i recently had my 2006 f150 5.4 in for a new injector. The dealer replaced that and also said they wanted to do a code upgrade. Not sure what this is, however, now i am getting 12 mpg at 63 mph on the highway and about 9 mpg in the city. i used to get at least 13.7 and 17.8.

What could have happened?

 

Maybe they drained out half of your tank of gas..

You'll have to call them.

Steve

 

could be your running les officiant while the engine pcm relearns. could also be winter fuel and conditions. give it another tank of gas..

 

I have a friend that has an "04 F250 that he bought from a man that did all his own service (wasn't much because truck had less than 20k on it). He bought it last month and went to put a super chip on it. He got an error code, so he called the guy from superchip. He said the guy begged him to never take the truck to a dealership ever. The superchip guy said, that dealerships are under federal regualtions to re-set computer codes to meet current cafe' standards, (emmission controls whateve else ???). When they do this it obviously effects your MPG. Well because the man did his own service work, my friend still has 700 ftlbs of torque and much better MPG than say a truck that has had its code re-set. I would talk to the dealer to see if it is something like that in your case. Good luck!

 

Where's the BS flag?

 

That's what the guy from super chip told him after he installed the software upgrade. The truck is scary fast and quick. You will need to grab the oh-crap handle when you ride.

 

ohhhhhh.........you said a "F250" - I might believe that with a tweaked diesel.

 

Sorry about that. It is a diesel.

 

Another reason not to go the the dealershiip for service!

 

ditto