I just started recently getting completely terrible gas mileage. Im getting about around 15-20 miles to the gallon, and around 250 to a tank. It just started doing thing within the past month, and i have made no modifications to it. Any suggestions? Checked the oil, its fine. The car seems to be running normal, just getting bad mileage.

 

I would run seafoam thru it first. If that doesnt help then maybe a new o2 sensor is in line.

 

You might want to do a few treatments of seafoam, spaced out. It can jar debri loosewithin your engine,but then deposited elsewhere in the engine. Don't know what kind of car you have or how many miles but I'm guessing atleast over 100,000.

If you add it to your oil crankcase I would recommend doing it a few 100 miles befor you change it. Then add synthetic oil.

Add a little to the intake manifold via the fuel regulator hose(vac line). Just tiny bits from a cup, or it will stall, and go through the engine too quickly. Then follow instructions on bottle.

You might want to just run fuel injector cleaner to the gas tank. The expensive stuff like chevron no cheap stuff. You can use the seafoam aswell but make sure you do it on a full tank and recommended dose.

If your still getting bad gas mileage you could always replace a few things, fuel filter, pcv valve, air filter.....Also always get your gas at a well known place, mobil, Irving, etc. You never know what kind of crap they cut it with!!!

 

alright, i put got some seafoam, and a new fuel filter, will have to see if anything gets better from here. Also, its a 93 Civic EX with 195,000 miles. Another question... where are the o2 sensors, and how do you remove them/test them?

 

I know one o2 sensor is in your exhaust manifold, and I think there's another in the cat. I'm not sure about the cat one though... Wouldn't a bad o2 sensor throw a CEL though?

 

yes it will.

 

no there is only one on the manifold that's it. otherwise i would be throwing CELs left and right cause i don't have a cat

 

ok, well i dont have a check engine light... i just replaced the fuel filter today, and put the seafoam in the gas tank. Any other things i can do?


edit: also... i put a new AEM dryflow air filter on my SRI not too long ago... but the bad gas mileage didnt start exactly after i put it on, maybe around a month or so after, though. i doubt this is the problem... but im just throwing it out there.

 

No matter what the companies tell you when you open up the intake and put on a better flowing exhaust gas mileage always takes a hit.

 

Oh but you def shouldnt be gettin 15-20 mpg