I have a well maintained 2002 Focus with 44k miles. We were averaging 33 miles to the gallon and over the past year it has dropped down to 18. I have replaced the fuel filter and the sparks plugs. The air filter is clean. I have switched gas brands and ran fuel injector through it. The milages actually dropped by about 4 mpg after I did all of these things. I have ran about 1500 miles since doing all of this and the gas milage has not increased. There are no warning lights on and the car seems to run and idle fine. Any ideas of what is wrong?

 

I've had the same exact problem.
someone suggested the cold weather is doing it but I dont put much stock into it.

 

So I'm not the only one with this problem. Twice in the dealer and they say that there's nothing wrong with it, some milage variance is to be expected and then basically told me I'm retarded and I should stop sweating the small things. For anyone in MN, DONT GO TO TOUSLEY!!!!!!!!!!!!!! I should fire bomb it and say fix it all under warranty b%*ches!!!

Also a mechanic in the city I work for said a sensor could be stuck in one position which makes sense, but tousley said that would trip the computer, they all lie. So anyone get this fixed yet?

 

still nada
i have an intermitant EGR error though.

 

I've been thinking of pulling out the TPS, MAF, and O2 sensors and 'fixing' them myself, then the dealer would have to replace them and that could solve the problem. I guess I'll try new plugs and replace the LIFETIME air filter, lol.

 

pull your intake you may have a carbon clog.

 

Me? I ain't pullingThe dealer called and said they put it on a bench and track the wheels revolutions and says it makes 30mpg. But I say there's NO HEADWIND IN THE GARAGE!! Anyone know about that test, would it be similar to a dyno where the drum is dynamic and changes?

 

I know this is going to sound dumb, but try replacing the thermostat. That would be the most logical thing that would not trip a service engine light. For instance if your coolant is not reaching the correct operating temperature then it will cause the engines operating program to think engine is cold and will adjust fuel accordingly. Like I said it seems dumb, but it is fact. Remember years ago when people used to replace thermostat every year as maintenance? They have made most of them hard to replace nowadays and most people do not replace on regular basis any more.

 

That doesn't sound silly, in fact that makes more sense than anything I've heard from ford. Plus it's a $10 fix.

 

Kinda my thought, and the way I like to proceed into the unknown in my shop. When in doubt, start with the cheap and work forward.