holy crap i need help Gas mileage horrible

[2.3stangmobber]

ok everywhere i read online it says my car is suppose to give me combines 22 mpg and this thing is only giving me around 18 mpg...ill fill up the tank and 220 miles later its already empty...im like wtf is going on so can anyone help me out and by the way i have done everything you can possible imagine to this thing such as the following....
plugs, wires, fuel filter, fuel pump strainer, i use royal purple 5w-30, change the oil filter with a K&N, changed the diff fluid with royal purple 75w-90, air filter and i cant think of wat else and i have dumped fuel injector cleaners so im like man what am i doing wrong !!!!!!!!...so some one help me out and give me something to work with...thanks you guys..

 

[P-Zero]

What type of gas are you using? If your using premium that could actually hinder your gas mileage if your motor has relatively low compression. Premium fuel is more difficult to ignite. It needs to be compressed more. Thats why you need higher octane for higher compression motors, it resists detonation (ignition due ot compression). Lower octane gas ignites easier thats why its used with relatively low compression engines.

On the other hand, you could have a gas leak.... Also, when you did your tune up did you use Motorcraft parts? Non OE parts are NOT the same, even though they say they are. Either use autolite or motorcraft plugs and motorcraft wires for best results. Since you didnt mention the year of your car, does it have a cap and rotor? And if so, did you change them? A hairline crack in the cap can cause arcing to other cylinders and cause poor fuel economy. Getting any check engine lights?
-P.

 

[dreamer1uk]

Hi,

When was the last time your o2 sensor was changed? Also a faulty ECT sendor can cause the engine to dump more fuel in the cylinders.

Id look at the o2 sensor next.

I use 92 octane gas for the detergents in that gasoline as well as the octane level. Higher the octane, the more of a controlled burn it has. Some people may say its overkill on a N/A motor but i use it on all my cars and have noticed an increase in MPG.

 

[2.3stangmobber]

im sorry how stupid of me its a 93 dis less system. and i did use motorcraft plugs and the wireset i used bosch i already changed everything on the car...name it and ive done it.....including the o2 sensor and no check engine lights....only sometimes when i drive the tach ometer goes down from 3000 to 1500 and i used a scanner and it was code 553 or something like that talkin about one of the modules so i guess i need to change em....but i changed everything...its making me really mad... so idk anything else guys ? and i use 93 octane and sometimes 87 so idk....

 

[stykthyn]

no need for 93. run 87 and you will be fine. how many miles are on your car and what kind of driving performance do you have? is it getting tired? maybe a compression test may be in order? also a vacuum leak will drop your gas mileage. a vacuum check should read 20 inches or so at idle.

 

[2.3stangmobber]

ok so today i checked the oil on the car and it was saying that the oil was way over full... but im thinking to my self that i only added 4.5 quarts last time i changed the oil so it shouldnt be this high...and i know that if theres too much oil that could **** up my gas mileage....could the K&N oil filter be doing something to the oil reading ? i dont think so but a second opinion wouldnt hurt thanks guys...

 

[svobrad]

Check this

On my 1986 SVO the mechanic said a bad coolant sensor code is resulting in the engine using more gas than it should.
Seems the engine thinks it's still cold thus it dumps more gas in than normal.
Sensor located on the lower intake manifold.
A lot easier to get to if upper intake is removed.
Have not had a chance to do this yet.

 

[bonestock87]

Have you changed your thermostat lately? Same prinicpal as svobrad mentioned. If the thermostat isn't opening, your gas mileage will suffer.

 

[Mustang928]

Where is the thermostat on these cars?

 

[bonestock87]

Follow the upper radiator hose down to the motor. Remove the hose, remove the heater hose, then unbolt the flange (2 7/16 bolts). It's inside that flange/collector thingy. Be sure you notice how it is installed so you can install a new one the same way.

 

[blue71mustang]

I just changed my engine coolant temp sensor and thermostat and I picked up 4mpg avg. I did have a code fault for engine coolant temp sensor.

I was going to start this exact same thread the day you posted yours. I wasn't down to 18, but I was at 21 combined when I was used to 25 combined.