Do me a favour, check and see (or feel ) if you have black soot in your tail pipe on the 4.6 V8. My truck passes emisions with ease but drinks gas and the tail pipe is sooty.

 

Sounds like you're overfueling the cylinders and not getting a complete burn of the air/fuel mixture. This is not good at all as it leads to valves sticking and fouled plugs.

Check your O-2 sensors to make sure all of them are sending the proper signal (they tell the computer how rich or lean to run the fuel mixture). Then check the EGR valve assembly to make sure it's not stuck. Most AutoZone stores will check them for free with a code reader that plugs into the diagnostic point.

Let us know what you find out.

 

it is most likely normal for the soot. These trucks run a little rich fron the factory. Stick to a good quality gas and enjoy. BTY mine has the black soot too.

Regards

Jean Marc Chartier

 

No codes (I have a reader) truck runs ok, can't say good all round 'cause 12 mpg is crap, but its always been 12 mpg. 95000 mile to date. Mostly fast local street trips of 20mile+ Where's that small diesel Mr Ford?? I ain't buying an '04+ till then!!