WTF does my gas mileage suck so much?

[Nvidia]

Mods are in sig.

Right now, I'm getting about 8 MPG, or about 60 miles to half a tank before I get the gas light back on again.

I did plugs and wires, but this is what I'm figuring I can still try.

- Oxygen sensors
- Gas Cap (Mine feels really loose and I read a little while ago in a newspaper that gas mileage can be affected as much as 15% per month by a non-sealing gas-cap)
- A tune from a chip burner or something

Anyone think it might just to be tuned to get some back? It runs like a pig, even with the cats on (you can still smell gasoline pretty good with em on, and with em off, you smell it so bad you would think the car has dumps)

Thanks :SNSign:

 

[302RollinHard]

possible O2's pull codes and see what it says.

 

[jrichker]

The things that it takes to pass emissions testing are the same things needed for good fuel economy.

1.) Make sure all the emissions gear the car was made with is present and connected up properly. That includes a working smog pump and cats.

2.) Make sure that you have fresh tune up with spark plugs, plug wires, cap, rotor, fuel & air filters. An oil & filter change is a good idea while you are at it.

3.) Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/article...c-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.

Or for a nicer scanner see http://www.midwayautosupply.com/det...iption.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $33.

4.) Post the codes and get help to fix them. Clearing the computer just temporarily removes them from memory, it doesn’t fix the problem that caused the code to be set.

 

[dragnazz5.0]

what did the plugs look like? could it be bad injectors? or maybe just one bad injector. i had a bad injector and replaced it and my gas mileage went from 15mpg to 20mpg in 15 minutes and the car runs 100 times better than it did before

 

[Walternator]

what did the plugs look like? could it be bad injectors? or maybe just one bad injector. i had a bad injector and replaced it and my gas mileage went from 15mpg to 20mpg in 15 minutes and the car runs 100 times better than it did before

How did you determine that you had a bad injector?