I went from an average 250-270 miles on a tank (14-14.5 gallons) to about 200 miles. I just started getting this gas worse mileage recently, and i dont know why. Both my O2 sensors are pretty new, only a few months old. Im usually driving mostly city miles to and from work in stop and go traffic....the only recent mods i have done that i know should effect this are my headers.....but i thought you would get more MPG with them....any ideas?

 

I HAVE LOST 2 MPG IN THE PAST FEW MONTHS. I'm being to think they have change the gas formula again and rised the prices. I haven't figured out why my MPG has drop as of yet.

 

hard to get an honest/accurate MPG reading in the winter in most cases. Engines normally burn/need more fuel during the winter months. That on top of the equations in the fuel change during these months too.

 

I have noticed the exact same thing and i also have recently put longtubes on the car.

1st i thought it was b/c i was playing around too much I think a part it is because i let me car warm up every morning which i dont normally do in the summer months.

I thought that my 160* stat could have something to do with it b/c it is keeping the heads cooler I dont think that is the case though.

I also wonder if it has something to do with !cats and the O2 sims , the computer may be getting wierd readings that cause it to be rich

I kinda disproved that on the dyno though b/c the wideband said my af was in the 12 range

i dunno

 

WINTER GAS HAS A HIGHER VAPOR PRESSURE TO BURN MORE EASILY IN THE COLD , SO I WOULD SAY IF IT HAS BEEN MILD OUT YOUR BURNING MORE