100-120 miles on a full tank of gas!!! WTH??
OP, don't listen to 90% of what ppl say here. Most of them are completely wrong, even though their intentions are good. You will save money in the long run by taking it to a reputable shop that can diagnose the issue for you. If you do decide to throw an O2 sensor in it, just replace the one in the O2 housing right below the turbo....the one in the cat will not affect your fuel mileage. The MAF sensor can also reduce your fuel mileage, but you would most likely notice other driveability issues. Personally, I would vote for a leak in your intake manifold between the throttle body and the head. This will cause a high idle and set the code you are getting. Since there is extra air entering the engine, extra fuel will be added to compensate, and reduce your mileage. But like I said, you will most likely save money in the long run having it diagnosed properly.
your an idiot buying a Evo for GAS mileage was where you went wrong! you should have had a reason like loving one of the most powerful 4 cylinder engines on the planet as a reason to buy the car not gas mileage...but anyway something is wrong you should be getting more then that there a alot of things that rob gas mileage tho...old oil, how much u use the AC, air filter being dirty as *****, and the biggest of them all is Boosting it will burn gas like nothing..more air needs more fuel didnt mean to be a d*ck in the start of this post either im just saying
I am not rich by any means, but when I buy a car, which tend to do ever year lol.. I change the plugs, ALL fluids and belts and for some odd reason the clutch 
. that way you know ur maintance is DONE. but im pretty hard on my car, tuned at 400ish and I boost it alot. I still get 230-250 miles on a tank.
Could be tire pressure and alignment ect..
. that way you know ur maintance is DONE. but im pretty hard on my car, tuned at 400ish and I boost it alot. I still get 230-250 miles on a tank.Could be tire pressure and alignment ect..
I had this same mpg issue and it was due to my egr hoses had blown off. Some people have already mentioned that but only refered to them as hoses around the throttle body. Please check those as it will affect your idle also.
your an idiot buying a Evo for GAS mileage was where you went wrong! you should have had a reason like loving one of the most powerful 4 cylinder engines on the planet as a reason to buy the car not gas mileage...but anyway something is wrong you should be getting more then that there a alot of things that rob gas mileage tho...old oil, how much u use the AC, air filter being dirty as *****, and the biggest of them all is Boosting it will burn gas like nothing..more air needs more fuel didnt mean to be a d*ck in the start of this post either im just saying
he says he hits 10psi between shifts on a stock evo. still should be getting roughly 17-20 mpg even with the accessories on.
op i say take it to get checked in.
