05 Expedition MPG

My 05 Expedition used to get 14 - 14.5 MPG (roughly 420 - 435 Miles to the tank) I recently had to replace the engine due to bad injectors and now I get 10.7 MPG (290 to 314 to tank now). Does anyone know why this might be lowered? Info - I bought a 2007 engine and my mechanic tweeked maybe 3 or 4 parts (meaning took them off my old engine and put on the new, such as the manifold) to make it work. The 2007 injectors did not work, (waiting on the place I bought the engine to send my 05 injectors) so my check engine light stays on (assuming because of the injectors). However, the truck runs good and idles great, but horrible gas mileage! Please help!

My guess would be the mixing of the parts. Why would you buy a new engine, and then put old parts on it. Think about the reason why you changed the engine (bad injectors), and now you are going to put those same original bad injectors back on? When your mechanic does that, and if they work fine, I would suggest that you never go back to him.

My guess would be the mixing of the parts. Why would you buy a new engine, and then put old parts on it. Think about the reason why you changed the engine (bad injectors), and now you are going to put those same original bad injectors back on? When your mechanic does that, and if they work fine, I would suggest that you never go back to him.

:1: Agreed, are you putting on the bad injectors?

why the hell would you change the motor if you had a bad injector(s). most of the time you have to swap parts when you do an engine swap due to different wiring harness connections manifolds etc. that part I don't question but changing the motor in an expedition is a major bitch and not something you do for bad injectors.

We are all energy junkies....that's why gas is $3.30 a gallon. We import 70% of the oil we use from other countries and they have us by the you know what. Four miles per gallon isn't much difference on an Escort that gets 35-40 mpg. but it's a lot on an Expedition.

I don't think anyone suggested swapping the motor, its not worth it.