For the past month 1/2, my gas mileage have decreased dramaticaly. My normal commute is 80% highway, 20% city. I normally get around 28mpg. But now, I get around 23.5mpg with very little vtec. I tried resetting the ecu with same result. Could it be bad fuel pump, injectors, spark plugs?

 

More ethanol in the fuel mix? Where do you live?

 

did your car sit around for any long period of time?..1-2 weeks not starting it at all?

 

I live in NJ. I don't think we switched over to winter gas yet. But even in the winter, I noramlly get around 26-27 mpg

 

maybe cheaper gas prices so you are filling up sooner? when you let the tank run dry, the decreased weight gives up better gas mileage. now with cheaper gas prices a lot of people are filling up regularly in smaller shots rather than pumping in a full tank. more frequent fill ups would mean more weight (gasoline) as the engine has to tow it. or, how 'bout with the cheaper gas prices you are psychologically not as conservative as you were say two months ago with gas consumption and are actually depressing the throttle more?

 

check your plugs, air filter and tire pressure.

 

take the dead prostitute out of your trunk.

 

That is the best place to start.

 

Check o2 sensor as well

 

I don't know why, but as temps drop Hp increases and mpg decreases.