1993 Mustang GT Convertible, Only Getting 10 MPG? - Ford Mustang Forum

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post #1 of 4 (permalink) Old 02-02-2009 Thread Starter
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1993 Mustang GT Convertible, Only Getting 10 MPG?

I have a 93 gt convertible and i was wonderong why it gets 10 miles to the gallon it has an bbk cold air intake kit and flowmasters with headers the rest is stock any help thanks

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post #2 of 4 (permalink) Old 02-02-2009
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sounds like it needs a complete tune up.....

Last edited by RLG34750; 02-02-2009 at 03:55 PM.
post #3 of 4 (permalink) Old 02-02-2009
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That's hard to troubleshoot from long distance. A bad or dirty EGR valve will pour soot into your intake, and the computer will adjust your air/fuel ratio to keep the engine running. It would be like running a carburetor with the choke on, little air, maximum fuel. That's one of many possibilities for you to check.

Also, old cars like ours eventually need new Oxygen sensors. If yours are bad, you'd most likely get a check engine light, but then again, it's an old car. The O2 sensors tell the computer exactly how much fuel to add to the incoming air to keep the air/fuel ratio within a specified range. Unfortunately, you can't really test or clean your O2 sensors without risking damage. It's better to just replace them.

Another unlikely possibility, if you've drastically changed your rear end gearing and not changed your speedometer gear to match, your speedometer/odometer will be way off, giving you very false readings, making it impossible to verify your mileage.

For reference, my 325 horsepower 92' 5.0 convertible is super dependable, and I hardly remember to change the oil in her. She still gets 21 MPG city/hwy mix and 27 MPG on the hwy only with 2.73:1 rear end gears.
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post #4 of 4 (permalink) Old 02-02-2009
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I get about 16.5 MPG and I have about the same setup. K&N filter kit, BBK full length headers, 2 chamber flowmasters. I'm not too upset with 16-17 since I don't drive mine every day. But I'd like to see that 20MPG that other people talk about.
It could be a number of things though...
Do you have the stock rear end gears?
When did you give it a full tune up, including fuel filter?
Have you ever changed your O2 sensors?

*****A big question here... Do you run the 10% ethanol gas?
That 10% mix that a lot of gas stations use anymore will KILL your gas mileage and destroy fuel lines and clog injectors and fuel filters.

-1994 Mustang GT "The Red Baron": 3.73 gears,K&N filter,GT40 tubular intake,BBK Full Length Headers,modified midpipe & Flowmaster muffs, timing at 12*. Best time- 14.74 @ 93.16
-Check profile for pics of our car collection!
- AmericanMuscle ROCKS!!
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