[Matt D]

Hello,

My '04 XT has about 60k miles on it, and I've been getting terrible gas mileage on the past 2 tanks - like 12 or 13mpg. I use 93 octane gas all the time and have replaced filters/plugs when I was supposed to.

The main possible cause is that all my recent mileage has been about all city driving and about 1% highway. And most of that driving was when we were clobbered with a couple of 18"+ snow storms and the roads were in terrible shape (think 5mph driving). I understand this might be "winter gas" for whatever that's worth.

But I think it's more than that and have been told that cleaning my MAF sensor might help. Problem is, I'm not sure I have an MAF or MAP. I've read Peaty's post on it but to be honest I'm still a little confused. If I do have an MAF, I'll go to the autostore and buy MAF specific cleaner and spray it down to see if that helps.

Any other suggestions?

Thanks

 

[funkymonkey1002]

All turbo models are MAF based.

How many miles on the air and fuel filter?

Could also be front o2 sensor.

 

[sirwilliam]

yeah, so many things that could be happening....

-Dirty maf sensor (FIX: Spray cleaner or replace)
-Bad spark plugs (FIX: Replace)
-bad fuel (FIX: add dry gas)
-Dirty air filter (FIX: Replace or clean)
-Dirty fuel filter (FIX: Replace)
-bad o2 sensors (FIX: Replace)

That is to name a couple.

NOTE: Also, changing to taller tires (i.e. increasing tire/section height).

 

[Matt D]

Thanks guys.

I replaced the spark plugs, air filter, and fuel filter about 10k miles ago and these problems started within the last 1000, so I'm going to rule those out.

Sounds like I'll try cleaning the MAF sensor then.

How hard and expensive is it to replace the O2 sensor?

Edit: found a great tutorial on scoobymods:
http://www.scoobymods.com/front-oxygen-sensor-o2-t9398.html?p=37746

 

[funkymonkey1002]

Thanks guys.

I replaced the spark plugs, air filter, and fuel filter about 10k miles ago and these problems started within the last 1000, so I'm going to rule those out.

Sounds like I'll try cleaning the MAF sensor then.

How hard and expensive is it to replace the O2 sensor?

The front O2 usually runs about 150$, best to get an OEM one. Its easy to replace as long as its not rusted in (its just threaded into the exhaust pipe).

How is the car running? Any noticable changes since its gotten worse gas mileage, or is the mileage the only change?

 

[Matt D]

The car is having a couple engine oddities. One, which is probably unrelated, is that the Airbag CEL came on about a month ago. I think that's likely just a loose wire below the passenger seat, where my amp is.

The other oddity has been happening for a while now (6mo+). Basically when I'm coming to a stop from say 2nd gear to a stop light, I'll depress the clutch and the rpms will rev to about 1500 and stay there. I have to pump the clutch and put it in N to get it to drop to the normal idle at 750 or so. It's kind of weird and hard to describe. Sometimes it doesn't completely drop, and it will run high enough that I can let the clutch out in first gear and the idle will accelerate the car (slowly of course).

Now that I think about it, this probably happened around the same time my gas mileage dropped and I just didn't put 2 and 2 together.

 

[Quicksilver]

I don't know Matt, but I think your primary problem is a heavy foot...:>)
When I'm being challenged by large-tired engine modified 4x4 trucks at each stoplight, I end up with poor gas mileage too, anywhere from 12-15 mpg. I have a 4EAT, and don't have the engine idle problem you have. But for 99% city traffic, winter road conditions, with an FXT, your mileage may not be outside of the norm! I'll bet a sixpack of beer that you don't have a boost guage, and can only guess at when you're under boost (and BS to the 'seat of the pants' guage!). Get a boost guage, and pay attention to it, and I'll guarantee that your mileage will improve...if you want it too.
-Quick

 

[xtraag]

I am experiencing the same issue, our 04 FXT has 66k on it and has recently dropped MPG. 6 months ago we had the recommended service, plugs and all that (was $400). Can't think of anything, same tires for the past three years and the only thing added was the front skid plate. Any ideas? Any suggestions on which boost gauge to get? Thanks!

 

[Ryan]

My wife has been having the same issue in her 04 FXT 4EAT. It does have a catless downpipe and a tune. She gets about 15-16mpg. This is her first turbo, so that may be the cause. I drove it highway for half a tank and came up with about 150 miles to that half tank; pretty close to 20mpg highway. Of course she finished it in about another 60 :lol: I know I have a sticking rear caliper piston which may cause some drag. Tires are fairly new. By the time I get that caliper replaced we may have been switched over to summer gas. I agree with one of the previous posts - if you have a boost gauge you learn to drive more efficiently. I used to own a WRX with a boost gauge. I maxed out at 24.5mpg one tank on 15psi.

Ryan