bad fuel economy and power steering

[stangmach104]

hey guys, I have a '96 GT 2.4. I was getting my normal fuel economy until I took it on a 300 mile round trip. The highway economy was better than city driving and when the trip was over now instead of getting my normal 250 miles to a tank I got 165. and the tank i have now doesnt look any better. The things I have changed on the last 15,000 miles include: fuel pump, fuel injectors, spark plugs, fuel filter, fuel pressure regulator, and both ignition coils. So what could make it have this decreased economy. Also I recently got a po440 code for evap malfunction, i erased it and it hasnt come back on but I do hear a faint noise that sounds like its coming from under the coolant tank maybe the canister. And one last thing, with this cold weather in MN my power steering doesnt want to work until the car moves about 50 feet and when I let go of the accelerator there is the loud noise coming from the engine bay. I think I could be related to the power steering because it started doing that the same day my power steering started acting up. Thanks alot for any help in advance

[stangmach104]

forgot to add, power steering fluid is new.

[xeroinfinity]

CHange your O2 sensors that should improve mileage.

the p0440 could be anything from a loose gas cap to a evap system component, I wouldnt worry to much unless it continues to come back.

On your power steering, did you change out the fluid after it started acting up ?
If so thier could be some air in your system, check the fluid level when its cold, and dont overfill it.
If the above is OK , then and thiers a growling coming from the power steering pump, it could be needing replaced.

Hope that helps

[stangmach104]

forgot to include those, replaced both o2's. I guess the fast change to single digit temps could have an effect on it. The power steering fluid in about 3 months old. Im thinking the pump probably needs replacement like you said. thanks.

[J-Ri]

Originally Posted by stangmach104

forgot to include those, replaced both o2's. I guess the fast change to single digit temps could have an effect on it. The power steering fluid in about 3 months old. Im thinking the pump probably needs replacement like you said. thanks.

New O2 sensors can sometimes cause worse gas mileage. When the sensor gets old it usually will start showing a lean mixture, so the computer increases the injector pulse width. It must be possible that they can also fail and show a rich condition. I'd never seen that before, but it happened on my Beretta 2.2L. I was getting 36 MPG (manual transmission), after I replaced the O2 sensor, I was getting 30. If the old O2 sensor was white on the tip, I'd say that was the case with yours.