Contour Enthusiasts Group Archives Forums General Troubleshooting Gas being eaten like crazy

I too have noticed my mileage getting worse lately. One thing you all need to remember too is that the gas companies (for the most part) temperature correct their gas (to 15Celsius here in Canada). What that means is when the temperature is below 15 and the pump says you got 50 litres, you really got less than 50 litres. The opposite is true in the summertime when the temp is above 15 Celsius (ie. you really get more than 50 litres). This'll help explain why if you track your mileage tank to tank, it's gone down, but won't explain why a full tank won't go as far as before (afterall, you still stop when the pump nozzle recognizes your tank is full). I'm at a loss to explain that, although I've always wondered if the winter additives in the gas affect it some how??

I would think that a faulty/failed coolant temp sensor would trigger a CEL, and a stalling vehicle when at operating temperature. At least that is what happens on the GM vehicles I owned.

The PCV valve is generally common culprit for excessive oil consumption, but I am not sure about gasoline.

Crafty neighbor/co-worker: possibly?

Hole in the fuel line: Would definitly smell it

Definitely check the tire pressure.

Oil companies have over 90 different blends of gasoline that they have to shuffle depending on the seasons of the year and the region of the country (in the U.S., at least for EPA reasons.)I have noticed 2-3 MPG changes because of the blends for the different seasons.

The car could be stuck in the "OPEN LOOP" mode, which would make it run rich all the time. This would NOT necessarily trigger a CEL, either.

Timing: possibly, but that requires a computer reprogram to reset (no distributor anymore.)

The oil viscosity is based on the "pour point" of the base stock and the amount of polymer chains used to increase the viscosity when warmed up. The viscosity index (VI) is such that for a given multiweight oil (i.e. 5w30), the oil will increase its viscosity by literally "uncoiling" the polymer chains at a set temperature. This temperature is a fixed value and is controlled/determined by the API.

Improperly gapped spark plugs can cause mileage degredation.

Anyway, just some food for thought. Please feel free to refute at will.

David

Actually, it's the other way around.

The meter at the gas station measures volume. The pump is calibrated at a standard temperature (15 C), but metered volume is metered volume regardless of temperature. The fuel may subsequently warm up or cool down in your car's tank, which would change its volume, but you got close to the indicated number of liters at the time you filled up.

If you fill up on a cold morning, the density of the gasoline is higher, so you get more kg per liter of fuel, but the blissfully ignorant meter can only tell you how many liters you took.


Garrick

Not sure what you mean by "on a cold morning, the density of the gasoline is higher"?? Doesn't gasoline expand in the heat and contract in the cold??

LBVSVT wrote:

Not sure what you mean by "on a cold morning, the density of the gasoline is higher"?? Doesn't gasoline expand in the heat and contract in the cold??

  Same mass, smaller volume = higher density.

ive noticed recently that im getting worse gas milage too.. before around 300 miles for a full tank of gas, now its down to 200-225 for a full tank.. could it be my new tire size? i have now 225/50/16 on stock rim

Hehe...I just reset my ECU (Since I added a Borla) and this week I got 107 miles on 1 tank of gas.

NOW THAT SUX!!!


I hope it will get better.

Later

It could be your gauge mine did the same thing pay attention to how much gas you are putting in mine would be on empty fuel light on but only take 9 dollars to fill up had to replace the cinding unit works fine now just an idea?

I don't think that the tire size you have should make that much difference. 225/50/16 should not slow your speedo/odo more than 2-3% (5% maximum.)

In fact, I just replaced my OEM 215/50/16's with 205/55/16's (98-99 OEM size) and the difference in rolling circumference from the old to the new was 1.62% (slower reading), and my fuel mileage actually improved from 28 to 30 on the highway doing a steady 75 mph.

NITROS -- bad O2 sensor? Try disconnecting your computer and such. Perhaps the system is getting outta whack. 180 miles per tank ain't that bad -- I get about 200 and I accelerate hard a lot.

The guages can be inaccurate. If you park on a slope or whatever it changes, and even if you corner hard or floor it a lot, the gas sloshes around.

Or maybe someone is siphoning your tank!?