What can be causing the loss of mpg's??

 

I am averaging around 15mpg. I just found out at my 30k service that I have a K&N drop in filter.

 

My truck used to see 17-20 when it was stock. now i cant see any better then 16, avg of 13.

 

1. dirty/clogged fuel filter
2. fuel brand and octance
3. low tire pressure
4. non-factory recommended 5W20 oil
5. Flowmaster muffler
6. heavy foot

 

Today I went ahead and filled my tires to spec. Also changed out my fuel filter for a Motor Craft new one. I havnt driven the truck much since so I havnt been able to see if there are any changes. As for the fuel brand and octaine, I always use 93 oct. And im not really heavy on the foot, im actually a lot less than normal since I keep looking down at the mpg on the dash...

 

- Clogged fuel filter
- Bad gas
- Dirty Air filter / Throttle assembly
- Spark plugs / wires / coils not firing properly
- Do you have an aftermarket exhaust?
- V8
- Full size truck
- Stop / Go traffic
- Potentially could have a sticky brake, but i'm sure you'd notice that sooner
- When did you last change tranny fluid? Differential? You using factory spec oil?

 

Completed stock 5.4L 4x4, 15-17mpg regular driving. Don't even think I got over 17mpg on a road trip earlier this year when on the highway full time.

 

Stock 5.4 '06 Supercab 4x4 and it gets 15-16 mpg mostly highway driving. I dont beat on it but I dont drive it like a grandma either.

 

I'm getting about 16 mpg combined city/highway.
I have the sido exhaust with the 5.4,and it sounds sooooo cool that it is hard NOT to juice it.

 

mine is close to this 13.5 city 17.5 highway

04 FX4 5.4 100% stock tires at 40 psi. Highway is @ 72 mph on cruise

 

'06 4.6L, STX 4x4, all stock. 15+ in town and right at 18 on non-interstate trips.

 

06 5.4L fx4 supercrew all stock. I get 14-15mpg. I have only taken one long highway trip without towing and than I only got 16 mpg. I had heard after 20,000 miles mpg would get better after the motor broke in. Instead my mileage has stayed the same and not the motor just breaks. 48,000 and misfiring like crazy.

 

stock i saw 16mpg mixed, driving like your grandma

 

'05 xlt 54. 4x4 scab 69k miles bone stock. Got @ 14.5-15 til 50k, now get 16.2-17 in the hills and mountains of WNC. Had to learn very light, very deliberate gas pedal modulation.