Drinking Gas

bad O2 sensor will do that

if you can get a 'real' scan tool, watch the O2 volts

each sensor should switch back and forth, above and below 0.45 volts

if one is stuck on the low side, it is telling the ECM that there is a lot of free O2 in the exhaust, and the ECM adds gas

I assume by a 'real' scan tool you mean a good one? I'm not sure what my buddies got until I borrow it. I may have to get it read some where or buy a descent one. Any suggestions for a good code reader?

Thanks Brian

If you live in an area of the country that "oxygenates" the fuel, you may notice an decrease in mileage as well. It happened to me every winter in NY, NJ when I lived up that way.....may seem like an "overnight problem"

That's interesting, I live in Cincinnati Ohio and we have just had the weather change to cooler weather in the last few weeks. But as far as the fuel being oxygenated, wouldn't that be to increase the burning efficiency?

Thanks Brian

I believe California has some of the worst gas in the country (due to EPA regs "Helping" then environment) Get about 12 in the summer, 10 in the winter. Its been doing this for as long as I have owned the truck.

I love my old truck though, 1971 F250, 6 MPG, w> If you live in an area of the country that "oxygenates" the fuel, you

You would think so, but it has more to do with adding a bit more alcohol I think in order to bring polutants down in the winter months with the low weather ceilings and all. I honestly would have to do a bit more research on the scientifics of it.

But I do know that I used to get worse gas mileage for sure, and was very evident in shorter trips around town. Longer trips tended to be just slightly less, but I chalked it up to having to stop and go when there was a winter accident on the roads....

efficiency?

There is a site about the effect of increased oxygenates listed under "gasoline FAQ" by Bruce Hamilton that states: " However, on vehicles with engine management systems, the fuel volume will be increased to bring the stoichiometry back to the preferred optimum setting. Oxygen in the fuel can not contribute energy, consequently the fuel has less energy content. For the same efficiency and power output, more fuel has to be burnt, and the slight improvements in combustion efficiency that oxygenates provide on some engines usually do not completely compensate for the oxygen." I think that's pretty much it in a nutshell.My mileage here in Cal always takes a big hit in the cold months. Best....Brian O.

OK,here:

Best....Brian O.

Thanks for the info, I did check the trucks computer and no error codes. So I've either got a weak / bad oxygen sensor before the catalytic converter or it could the gas.

Brian

That URL doesn't seem to exist.

William The Guesser

Looks like he changed it .It's now

Also question 8.1:

"The most likely reason { for low mileage} is that your local garage switched to an oxygenated gasoline, and the engine management system compensated for the oxygen content, causing the fuel consumption to increase significantly." Brian O.

I guess the reason I don't feel that it's the fuel is my 1994 Chevy Z34 seams to use the same amount of fuel as it always did. The truck was noticeable just by how often I had to refill, I then did a mileage check and saw a degrease by 3 mpg.

Brian

====== I wonder if they studied the effects of getting 2 mpg less on the enviroment? It seams like you would want a vehicle to get the best mileage for a cleaner overall tailpipe........And also, whats the deal with the vehicle having to run RICHER because of the fuel? The whole thing sounds like an oil company conspiracy. "Ok, it will burn cleaner but it will cost you more per gallon and you will need more of it per mile".....Hmmmmm.

Oh, and if your truck's O2 sensor and plugs and fuel filter have 67K on them, change them all (It's due:).

plugs, O2 sensors, air cleaner, fan belt, dist cap and rotor, trans fluid, and diff fluid are all less then two years old (15,000 miles max) Thinking about a set of MSD wires... but how much would that really help?

Here is something else Im thinking about.

Well I may just have to buy into the oxygenation of fuel theory. I've filled up twice since this posting and both times I'm back up to 14.6 MPG and 14.4 MPG. And for the winter weather this is about right for the truck. I do remember getting gas at a station that I rarely ever go to about three weeks ago. I usually get my gas from a United Dairy Farmers store, they have Mobile fuel and I've always had good luck with that. So I guess that I need to check the mileage a few more times and maybe that's all it was.

Brian

Air cleaner and tranny fluid sound like they are due. Fram air filters are just as good any anything, and so cheap I just do them w/ my oil change - change the oil filter every time too. Cheap insurance...

GMC Greml> >> I believe California has some of the worst gas in the country (due

I'm just curious to ask since you guys mentioned the strict epa regulations in California, if you buy a brand new Chevy with a 5.3 Liter in Cali, and then go to Michigan and buy the exact same vehicle, is there going to be any difference in the two, emission control wise? I was just wondering if you moved from another state to cali, would you have to get your vehicle an emission test? Its a good thing Mich doesn't require emission testing, I think half the population would fail.

regulations

GM and many other manufacturers have a 50 state emission rating for a couple of year now. Usually it's stated right on the vehicles window sticker as standard equipment.

Brian