95-del-sol

Hey guys, I've got something I need help figuring out. my gas mileage has dropped. a lot. normally my del sol S would get about 300 miles per tank. give or take 15miles given different driving conditions.. anyways, i am now barely getting 200 miles per tank. i've lost 100 miles per tank of gas. I don't know why, or where to even start to look under my hood. also I'd like to point out that this was not over a period of some time. This drop in mileage happened instantly out of nowhere. I even started driving no faster then 70 mph on the freeway most the time. i used to go about 85-90, sometimes even 100 and still got good gas mileage around 275 per tank if i did it a lot.

so if any of you tech guys are knowledgeable in this area please respond asap!!

thank you in advance for your tips.

strategy400

Tune up required? Something dragging? High mileage? Something clogged?

95-del-sol

as far as i know none of those, maybe about 4000 miles ago i had replaced the plugs and wires, oil at about 2.5k miles ago. (head gasket blew a few months back) and i still had my 30+mpg after i fixed the car.

95-del-sol

nothing dragging, mileage is about 155K. as far as i know nothing clogged, i mean, i could go for a new air filter but its not all that dirty. its pretty cheap so i coul just throw one in and get a new fuel filter too for starters.

crazyhouse2011

Is there a film of black soot above your exhaust pipe on the rear bumper? Keep an eye on that.

95-del-sol

no there isn't. what would that indicate?

crazyhouse2011

YOUR ENGIne running rich. Which would be another common symptom of a failed oxygen sensor. Rich engines like to guzzle gas, ie poor mileage

strategy400

Swapping the o2 might help. Is it getting to operating temp?