How To Improve MPG

[endlesszeal]

Well my gf has a 93 4 door civic dx. she currently gets a messy 240 miles between fill ups. i think her tank is around 8-10gallons and i thought dxs get about 30mpg in the streets, thus she should be getting AT LEAST 300. what could it be? we changed the oil and filter, air filter, and poured some injector cleaner. would replacing her fuel filter help? what else could it be? the subwoofers?? i doubt it. anyway ithas no mods except its lowered on stock 13 inch bling blings with 160ishk miles.

 

[Crix]

tire pressure.

 

[cheese9988]

Could be alot of things, o2 sensor, tire pressure, suspension, your foor on the gas pedal etc.

 

[94RedSiGal]

City driving makes the gas mileage suck. A/T or M/T?

 

[swanny]

Fuel filter, plugs, tire pressure, o2 sensor, injectors etc

 

[Greybridge]

Since endlesszeal started this topic and the search engine didn't help maybe the same problem i'm having can help him out...if i find out the problem.
Here's my deal, 91 crx si mpg's dropped to 25 mpg after average of 32 before the engine went. Did poor man's d16z swap aka pm6 d16a dizzy, intake, fuel rail, d16z fpr. Still 25 mpg then tranny shot about 3 weeks later swapped with japan import with low mileage and mpgs went up to about 26-27. I can see a bad tranny pulling down the mpg abit like this but the main problem still exists.
New cap/rotor, plugs/wires, fuel/air filter, O2 sensor, oil/filter since or during the swap and none of that fixed it. If it's the fuel pump wouln't that use less gas and loss of power? Haynes manual suggest fuel injectors as a possibility but those can be expensive to buy and not fix the problem. Another thing is right after the swap the car burned rich for awhile but the smell of gas from the exhaust is gone so figure that is just from the engine change.
Sorry for the long post just wanna cover everything to narrow down this annoying problem. <_<

 

[projectxspeed]

Have you tried resetting your ECU?

 

[CRX-YEM]

depending on where you live the in the winter they modifiy the gas formula to work better in the colder months. I'm in CT and drive a 91 CRX , in the summer months I get about 300-350 miles to a full tank of 87 octane. in the winter I only get about 240-260.

 

[Greybridge]

Yes reset the ecu after the swap but not after the tranny, live in NC winters fairly mild here.
Think I saw someone selling stock injectors here for a nice price might as well give that a try.

 

[92civicb18b1]

stock injectors are cheap just make sure you get obd1, i think obd2 with work also.