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- Cadillac Deville (https://www.cadillacforum.com/forum/cadillac-deville-15/)

- - Bad Gas Milegae (https://www.cadillacforum.com/forum/cadillac-deville-15/bad-gas-milegae-7532/)

when i first bought my 95 cadillac sedan deville i used to get 25 mpg's that was 3 yrs ago. its broken down on me a couple times to many for me. right now im getting about 8-14 mpg. i take real good care of it. i change the oil every 3 months i just did a tune up plugs, wires, fuel filter, air filter, pcv. ive put new starter a couple times cuz they would keep giving me bad mpg also. i always have my tires about 35 psi or 42. my tps was bad i just changed that a month ago but i'm still getting bad mileage.
any help anyone plz. and thankz for the help

RE: Bad Gas Milegae

i have the same prob like you..... bad mileage...... i hope someone can help.

RE: Bad Gas Milegae

Quote:

ORIGINAL: santanerox3

when i first bought my 95 cadillac sedan deville i used to get 25 mpg's that was 3 yrs ago. its broken down on me a couple times to many for me. right now im getting about 8-14 mpg. i take real good care of it. i change the oil every 3 months i just did a tune up plugs, wires, fuel filter, air filter, pcv. ive put new starter a couple times cuz they would keep giving me bad mpg also. i always have my tires about 35 psi or 42. my tps was bad i just changed that a month ago but i'm still getting bad mileage.
any help anyone plz. and thankz for the help

How could the starter give you bad mileage? Starts the car, that's it . . . right?

RE: Bad Gas Milegae

Quote:

ORIGINAL: Tarrance

Quote:

How could the starter give you bad mileage? Starts the car, that's it . . . right?

well the wires were loose on the starter and i didnt know everytime i would start it it would take a while to start. the wires caused that bold on the back of the starter where the wires connect to loosen up. the starter finally went out. this was while i was on a road trip before the starter went bad i was getting 12 mpg after i replaced it it started giving me like 16 mpg.
thats what i thought to the same as u

RE: Bad Gas Milegae

Wow thats interesting. I wonder if its really related or just coincidence. Something to think about though. Thanks

RE: Bad Gas Milegae

imo... a starter would have NOTHING to do with poor gas mileage...... its just a cawinkeedink! something else has changed in your car, or your driving habits.... diff gas,octain, weather being colder, etc.,etc
rickyd

RE: Bad Gas Milegae

Quote:

ORIGINAL: rickyd

imo... a starter would have NOTHING to do with poor gas mileage...... its just a cawinkeedink! something else has changed in your car, or your driving habits.... diff gas,octain, weather being colder, etc.,etc
rickyd

who knows i've always put 89 in gas. i never step on the accelerator i bought my cady just to cruise not to race. idk if its the weather because its been giving me bad gas mileage for over a year already

RE: Bad Gas Milegae

What year is your Caddy?

RE: Bad Gas Milegae

Engine designed for 91+ octane not 89. Timing likely retarded to deal with incorrect fuel and/or spark knock. EGR ports being restricted by carbon is common, throttle body has to come off to clear the ports. Retarded timing will reduce mpg.s

RE: Bad Gas Milegae

you say you never step on the accelerator, maybe that's why. The Northstar is a high performance engine, it has been designed and tested to handle high rpm and hard acceleration. If you never get the engine over 2000 rpm, it can carbon up and that would certainly cause you to have poor gas mileage, because it's choked up. Opening the engine up isn't racing, nor is it hard on it. It truly likes it.

running regular gas on an engine designed to run on premium can cause more problems than just lower gas mileage. People get away with it, but it's a very bad idea.