grrr bad gas mileage....any ideas???

[deftsound]

for some odd reason im getting bad mileage, im pretty sure its something wrong with the vacuum lines, lately ive been getting around 125 miles to the tank around town and my stang is almost completely stock, just replaced the fuel filter, intake gaskets, 02 sensor, tps sensor, cleaned intake and replaced a bunch of vacuum line and bypass tubing and i just dont know what else to check besides the vacuum lines, it runs fine, idles a little high i guess if anything, but i cant hear any vacuum leaks or anything...anyone have any ideas?

 

[1986LX2002]

man dont feel too bad i have an 86gt bone stock 5.0 with the factory 2:73's and i'm only getting about 133 miles to the tank. The damn car is a gas hog for some reason. I've replaced pretty much everything just as you. I used to get about 250 to a tank but for some reason its really dropped within the last 3 months . And its not my driving habits either i'm nice to my car "except on the weekends"

 

[deftsound]

yea mine was the same way, before i replaced the intake gaskets stuff was fine, now i got bad mileage, i think its vacuum hose... Between this and the damn interior leak its making me mad, i go to school in galveston texas and it rains every other day and my brand new carpet is getting ruined....i think its the windshield though, i hope...last thing i need is to find out its the body seam or something

 

[jrichker]

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.dalidesign.com/hbook/eectest.html for more descriptive help
OR
See http://www.mustangworks.com/articles/electronics/eec-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.

 

[91StangLX]

for some odd reason im getting bad mileage, im pretty sure its something wrong with the vacuum lines, lately ive been getting around 125 miles to the tank around town and my stang is almost completely stock, just replaced the fuel filter, intake gaskets, 02 sensor, tps sensor, cleaned intake and replaced a bunch of vacuum line and bypass tubing and i just dont know what else to check besides the vacuum lines, it runs fine, idles a little high i guess if anything, but i cant hear any vacuum leaks or anything...anyone have any ideas?

I had the same problem I was only getting about 150 miles to the tank. I did everything and I mean everythingn I could to fix it. Nothing worked until I finally tore the engine apart to replace the rings because it was smoking some. After I replaced the rings and reassembled the engine. The smoking problem went away and my mileage jumped to about 220 in the city and 280 on the highway.

Never thyought a set of rings could make so much difference.

 

[Sevan]

it could be the led foot boys

 

[HISSIN50]

it could be the led foot boys

i would agree (about the lead foot).

a stockish motor should have 15-20" of vac at idle.

do pull codes.

also might want to check the ECT sensor - it can be out of calibration (not toss a code), but be giving incorrect data for the situation (telling the puter your motor is cold when it is warm. result is a rich mixture).

good luck.

 

[FiveO]

i think my problem is the lead foot...after losing torque due to the exhaust mods i tend to shift higher cause thats where all the power went

 

[PhLoBuS]

underdrive pulleys actually help gas mileage

 

[cevtv]

The smoking problem went away and my mileage jumped to about 220 in the city and 280 on the highway.

I just got 280 today - and I still have just under a 1/4 tank left!

 

[04sleeper]

I had that problem once in one of my older cars. It turned out to be a bad fuel pressure regulator. Replaced it with another stock one and mileage went right back up.

 

[deftsound]

hey thanks guys ill try this stuff, if nothing else ill just have the guys at ford dealership figure it out...