- Jan 7, 2012
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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).
Fuel Economy 1994 GT
- Thread starter Widmerdude1
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79'293stang
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My HCI Supercharged 94 GT gets 22mpg Highway. So if you are below that its time for a major tune up.
Three50won
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- Jul 11, 2010
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Widmerdude1, what do you consider to be horrible gas mileage? How much are you getting? Whats been done to the car?
- Jan 7, 2012
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Three50won
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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...
- Jan 7, 2012
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So i was wondering, can O2 sensors cause this? I just hate taking cars to the shop, but if i have to...
Three50won
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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
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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...
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
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.
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
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Skymarshal
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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.
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.
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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.
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