Shackleford

iTrader: (12)

I usually overestimate 20 mpg mixed. I put like 5.3 gallons in the last trip to the gas station. A rough estimate was 100 miles before I add more gasoline. I basically ran out at 91. I pulled into a parking lot before I was stuck in the middle of the road during rush hour and then had my brother bring me some gas.

Air filter is fine
Plugs and wires are just a few months old
New fuel filter
Ran SeaFoam in the fuel tank within the last six months or so

I suspected my oxygen sensors were going up until recently because the car would bog down a bit right after any start up then hit the gas until I guess the oxygen sensors warmed up. It hasn't done this in awhile, so I never replaced them with some used ones I bought that have much fewer miles than my car has, which is 130K.

Anymore ideas?

conan

iTrader: (5)

Have you pulled a plug or two from each side of the engine to see how its burning?

Black FormulaLs1

iTrader: (10)

tire pressure? what kind of wires are you runing? what kind of plugs and air filter are you running?

Shackleford

iTrader: (12)

Ah. I forgot to mention I have a nail in my passenger rear tire. lol.

samson_420

iTrader: (1)

Alignment can also cause crappier MPG.

bongva

iTrader: (7)

if one of your tires are lower in pressure than the rest... that will also cause shitty mpg

Shackleford

iTrader: (12)

I got a front end alignment just a few months ago.

Shackleford

iTrader: (12)

Yes. I know. I'm hoping that's the culprit. I'll have to get that patched today or tomorrow.

1996firebirdformula

iTrader: (3)

I had Nail in same tire. I put 36 psi in all tires then next day i had 24 and today i had 17. So i found the nail and pluged it. My car isn't dartin on hills now. Probably help gas milage too.

406malibu

the way your "estimating" mpg doesn't work, these gauges aren't accurate. fill it ALL the way up, drive a hundred miles, then fill it to the top again, then divide miles by gallons. estimating will get you nowhere, trust me, ive tried it

Shackleford

iTrader: (12)

Actually, it does work. I don't base it on the needle. I base it on how many gallons I put in.

samson_420

iTrader: (1)

I calculate my MPG the most simple way. Fill it to the top(untill the pump stops on its own). Drive it untill it is only about 1/8th of the tank full. Fill up. Then divide the miles you have put on since your last fill up(I just use the trip) by the gallons you filled up with this time, also untill the pump stops on its own.

twitchtwice

iTrader: (12)

fill tank full. reset trip. when you go to get gas again, calculate the amount of miles put on the car, vs the amount you are about to fill it up with

Weiser878

This happened to me starting a few months ago. I ran out of gas once, figured I miscalculated. Twice, knew something was up.

It was when the 10% ethanol was added to all our local gas. Turns out the Shell where I always got gas held out the longest before switching to E10.
I got about 18-20 less miles on a tank.

And the price went up

SOMbitch

iTrader: (8)

A dirty MAF can cause a gas mileage drop.

Dyosis

iTrader: (3)

Yep, I noticed this too. I get worse gas mileage when I have to run the Ethanol mixed gas. I found a couple of stations around here that still have 100% gas and try to fill up there when I can. It's usually about a 0.20 cents more per gallon, but it is worth it. I can really tell a difference.

Other than that, tire pressure, fuel filter, air filter, spark plugs.....the normal tune up stuff.

Shackleford

iTrader: (12)

It was definitely the tire that had the nail in it that was going flat. lol. I got that fixed Monday. The fuel economy has surely improved.

Also, you mean 0.20 dollars more per gallon? 0.20 cents more per gallon is not a lot. lol.