Fuel Economy 1994 GT

Widmerdude1 · Jan 7, 2012

I am getting horrible gas mileage, just bought this and havent taken it to the shop yet, thought I would rack all your knowledge before I do. Was hoping it was a easy fix(ya right).

79'293stang · Jan 7, 2012

My HCI Supercharged 94 GT gets 22mpg Highway. So if you are below that its time for a major tune up.

Three50won · Jan 7, 2012

Widmerdude1, what do you consider to be horrible gas mileage? How much are you getting? Whats been done to the car?

Widmerdude1 · Jan 7, 2012

Three50won said:
Widmerdude1, what do you consider to be horrible gas mileage? How much are you getting? Whats been done to the car?

completly stock, and about 10 to 15 mpg, maybe a little more one the freeway

Three50won · Jan 7, 2012

Yea that seems a bit low, although it was advertised at around 17-20 city and 25-30 hwy. You gotta factor in age, mileage, driving style, etc...

Widmerdude1 · Jan 7, 2012

Three50won said:
Yea that seems a bit low, although it was advertised at around 17-20 city and 25-30 hwy. You gotta factor in age, mileage, driving style, etc...

So i was wondering, can O2 sensors cause this? I just hate taking cars to the shop, but if i have to...

Three50won · Jan 7, 2012

It is possible if the sensors are worn or not operating properly. You don't need a shop to replace them tho, you can do it yourself, it's easy. While you're at it, do a tune up, get a K&N air filter, clean the MAF sensor with MAF cleaner, and check all your vacuum lines...

Widmerdude1 · Jan 7, 2012

Three50won said:
It is possible if the sensors are worn or not operating properly. You don't need a shop to replace them tho, you can do it yourself, it's easy. While you're at it, do a tune up, get a K&N air filter, clean the MAF sensor with MAF cleaner, and check all your vacuum lines...

ok and is there a way to test the O2's to see if they are bad? just so i know they are dead.

Three50won · Jan 7, 2012

That my friend is a question I can't help out with outside of saying to check for codes...maybe there is a way to do a voltage check but I wouldn't know what voltage to look for. Somebody else will have to chime in...or do a google search. I'll look around and see if I can come up with more info for you...

Bullitt347 · Jan 8, 2012

The right scan tool can check for bad 02 sensors. Just because you may have an 02 sensor code does not mean the sensor is bad. The code can be set because the sensor is reading exhaust gases outside the accepted range, so the sensor can be working perfectly fine but sending a code that something is wrong. With a scan tool that can PID monitor the sensors, you can look at the switch rates of the sensors to see if they are working properly. The rear (after cat) sensors should switch at a much slower rate than the front sensors. Usually if the rear sensors are not switching, or are switching at the same rate as the front, then the catalytic converter may be bad. There are at least a dozen things that can make a 02 sensor code appear and none of them can be fixed by replacing the 02 sensor. Fix the cause, not the symptom

Mustang5L5 · Jan 10, 2012

1994 is still OBD1. Unsure if it has that capability to monitor the sensors in the way OBD2 can.

Starting point would be to run your check engine codes and give the car a full tune-up. You should be able to manage at least 20MPG or more on the highway, no matter your mods.

How are you calculating fuel economy anyway? Sounds like you are just estimating rather than filling the tank, recording the number of gallons and miles driven and doing some math. If your speedo has been corrected due to aftermarket gears, or if your tire size is non-stock, your numbers could be bit off.

SlammedGT · Jan 10, 2012

I get a pretty steady 23 no matter how I drive... are you sure you are calculating it right?

Skymarshal · Jan 11, 2012

O2 sensors can fail without triggering a code. It's good practice to replace them at 100k anyway. I don't know about the '94, but later models have four sensors but you only need to replace the front ones. I got them for $20 each from Rock Auto.

10 MPG might almost suggest a mixture problem or fuel leak. Any fuel odor around the car? Maybe get under it with the pump running and look for leaks. Pull a spark plug and see if it's black and sooty from too rich a mixture.

Widmerdude1 · Jan 11, 2012

SlammedGT said:
I get a pretty steady 23 no matter how I drive... are you sure you are calculating it right?

Yes, The tank is filled, trip gauge reset, filled again mileage / gals

Bullitt347 · Jan 13, 2012

Mustang5L5 said:
1994 is still OBD1. Unsure if it has that capability to monitor the sensors in the way OBD2 can.

.

OBDII has it's own capabilities, OBDI uses different diagnostic tools, and the 02 sensors can be monitored, even without a scan tool if you have a lab scope or even a DVOM. . It is all in knowing how to gather the information from the sensor. The problem is most people want the "Silver Bullet" answer, and most times it does not exist. You still have to do the testing and diagnostics to find the problem. Hell, AutoZone will read the codes for free and sell you parts all day long that will not fix the actual problem. It is very easy to look for the easy way out or easy answer, and sometimes that works, most often it does not. It is amazing how many people cannot afford to fix it right, but can afford to fix it over and over and over again. As in most things in life, the "right" thing to do is never the easy thing to do. My 2 cents on this "diagnostic" concern is that 90% of the time or more, new 02 sensors are not going to fix this concern. Go ahead and spend the $ if you want, but it is not going to help.

Fuel Economy 1994 GT

Widmerdude1

New Member

79'293stang

Active Member

Three50won

Widmerdude1

New Member

Three50won

Widmerdude1

New Member

Three50won

Widmerdude1

New Member

Three50won

Bullitt347

I have been doing it wrong this whole time

Mustang5L5

That is…until I whipped out my Bissell

SlammedGT

Active Member

Skymarshal

Member

Widmerdude1

New Member

Bullitt347

I have been doing it wrong this whole time

Similar threads

Fuel Economy 1994 GT

New Member

Active Member

New Member

New Member

New Member

I have been doing it wrong this whole time

That is…until I whipped out my Bissell

Active Member

Member

New Member

I have been doing it wrong this whole time

Similar threads

Privacy & Transparency

Privacy & Transparency