I do the same kind of driving most of the time, in the same conditions etc...
25 bucks of gas used to get me 240-250 miles. Now i barely get 180-200, even if that.. This was abrupt.. one tank was 250, next tank was 180, same gas, same price, same kind of driving..
what do you guys think, O2 sensor?



Problem is i have that dreaded check engine light on all the time and i can't really know if another code pops up all of the sudden. My car is also cali spec.. how many O2 sensors does it have?

anything else i can check for the crappy gas milage, what else would cause it to drop so abruptly..?

 

no I think its because of the cold season. I live Buffalo, NY and I suddenly lost 50 miles per tank. There is nothing wrong with your car (or mine). I think its the different kind of additives that gas stations use for the snow season... I bet you it will shoot back up once winter is gone.

 

New York State Just went from 2.5% MTBE to 10% Ethanol in the fuel, definitely a mileage drop. Burn more fuel to make less smog???

 

You might want to get the SES light checked out anyway... (i.e. go to Autozone and have them pull the codes)

That sounds like a pretty dramatic drop in fuel economy to me. The fuel composition changing could have something to do with it, but it still sounds suspicious.

 

Check your air filter to see if it's been clogged by dirt and check your tire pressure.


~limsandy

 

NYCE-I just read in interesting article about gas the other day in Newsday......winter gas is apparently different than summer gas-summer gas burns slower...hope that helps

PS-Jersey has oxygenated gas-maybe want to drive over and grab some

 

A loose gas cap will cause the SES light to come on, maybe the gas cap is leaking?

 

Not just NYS, the entire country. New federal laws prohibit MTBE. Law went into effect Jan 1, but most gas stations were all ethanol by thanksgiving.

I wasn't aware the ethanol caused a mileage drop. Do you know this for certain, or are you assuming?

 

Huh... so that's enforced throughout the nation now?

 

I saw the drop when my station changed, I also know that ethanol has only about 60% of the energy per lb. of gasoline.
I don't think the MTBE ban is nationwide yet - the producers have a very strong lobby.

 

I thought about the different gas thing..

but doesn't it start sometime a lot earlier? Winter gas is at gas stations in like November or so in our area, no?

This started for me in late december.


thanks for the suggestions guys..

the Check engine light is some faulty thing that many 2000s have. It has always been on but there is nothing broken. Even with the previous owner. The problem is that I can't know whether something else goes wrong until i randomly check the codes, because the light is always on anyways, whether i have 1 or 5 codes.
I'm going to stop by autozone one of these days.

 

Winter gas with 2.5% MTBE started in October. Since New York banned MTBE effective 01/01/04, stations started switching to 10% ethanol winter gas in December.

 

I noticed an MPG drop about 2 or 3 weeks ago in my other car, a 95 talon TSi. I chalked it up to winter temps at first but that doesn't make sense. I'm down about 12%. No CEL but that can happen as the car ages and the o2 loses efficiency. To back that up even more, I just had emissions done on the car and CO is like WAYYYY up. It's burning too rich @ stoich. Last year it was like 2, this year it went up to 134 PPM and almost failed.

NYCe MaXiMa, you're down about 24%, that's probably o2 and may not even throw a code. o2 may still be ok diagnostically to the ECU but it's starting to fade. I don't know what exactly happens to an old and used up o2, but if the voltage signal starts to drop (which it's supposed to do in the precense of oxygen) it makes the ECU think there is oxygen in the exhaust. The ecu increases injector pulse width until voltage gets back up. If the o2 is sending less voltage than it should the car will go rich, use more fuel.