Cold weather = really bad MPG please help

[TougeTune180]

I have a big problem and i dont know what is possibly causing it...when the weather is relativly cold (40 deg F and colder) i get roughly 5 mpg but when the weather is warmer (40 deg F+) i get close to 21 mpg so any help you guys can give would be awsome thank you very much

[xero1]

any code from ecu? there is only a 5 mpg difference between cold and hot days on my sr20det.

[goj_cloud]

try checking out your o2 sensor

[TougeTune180]

my o2 sensor is working fine, so im thinking that it could be MAF or possibly injectors going bad maybe??

[redtop91]

Check your fuel lines! They get brittle and contract in the cold. They might have cracks.

[jdm_master_X]

how quickly does your car warm up?

in cold climates engines tend to run a little richer to heighten the temperature of the engine to normal operation.

frozen fuel lines will cause tremendous hesitation upon warm up. i highly doubt your fuel pressure regulator froze up either.

im inclined to believe its your coolant temp sensor not effectively sending signals to the ECU for temp readings. an o2 sensor heats up internally, and the engine would run rich from the o2 because the engine is physically running lean.

[sunnys14]

frozen fuel lines will cause tremendous hesitation upon warm up. i highly doubt your fuel pressure regulator froze up either.

wow frozen fuel lines? unleaded gasoline has a freezing point of -97Fdegrees. anyways... yeah like he said, check your coolant temp sensor.
Modified by sunnys14 at 11:19 PM 12/10/2006

[xero1]

what kind of gas are you using? do you have a working diagnostic connector?