Hello all, I have just recently noticed a sharp drop in the good ol' MPG. In town hasn't changed...about 18-19, according to me, not trip computer. However highway MPG has taken a huge dump. Used to get 27-31 on highway depending on wind. Lately though, I am getting 22 - 24 MPG going 78, consistently (three tanks) with no wind at all...I also have an automatic.

 

sounds right to me.....
never remember getting 27-31

 

hmm, well I never remember gettings 22-24 on highway. I was getting l ike 26-27 with stock air filter, then once i got the K & N it went up to where i said.

 

Crap gasoline?
Air filter needs to be cleaned?
Tires improperly inflated?
Extra weight in car?

 

BP (Amoco) Ultimate 92 octane
Just cleaned K & N Drop In
Tires are inflated
No extra weight in car

On a side note, all this pretty much started after I made the horrible mistake of running a whole tank of 93 Octane with ethanol through my baby...

 

If you started using E10 gasoline (10% ethanol) then that could be the reason. Back in April of this year when it became mandatory that all service stations in Hawaii sell E10 gasoline, I noticed a slight drop in mileage and performance. As of now, the car feels fine. You'll just have to get use to it.

 

Gas mileage thread count: 594,203,044.

 

This one is a bit different tho. He is asking why there would be a drop, not what everyone is getting.

 

I have never seen over 24.xx in my 4AT 3.5L.

And that's going 75-82, averaging 77 mph for 630 miles.

 

I NEVER NEVER EVER use ethanol. It makes my car smell like crap, and the mileage goes wayyy down.......like 10-11 in town. And I don't believe that we can run our cars on E10 anyways. Anyone know of any good fuel system cleaners?

 

You CAN run on up to 10% ethanol w/o problems other than decreased fuel economy. Read your owners manual. E10 has been very common in the midwest for some time. It'll soon be everywhere now that it's federally mandated. Your milage decrease is most likely fuel related. Pumps are not always labelled.

 

They just started dumping ethanol gas on the market not so long ago, none of any scientific proof that ethanol won't harm the car in real life just to what extent. Ethanol is a complete scam IMO.

 

Go get the Chevron Techron concentrate. Good stuff.

 

Not to offend anyone here, but I can read..all the pumps I use are labeled, and none of the gas i have put in has ethanol in it.

 

bull crap. i read on all, it says may contain up to 10% of something... ethanol, sufur or something of that ordeal.

 

O2 sensor.

 

the more you know

http://www.ethanol.org/e10.html

 

Makes perfect sense. Since city highway wasn't affected.

Since the engine is not under much load on the highway, readings from the o2 sensors are used for A/F adjustments.



Whereas when in the city, MAF is more likely being used as feedback for A/F control, so in regards to your concern, city driving will not be affected by a bad primary o2, but highway mileage will be.

 

check it manually at each tank just to make sure you are getting an acurrate reading. mine was off by a few when i did my own manual calculation

 

could also be the mix used for winter gas

 

IDK, I am currently in Omaha, NE and I doubt they use winter blends of gas. I know in ND here they do. I added some fuel injector cleaner in my tank of gas today, we will see if that helps at all. If not, maybe dirty fuel filter. I know they are supposed to never need changing.....BUT...

 

What about your o2 sensor?
what about your o2 sensor?
What about your o2 sensor?

 

If you justed cleaned the K&N, and now you have a problem, it is always possilbe that you may have used too much oil and the oil is all over the MAF wire. Look inside the intake tube and see if any oil is past the filter.

 

Nmex - any way to test and see if its the o2 sensor?? Shouldn't I be gettin th SES light?
Sascuderi - The problem existed before I cleaned the K&N. Its the whole reason I cleaned the K&N.

 

It could be a slowly dying sensor. I still do not undrstand how you got anything over 24 at that speed, since mine has never seen that good of mileage.


Also do not think it's the MAF :read my earlier post:

 

Ya I don't either...I have a 2002 made in 02/06. Also its the supposed stronger AM600 MAF

 

let us know if the fuel injector cleaner works. thats a good idea especially if a car has been subjected to ethanol!

 

well im in maryland, and i know THEY DONT USE ETHANOL........but OUR pumps are not labeled

 

Most VA pumps contains ethanol. Consider MD is bordering VA...So where do you think the MD gas come from?

 

NOT FROM VA

 

A good fuel system cleaner and one of the strongest solvents available to the general public on the market is...

Gasoline

 

Alrighty, looks like the generic fuel injector cleaner I put in did the trick. Now I'm getting the mileage I should 27-28. Thanks guys!