why is my car wasting more gas than usual?

Question

i have a 2000 mustang gt (v8) two weeks ago my car was giving my 19 mpg like usual and its pretty good for a v8, but about 2 weeks ago ive started to notice that my gas milage was decreasing bad right now im getting 15 mpg and 16 is im lucky, i already check the air filter and its good its only been on for a bout 2k miles and my oil change its not due until about another 1k miles, what else could the problem be, please i need some help because gas is killin me thank you in advance

i already did all the basic check up , filters, oil change etc. this change happened all of the sudden pretty much from one day to the other i went from 19mpg to 15 mpg thats a big change

Answer 1

Unfortunately in the summer or hotter times of year gas mileage goes down due to the inhibiting of the conversion process from liquid to gas due to the molecular expansion of the gasoline from heat. Also, could be increased use of Air conditioning or just plain old expansion of engine parts which helps aid in gas evaporation.

Answer 2

80% sure that the person who said O2 sensor is right on. Low tire pressure would not cause that much drop. Dirty filters would not cause that much drop. Old oil, sorry still wouldn't do it. The key here is that it suddenly started going down in mileage. If it were a normal wear item like a filter that is slowly going bad you wouldn't notice the change all at once, your mileage would just slowly over quite some time be reduced. Since it dropped suddenly you definately have something that isn't opperating correctly. Check the O2 sensor, Fords especially seem to go through them quickly. Even if it's not completely shot yet they can go bad in stages without tripping a check engine light. Even if it's not your O2 sensor you still have a problem with your fuel injection system some where, get the Haynes manual and start working your way through the diagnostic section and you will find the problem. Try to ignore people that tell you to check your tire pressure! :)

Answer 3

More Gas Than Usual

Answer 4

The gasoline suppliers change the additives they add according to government emission mandates during certain times of the year.You probably have a tank full of low vapor emission gas that doesn't burn as well as winter grades.And the air temperature affects the mileage and performance,that's why some people are installing cold air intake systems.

It's interesting to note that quite a few mechanics stated that the a/c harms the gas mileage when other debates here deny that.Who's telling the truth? I'm going with common sense.Yes it is bad for gas consumption.

Answer 5

Try changing your fuel filter first. If that's it I that'll save you some cash. Next try some type of engine cleaner that cleans your entire fuel system. The last thing and most expensive is probably spark plugs. The only other question is how many miles your vehicle has on it. Vehicles eventually lose a little mpg when you get close to 100k any way

Answer 6

O2 sensor.

Symptoms :

* Failing an emissions inspection.
* Excessive fuel consumption.
* Driveability problems, such as engine surging or hesitation.
* The Check Engine or oxygen sensor light appears (on earlier vehicles).
* The on-board computer stores a mixture-related diagnostic trouble code.
* Fouling spark plugs.

Oxygen sensors are not unlimited-life components. It's true that newer designs last longer than their predecessors, which explains why O2 sensor replacement intervals were often included in vehicle maintenance schedules. Today, most vehicle manufacturers have changed that strategy and consider oxygen sensors to be "replace when they fail" components. When (or if) an oxygen sensor fails, there could be several logical reasons why. These include:

* The unit has exceeded its design-life expectancy.
* The vehicle burns too much oil (causing sensor carbon fouling).
* An internal engine antifreeze leak has contaminated the sensor.
* Internal contamination by silicone (used in spray chemicals, gasket material, etc.).
* The sensor has become coated with other residual chemicals.
* External contamination by other automotive chemicals (undercoating solutions, etc.) applied in proximity to the O2 sensor.
* Fueling with contaminated or leaded gas, causing lead fouling.

Sensor Inspection & Testing
The oxygen sensor should be inspected during every engine performance service, or whenever its performance is suspect. A visual inspection alone can't verify the functionality of the oxygen sensor. An oscilloscope test of the sensor's ability to respond to changes in exhaust oxygen content, as well as a measurement of its response time, will provide a more definitive diagnosis.

To test an oxygen sensor's ability to respond to rich and lean conditions, follow these steps:

* Connect the oscilloscope leads to the O2 sensor circuit. For vehicles that use a three- or four-wire heated O2 sensor, you may have to bridge the connector leads and tap into the signal wire with an appropriate test probe at the connector plug.

* Warm the engine to operating temperature (oxygen sensors work properly only when they're hot-at least 350[degrees]F or 600[degrees]C). Run the engine at about 2500 rpm for two or three minutes to heat up the sensor.

* Hold engine speed at a steady, high idle between 1200 and 2000 rpm.

* Artificially drive the system rich (using propane) and lean (by opening the brake booster hose) as you observe the oscilloscope voltage reading. It should peg from .800 to .900 volt (full rich) to .100 to .200 volt (full lean).

Minimum and maximum sensor voltages are just part of the picture. How fast these transitions occur is an equally important measure of O2 sensor health. Lean-to-rich and rich-to-lean transitions should occur in 300mS or less; anything greater may indicate a worn or contaminated sensor. An oscilloscope or graphing multimeter is essential for this test.

A limited number of vehicles are equipped with a new type of oxygen sensor called an air/fuel ratio sensor. Unlike the toggling voltage produced by conventional sensors, the air/fuel ratio sensor produces a linear voltage signal. Testing methods are also different. This type of sensor allows more precise monitoring and correction of the fuel mixture than was possible with conventional O2 sensors, and may receive more widespread use in the future.

Regardless of their performance characteristics, all oxygen sensors are now heated. Heating the sensor gives it a longer design life, in part because it can be placed further downstream in the exhaust system. This protects the sensor from the thermal shocks caused by engine heating and cooling cycles. Heated sensors also reach operating temperature quickly and begin producing a sensing voltage without having to wait for the heat of the exhaust to warm them.

Heated oxygen sensors have smaller slots in the protective tube at the tip. This limits the amount of exhaust that reaches the sensing tube, and limits the contaminants that can reach the sensor and diminish its response. Consequently a heated O2 sensor may last 100,000 miles or more.

Answer 7

You need to take the car to a shop that can scan the computer and look for reading that are out of range. Most everything that i can think of that would cause that kind of loss of fuel mileage should turn on the MIL. The one thing that sticks out though would be if the tranny is not shifting into OD.

Answer 8

you have said whats the problem when you asked your question; your problem is that your car is a Mustang GT! I have a 94 mustang GT, and have noticed that as long as i keep the RPM below 1.5, fuel consumption is reasonable...once i step on the pedal, i know i will be visiting the filling stations soon.
btw, make sure your engine temp. does not go high, and check your exhuast system that it is clear from Carbon blockage!

Answer 9

There could be many reasons you are getting bad gas mileage! One, your air filter may be clogged.Two, you may be running your air conditioner more.Three, you may have a low tire which causes you to use more gas.Four,you just might be driving faster this week then you were in the past couple of months.The faster you drive the more gas you will use.

Answer 10

running the A/C full blast? I loose 1.5 to 2 mpg in the summer. are you doing more stop and go? check your tire pressures. any thing else wrong should show up as a check engine light.