[LMagenis]

For the last 5 years, my MPG has been in the 25's. Within the past 3 months, I've had a steady decline to about 20/21. The car has 30800 miles on it. The air filter was cleaned at 30K, fuel filter replaced a year ago (don't know the mileage off hand), tires are fine, & my driving hasn't changed.
Should I replace the plugs and wires, even though I'm not at the normal mileage for this? What else should I check?

 

[Moraki]

Theres alot of things you could check.

Yes if your not firing on all 6 cylinders your milage will drop alot. And if the plugs themselves are gunked up they might not be firing properly either. Maybe replace your plugs and wires, or check them for spark.

Possibly clean your UIM, and LIM, check to make sure your secondaries are clean and operating correctly also.

Might not hurt, and its pretty easy, to throw some fuel injector cleaner in you tank.

Other than that youd have to trouble shoot it, possible but not likely your computer is going crazy. Maybe the intake is blocked before the filter? I assume you mean a stock intake. But those are just shots in the dark....and not very likely. you could come up with a ton of those

 

[Funkboy316]

something as simple as tire pressure can also effect gas mileage believe it or not

 

[Saleen Cougar]

replace the fuel filter any way to be on the safe side.(there only like 9 bucks) and as funkboy said check the tire pressure

 

[wadespencer99]

I'm dealing with the same thing.

My tire pressure is fine, I just replaced the fuel pump (dying returnless) and put in a new fuel filter, precats are gutted, air filter is clean, cleaned LIM and installed Max extrude honed SVT UIM and SVT TB in May. Plugs were changed end of last summer before the car was put up for the winter.

The best I've gotten all year is 22 on a trip, and that was trying for the good mileage. Other than plugs and wires, I'm at a loss of what it could be, and I will be anxiously reading this thread for ideas

 

[Saleen Cougar]

Originally posted by: wadespencer99
I'm dealing with the same thing.

My tire pressure is fine, I just replaced the fuel pump (dying returnless) and put in a new fuel filter, precats are gutted, air filter is clean, cleaned LIM and installed Max extrude honed SVT UIM and SVT TB in May. Plugs were changed end of last summer before the car was put up for the winter.

The best I've gotten all year is 22 on a trip, and that was trying for the good mileage. Other than plugs and wires, I'm at a loss of what it could be, and I will be anxiously reading this thread for ideas

i found your problem. (gutted pre-cats) the duratec 2.5 loves back pressure, buy gutting your pre-cats your exhuast is more free flowing, thus less back pressure. which leads to lower mpg in the duratec 2.5

 

[MaverickFlyer]

Originally posted by: Fearthisescorti found your problem. (gutted pre-cats) the duratec 2.5 loves back pressure, buy gutting your pre-cats your exhuast is more free flowing, thus less back pressure. which leads to lower mpg in the duratec 2.5

I don't know about that, I noticed better gas mileage after gutting my pre cats, installing a MagnaFlow Highflow cat, and 2 1/2" MagnaFlow Muffler! :shrug:

 

[LMagenis]

my tires are fine (original post)

I'll switch out the plugs and wires, and clean the uim.

Replace the fuel filter--ok, it's pretty easy to do, as long as your strong enough to attach the clips. I'll get the husband to do that.

I have a KKM filter. It's still a pretty shade of pink.

fuel injector cleaner goes in at every oil change. I'll throw some in today since I filled up yesterday.


Thanks for the ideas! Anyone else?

 

[wadespencer99]

I just gutted them last weekend....the mileage didn't change one way or another.

 

[silverkat]

Maybe it's too early for you, but I had the same problem with 106,000 miles. I was getting 22 on the highway. I replaced the bank 1 sensor 1 O2 sensor and the DPFE sensor. Now I get 25+ and it cost me $100.

 

[99Elimin8r]

i hope silver cat sees this but did you have any cels come on in the meantime before you changed the sensors? cause i am having the same problem but no codes....

 

[Blackcoog]

Don't rely on the trip computer to tell you mileage. Make sure you check it yourself to see if it is accurate.