
Joined
·
11 Posts
Bump for some more LTFT data.
My truck is idling slightly rough intermittently.
Idle LTFT is -14bank1 -17bank2.
Running down the highway is -8 b1 -13b2
Accelerating Varies LTFT with throttle max is around 2-3 positive.
282kmi
Fuel is 91 octane, ethanol free.
16-17 city 18-19 highway with 12ply mud grips and grill guard.
 

·
Registered
Joined
·
83 Posts
Honestly the long term fuel trims seam to be okay, they will never run at 0. The usually get to a place once the short term fluctuates. Some scanners drop the LTFT and they go to 0 off idle. Check engine won’t set till 15 or 20 depending on make, never watched on a Ford. Anything under 10 is usually good. You could have a dirty or carbon buildup on the bottom of the injector, allowing it to saturate at the lower idle fuel pressures. I wouldn’t spend $450 for this, it might get worse or it could run like this forever. If you want to just try something. Try cleaning the throttle body and MAF sensors. Seeing how they change.
 
1 - 3 of 3 Posts
Top