Mysterious Gas Millage

[MelectroK]

All winter long I have been getting 20.5 MPG MAX. And I do mean max mostly it was bearly 20. Now, on this tank, all of a sudden gas milage was 22.5 MPG. The only diffrence is its now 50-60 degrees out as apposed to 30-40 degrees, and I switched out my snow tires for all seasons.

Does anyone have a resonable explination for this?

 

[qiksho]

The differences in the size of your tires are?


Does your cooling system run hoter or colder?
If it wasn't up in the normal part of the gauge its possible you were always running in warm up mode - causing a rich condition, using more fuel

Thats my two suggestions :corn:

 

[MelectroK]

Tires are the same size but the tread is way less agressive. The car ran plenty far up in the normal range most the time, even though it is slightly higher now.

 

[1995mtxsho]

Heat! The AC pump is engaged when the heat is on. Correct me if I am wrong.

 

[platoribs]

Heat! The AC pump is engaged when the heat is on. Correct me if I am wrong.

Shouldn't be.

 

[SHOtimer]

Heat! The AC pump is engaged when the heat is on. Correct me if I am wrong.

The AC compressor runs in every position of the EATC except 'floor', 'vent', and 'off'.

The mileage I would attribute to colder weather. The colder the weather the richer the car must run to stay at temp, and takes longer to warm up in the mornings. Many people on this board have observed better MPG in summer than winter.

Doug

 

[SHOstoppin93]

the engine I believe runs a richer mixture because of the more dense air and to keep the proper air:fuel mixture, the computer must add more fuel in cold temperatures. Once the ambient temperature warms up, the less dense air requires less fuel to maintain that certain ratio. Also the snow tires are a softer compound, the harder the tire compound the less rolling resistance.