I have had my mustang on the diablo tune for about two years now, and a few months ago it threw two codes saying both bank 1 and 2 were running too lean. (I always use premium fuel)

I would clear the codes and the problem would go away for about a month, then it would throw the codes again, clear them, and it was gone again.....

then today it happened again! This time it is only code P0171 (Bank 1 running too lean)

I dont want to do any damage to my baby? What should I do? My fuel filter was changed about a year ago, and my fuel pump is only 3-4 years old, so that shouldnt be a problem....

should i just clear them again?

 

Are you pinging at all? I know it's not the best judge, but if you're really worried I'm sure you can push more fuel in at WOT and pull timing using the tuner.

 

No, no pinging what so ever, but its an automatic, and I am experiencing hesitation then a huge boost in acceleration....

However I think that has always been the case, at least it seems so to me

 

Vacum leak or a dirty maf. I doubt it has anything to do with fuel that code never does. It basicly means that the reading from the maf and the reading from the o2 sensors are not matching. I would put my money on a vacum leak.

 

well i dont think i have a vac. leak....i dont hear any hissing...even though the engine is loud...

I will try to clean my maf with some electronics cleaner that i have at home, but i wont be home for about a week....

every little thing that goes wrong with my car just really bothers me

 

so what does everyone think about my potential vaccum leak?

i replaced all my intake myself, and i dont think anythign is loose