Dumbfounded

[bizoneoeh]

I was kind of wonderin myself because I filled up on Sunday night and I'm below a 1/4 tank now. It usually usually last a full week.



it's all good tho because at the local grocery store here, they give you like .60¢ off a gallon if you spend over $90 bucks. You have to buy the gas from their gas stations of course but they usually have cheaper gas anyway. Do any of the stores offer that where you guys live?

 

[Lopez619]

^^^ safeway does that also but i've been told that they have crappy gas, theres also a exxon that gives you like 12 cents off if you buy this thing called a speedpass

 

[RonJ]

The premise of this thread is that winter gas blends reduce gas mileage, but this is not the real reason for lower gas mileage in the winter. The primary cause is actually due to cold temperatures that greatly lengthen the time for the engine to get hot. And you say why would this be important? And I would say good question. Until your engine gets hot, O2 sensor signals are ignored by the ECU and the ECU instead runs the engine on a predetermined very rich air-fuel ratio (high fuel consumption). A very rich fuel mix is required when the engine is cold because cold liquid fuel only partially vaporizes to the gas state in a cold cylinder. This is relevant because gas vapor not gas liquid can produce the explosion necessary to move the piston in the cylinder. In contrast, when the engine is hot, the ECU now "listens" to the O2 sensor outputs and uses the information to tell the fuel injectors to inject the exact amount of fuel to yield the optimal air-fuel ratio (14.7:1) (minimal fuel consumption).

The take-home point is that the longer the engine takes to reach normal operating temperature, the lower your gas mileage will be. Thus, the lower the winter temperature in your part of the country, the lower your gas mileage will be.

 

[Lopez619]

^^^ smart ass
just kidding nice explanation :

 

[JohnS.]

The premise of this thread is that winter gas blends reduce gas mileage, but this is not the real reason for lower gas mileage in the winter. The primary cause is actually due to cold temperatures that greatly lengthen the time for the engine to get hot. And you say why would this be important? And I would say good question. Until your engine gets hot, O2 sensor signals are ignored by the ECU and the ECU instead runs the engine on a predetermined very rich air-fuel ratio (high fuel consumption). A very rich fuel mix is required when the engine is cold because cold liquid fuel only partially vaporizes to the gas state in a cold cylinder. This is relevant because gas vapor not gas liquid can produce the explosion necessary to move the piston in the cylinder. In contrast, when the engine is hot, the ECU now "listens" to the O2 sensor outputs and uses the information to tell the fuel injectors to inject the exact amount of fuel to yield the optimal air-fuel ratio (14.7:1) (minimal fuel consumption).

The take-home point is that the longer the engine takes to reach normal operating temperature, the lower your gas mileage will be. Thus, the lower the winter temperature in your part of the country, the lower your gas mileage will be.

Didn't know that. Good stuff . Thank God I changed my t-stat earlier this year. Even when it's 5 degrees out, my car takes roughly 10 minutes to completely warm up. It used to take at least a half hour for the needle to be at operating temp.

 

[Kswest]

The premise of this thread is that winter gas blends reduce gas mileage, but this is not the real reason for lower gas mileage in the winter. The primary cause is actually due to cold temperatures that greatly lengthen the time for the engine to get hot. And you say why would this be important? And I would say good question. Until your engine gets hot, O2 sensor signals are ignored by the ECU and the ECU instead runs the engine on a predetermined very rich air-fuel ratio (high fuel consumption). A very rich fuel mix is required when the engine is cold because cold liquid fuel only partially vaporizes to the gas state in a cold cylinder. This is relevant because gas vapor not gas liquid can produce the explosion necessary to move the piston in the cylinder. In contrast, when the engine is hot, the ECU now "listens" to the O2 sensor outputs and uses the information to tell the fuel injectors to inject the exact amount of fuel to yield the optimal air-fuel ratio (14.7:1) (minimal fuel consumption).

The take-home point is that the longer the engine takes to reach normal operating temperature, the lower your gas mileage will be. Thus, the lower the winter temperature in your part of the country, the lower your gas mileage will be.

Good info Ron, I still have to wonder though, I live in a waaaay colder climate last winter and still got almost 300 to a tank. I begin to wonder if there is something more deep seeded than just op temp or winter gas...

 

[RonJ]

Good info Ron, I still have to wonder though, I live in a waaaay colder climate last winter and still got almost 300 to a tank. I begin to wonder if there is something more deep seeded than just op temp or winter gas...

As you know, there are a multitude of possible causes for reduced gas mileage. If you don't have any CEL codes, I'd recommend that you start by doing a basic tune up (=replace plugs, wires, cap, rotor and check the ignition timing), if this has not been done recently.