my 94 teg LS drinks gas now that is is cold outside, i am getting a 30% reduction in fuel economy, i had the same problem last year & changing the air filter did not really help

 

well if most of your driving is done when the engine is cold, like if you only make really short trips, then the cold can seriously affect your fuel economy.

 

When it's cold your car will run more lean. Just start shifting at 3k rpms.

 

Lean means less gas. He wouldn't be loosing fuel economy if his car was running lean.

 

Are your spark plugs good? Has your fuel filter been changed lately? What about your tire pressure the cold affects that. Just some ideas

 

are you sure its because of the cold? have you been up to date with tuneups and regular maintainence?

 

i changed the plugs over the summer, i wonder if it is a fuel pump or fuel filter problem cause i don't think those have ever been changed

 

Get a feul pressure regulator and a air feul ratio guage. When it gets cold outside you will have to adjust your feul pressure. Its just like running at the track you have to tune your car for the conditions.

 

When the engine is cold it runs a lot more rich, and it's not running efficiently until it's warm. If you're making trips that only let the engine get up to temp as you arive at your destination, that explains your mileage problems completely.

 

A/F ratio guages read the voltage off the stock oxygen sensor. Data from the sensor is only used by the ECU when it is in open-loop mode. It switches over to open-loop at something like 74 percent or greater TPS and some RPM. Out of that range the voltage reading from the sensor jumps all over the place, which is totally inaccurate. Unless you have a wide-band oxygen sensor, any a/f guage is more of an "oh crap I'm leaning out" warning light on WOT runs than a tuning tool. Secondly, a fuel pressure regulator can only bump the whole fuel curve up or down a bit. It's not a very precise method of adjustment. The best way to tune is to get at the fuel and ignition maps inside of the ECU.

The most probable reason the car eats gas when it's cold out is the weather. Cold air is more dense which means more oxygen. The engine can then use more fuel to burn that extra oxygen, hence the higher gas consumption.