when i got my truck in 07 i immediately did intake, catback and troyer tunes. all was fine for about a year or so. CEL comes on (p0171 left bank lean) so I clean the maf and cleared the code. didnt help, 3 days later the cel was back. clean maf again and clear the codes, 3 days go by and the code is back. the truck had 25k miles on it so i change the fuel filter and cleared the code. 3weeks go by and the code comes back. called troyer, they said probably the o2s. i cant afford new o2s so i switch the o2s from left to right and visa versa figuring if it is an o2, the code will change to p0172 (right bank lean) but it didnt, came back up with the same code so i know its not the o2s. i return the truck to stock tune and drive for 3 months with no code. put the tune back in and 3 weeks later the code is back. i found that if i put fuel system cleaner in it i can get about 4 months without the code coming up. this last time, i only got 2 months with that trick. im sick of the code, what could it be. i cant take it to ford cause the code wont come up with the stock tune in and troyer says its not their tunes because it ran for over a year without issues after i got the tune (im sure their right).

i checked for vac leaks, found none but put zip ties on all the vac lines that felt a little loose

any ideas?

 

Could be a gummed up Injector.. Before actually pulling the injectors, you could try running Seafoam through to see if it'll clean something out.

 

i agree, seafoam can work wonders.

 

whats the best way to use iton our trucks? i was told 1/3 of the bottle through a vac line, 1/3 of the bottle in the gas tank and 1/3 of the bottle in the engine oil

 

I haven't done it to my truck, but I've heard of people putting a full bottle through the gas tank. Check the instructions on the bottle, and research it a little for our trucks