Major gas mileage drop
 

Hey, I am new to this forum thing but my family uses Doo talk for our snowmobiles and it seems to work for them so here is my try.

I have a 2006 tC, its automatic and has 75K on it. I got it brand new in 2005. I drive drive pretty agressively but havent changed the way i drive recently. Over the past month or so my gas mileage has dropped ridiculously. i have figured it out to be about 19 highway and14-15 in the city. i used to average 25ish. I have tried octance booster and have switched to using premium gas. My mechanic said that anything he could think of should be triggering my service light to come on.

I hope someone can help me out cause i am getting really ____ed that my buddy with a 94 wrangler is getting the same gas mileage as me.

try tune up? clean the throttle body? check air filter?

clean maf sensor maybe.

Welcome to the club. Member #76,543

or spark plugs too.. maybe the O2 sensor but you should be throwing some check engine for that.. Try resetting your ecu too, it may help to start a new fuel trims for fuel economy

^^ X2... that's what I would check first... then if that doesn't help, with it being wintertime.... a lot of fuel stations across the U.S. change their fuel mixture they sell during the winter months...and it equals really crappy mileage. I have found in my area that there are a few independent Shell stations that do not add the ethanol to some of their fuel grades during the winter. I don't think this is just unique to SHELL stations... as every major "brand" gas-station is usually independently owned/operated. (franchise).
So you might take that into consideration before you go digging into your car too much.
Especially with the time frame you mentioned is about when most stations start introducing the ethanol into their fuels.

Check your oil, change it if it doesn't feel slippery between your fingers and run regular. Check your tile pipe if it is sooty then you have some fuel problems and maybe your O2 sensor is going or MAF cleaning and of course your plugs.

It might be a longshot, however people tend to leave their vehicles idling alot more, and tend to keep them on longer during the winter due to the cold. Is it possible that due to a colder winter, you start it and let it run for a bit when you get in? Doing so twice a day, daily could result in using more gas mileage. Or that you stay in it when going places and leave it running? Although this might not be the whole issue, it could be part of it.

i've had mine drop to 14-16mpg before, it was a dirty MAF sensor. Cleaned it with CRC's MAF sensor cleaner popped up to 24-25mpg. But the winter gas is terrible! I think they're using more ethanol than usual in the gas lately. Which would account for the 5mpg drop i've seen in my own!sigh :(And yeah, everything is tuned up and aligned.