dramatic decrease in gas mileage

[sreilly77]

just recently i have notice on my 95 town car that the gas mileage is horrible. it used to be an excellent 15 mpg city with the 191,000 miles it has on it. now after calculating it, it has dropped to 8 mpg city . i can't figure out whats the matter with it. all the maintenance is up to date. there is not carbon build up, no CEL, no leaks or anything. it runs really smooth. any input would be helpful.

[Towncar]

Originally Posted by sreilly77

... any input would be helpful.

Well, you did say any input...

- someone is stealing your gas right out of the tank. I once played a joke on the wife, adding several gallons over time while she was doing her calculations she proceeded to tell everyone she knew how she was getting over 60mpg in her Jeep Cherokee 6cyl

- your calculator is'nt working properly.
- your gas station isn't telling the truth on the amount pumped.
- your odometer is reading way off. (fewer miles than actual)

It seems to me mechanical / electrical problem should be throwing codes. I know you keep your TC filters and such in great shape.

that's my

After reading some other responses to the same problem, well not exactly the same, his 1991 went from 20 to 15mpg..
The replies were:
- "If the (ETC) Engine Coolant Temperature sensor does not read correctly, you will not get the milage you're looking for"
- "Have you considered swapping out your TPS sensor? I've had the best results to date with "Borg-Warner" replacements (Pep-Boys). I had them go bad at 5K miles intervals causing poor mileage, strange idle, pinging, and other strange driveability issues. 4K miles on the Borg-Warner without problems. As a side note; once replaced (and PCM reset) the mileage increases by 3 to 5 MPG immediately"
- "I would disconnect the negative battery cable for five minutes and then reconnect. Start the car and let it idle about five minutes before driving. You should notice a increase then." "this clears the KAM and resets the fuel trims back to normal or relearn/base strategy"

[sreilly77]

Originally Posted by Towncar

Well, you did say any input...

- someone is stealing your gas right out of the tank. I once played a joke on the wife, adding several gallons over time while she was doing her calculations she proceeded to tell everyone she knew how she was getting over 60mpg in her Jeep Cherokee 6cyl

- your calculator is'nt working properly.
- your gas station isn't telling the truth on the amount pumped.
- your odometer is reading way off. (fewer miles than actual)

It seems to me mechanical / electrical problem should be throwing codes. I know you keep your TC filters and such in great shape.

that's my

After reading some other responses to the same problem, well not exactly the same, his 1991 went from 20 to 15mpg..
The replies were:
- "If the (ETC) Engine Coolant Temperature sensor does not read correctly, you will not get the milage you're looking for"
- "Have you considered swapping out your TPS sensor? I've had the best results to date with "Borg-Warner" replacements (Pep-Boys). I had them go bad at 5K miles intervals causing poor mileage, strange idle, pinging, and other strange driveability issues. 4K miles on the Borg-Warner without problems. As a side note; once replaced (and PCM reset) the mileage increases by 3 to 5 MPG immediately"
- "I would disconnect the negative battery cable for five minutes and then reconnect. Start the car and let it idle about five minutes before driving. You should notice a increase then." "this clears the KAM and resets the fuel trims back to normal or relearn/base strategy"

you know come to think of it, i did fill the car the other day at a different gas station than the one i usually fill up at. i usually put Shell gas in my car and that gives it the awesome gas mileage, but last time i put Hess gas in it because it was on my way home one day. now i replaced the TPS sensor probably within the past year or so. the K&N air filter was put in at the beginning of summer so thats fine. oil was changed back in the beginning of july with a K&N oil filter and the gas mileage jumped then. and i did the fuel pump and fuel filter back in march according to my records. hmmm. i think next time i am going to go from mid-grade gas to premium and put in some gas treatment and injector cleaner and see if that works. now i know i have a 19 gallon gas tank and i always fill it up all the way. the next time it gets down to 4 gallons i'm going to keep an eye on the meter on the pump so i know that i am gettin around 15 gallons of gas...instead of taking my work truck to work ill use my town car so it burns the gas and then fill it. i filled it last thursday so i guess by either tuesday wednesday or thursday of this week ill fill it. so ill update you then.