Hello. I just went 64 miles on almost a quarter of a tank. I thought that was real odd so I filled it up, and calculated 14MPG. It is ridiculous; I usually get 20-22MPG. I do not know what is wrong. I used the same gas I always use. I put fuel injector cleaner in 3 weeks ago. No CEL. What could be the problem? I changed the fuel filter a year ago, 10,000 miles. Oil change not even 1,000 miles ago. Does anyone have a clue. I am thinking it may be the knock sensor, maybe? I need some help.

 

The gas gauge is not accurate.

 

Yes. Mine fluctuates a lot. The thing is I bought 4.5 gals of gas after traveling 64 miles. That turns out to be: 14.2 MPG which is no where near it needs to be. Meaning something is wrong with my car.

 

could be ur injector cleaner....
i know FP60 and LC20 reduce ur gas mileage horribly for the first two tanks until it cleans all that it has to.

 

I used Chevron from Walmart. It is in a black bottle. Forgot exactly what it was called. The bottle is in my car though. I'll take a look at it and see what it is.

 

I’m confused. You had a ¼ tank, used it in 64 mi, filled it to what you thought was another ¼ tank, and calculated from there?

If that is indeed the case, everyone is correct, the gauge is merely an indicator/reminder. (Qualitative vs Quantitative)

 

I didn't know I was confusing people. Here is what happened. I filled up a full tank of gas Monday. Went 64 miles in 3 days. The tank was down 1/4; 3/4 full. I filled up with 4.5 gallons of gas, topping off the tank. And got 14 MPG. Hope this clears it up. Now I need to know what is wrong, if anything. I'll check what cleaner I got.

 

maybe you were real heavy on the foot for a few days. i wouldnt worry about it until you notice this happening for awhile. probly just some random thing and itll be back to normal. (assuming your car is fine and didnt throw any codes)

 

Ahh, I see now. I've done the same and have obtained anomalous results as well. I think the best way is to calculate only after a full tank so that it represents various types of driving habits.

 

Maybe this will help? http://forums.maxima.org/showthread.php?t=539969

 

By 'topping off the tank' do you mean continuing to fill it after the pump clicks off? That will skew your results.



...please god, not another mileage thread...

 

Each pump will top off at a different level. IME this can be as much as a gallon difference.

But a couple months ago I managed to get 15mpg for most of tank which seemed really bizarre. But then it was normal (25mpg) on the next tank. Perhaps the gas was bad and tripping the knock sensor, I dunno but if mileage is the same for a few tanks in a row you know you have a problem.

Dave

 

my gas gauge won't move below the fill line until after 100 miles. The top quarter of the tank gives be about another 100 miles with each successive quarter giving me different mile-age. The only real way to tell is drive your tank till empty, fill it up completely and then drive it to empty again and recalculate.

Check your tire pressure as well.

 

Tough to say, I know I usually go about 115-130 miles before I hit the 3/4 line, but I wouldn't totally trust it.

 

all pumps fill to a different point.. if u want real results u have to fill almost till spilling...not recommended.. but thats the way u can do it get the best and most accurate result.

 

Or average out over several consecutive tanks.

 

There is a more accurate way!!

Wait till the gas light comes on steady on a flat surface, immediatly hit the trip button, when you fill up add exactly 10 gallons (makes the math easier) than, next time the light comes on steady again, look at the trip. 243 miles= 24.3 mpg. It's not only easier, but it's more accurate for several reasons..........

 

keep watching it man,..........yes 14 is really bad,but unless u have codes, i think u shud be good,maybe jus some random thing as someone already said.

 

Of course, that's assuming that 1. the low fuel light actually works, and 2. it comes on at the same point every time. More than likely it's not accurate to within the gallon as nothing critical depends on it, it's merely an information output for the driver.

 

Fill up, hit the trip botton to zero...drive till 1/4 tank is left, fill up again and devide how many miles you paid for, into the gross mileage you drove on the trip clock (13.4/340)

Thats the right way to do it !! Discussion Over.

-matt

 

you need a more accurate system my friend. this is what i do:

start with a full tank. then set odometer to 0
next trip to gas station fill it up (pay with a card).
write down miles traveled on receipt and reset odometer
when you get home you know how many miles you went for whatever GAL on the receipt

 

lol you sound like Mario Andretti on that Firestone commercial

 

i had the same exact problem and it was my O2 sensors in the back and my solenoid. but after they fixed it i got good gas millage im getting like 23 - 24

 

Thats just bad advice.

 

Enlighten me how that is more accurate ??

Its not that hard kids. Fill up, reset, drive till 1/4 tank is left, and do some math after you fill up.

-matt

 

The short answer: A 1/4 tank of gas and 64 miles is not enough to conclude anything. Run a few tanks of gas through and then see.

P.S. Don't run your car till the light comes on, that's not good for an older car.

 

stop driving with your foot on the floor! or ... stop shifting at 7 grand every time! lol sounds like you could possibly have a bad FPR ... or really really dirty injectors. You can pull the injectors to really clean them if you get ****, but typically a take of high octane and some cleaner makes it good to go.

 

is it easy to remove injectors to clean?

 

Front three are easy, but the rear will involve the upper intake manifold being pulled off.

My guess would be bad O2 sensors

-matt

 

are you pulling any codes at all ???? Good call Matt on the o2 sensor. I wouldn't do the injectors unless you really needed to. Like Matt said, till be a beotch of a job to do the rear bank. But .. while ya got that intake off, get a MEVI or 00vi FTW!!!!!

 

Actually, it's not. I've never done it but it should work pretty well. It's certainly far better than the 1/4 tank crap.

Dave

 

64 miles in three days... Lets see how many short trips you made during those days? How many times you left the car running for whatever reason? Did you warm up the car before driving it? How's your driving style? Like others said, 1/4 tank of gas doesn't provide enough data

 

Actually for your knowledge, warming up the car wastes gasoline

In the summer 30 seconds is MAX thats needed on a cold start, in the winter 60 to 90 seconds is all that is needed

All you have to do is drive slowly until the car BEGINS to heat up, meaning not let the rev gauge past the 3000 rpm mark

 

Yes, I know that warming up the engine uses gas -that's why I asked him

 

HAhahhaa lol ooopsie i made a pooopsie

sorry my 17.5% wine is affecting my mind, carry on hahaha

 

Acually, it is. Have you ever had the tank off of a 10 year old car to see the crap that's in the bottom of it? Be nice to you fuel system and don't run it below a 1/4 tank.

I not sure what " 1/4 tank crap " your referring to.

He obviously knows how to calculate his mileage based on his statement.

All I am saying is not to panic and start throwing parts at a problem that might not exist. keep a tab on your mileage and if it continues to be low, than yes there is a problem.

 

i get the same mileage 14MPG WTF

 

I've had the tank off of a '73 Duster, three different old Trans Ams, a '90's church bus, an '83 914, and a number of other random cars. Never more then a few pinches of debris in the bottom of the tank, so I don't know what everyone is all about 'debris will be sucked into your fuel system' and such.

 

^^^ Ultimately, it's your car. You do what's best for you.

 

Actually I changed a gas tank last night. Have you forgotten that the fuel pickup is always at the BOTTOM of the tank? If there is crap in the tank you'll pump it whether it's full or at 1/8th. Running a tank closer to full doesn't do a damn thing.

Dave