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Discussion Starter #1
Hi, I'm a newbie so forgive me! But I've had my 93 STS for about five years now and it's always gotten what I thought was pretty poor mileage. It's about 9-11mpg city. I checked it out manually starting with a full tank so I wasn't just relying on the on-board computer.

I tried talking to the shop at the local dealer here about it, but they sortof shrugged me off and said that mileage wasn't so bad and they didn't think there was anything wrong.

On the other hand, I've read about people getting much better mileage than this. I've had the problem not just in LA's awful traffic, but in rural Florida it wasn't much better. Am I nuts or is there potentially a problem I can get serviced?

Thanks for your advice!

--Joe
 

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jzapert said:
Hi, I'm a newbie so forgive me! But I've had my 93 STS for about five years now and it's always gotten what I thought was pretty poor mileage. It's about 9-11mpg city. I checked it out manually starting with a full tank so I wasn't just relying on the on-board computer.

I tried talking to the shop at the local dealer here about it, but they sortof shrugged me off and said that mileage wasn't so bad and they didn't think there was anything wrong.

On the other hand, I've read about people getting much better mileage than this. I've had the problem not just in LA's awful traffic, but in rural Florida it wasn't much better. Am I nuts or is there potentially a problem I can get serviced?

Thanks for your advice!

--Joe
Well, I can't tell you what's wrong, sorry. But there's something definatley not right. I have a 92 Eldorado and I get about 18-19 in Tampa traffic. You've got a pretty significant problem, and I'd think something should show up in the codes. There's no way that motor's running right, and the computer has to be recording something. Try and see what codes come up, then everyone will have more to go on with this.
Bob
 

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Yes, you should be getting much better mileage.... Spirited drivers here get about 17 in the city, give or take a few......

Check those codes and it should reveal problems..... If you dont know how to do it, turn on the ignition (not engine running) and press and hold OFF and WARMER until all the dash lights come on..... have paper ready, because youll want to write down the codes as the DIC spits them out....!

BTW..... Welcome to cadillacforums, thanks for signing up :welcome:
 

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Your mileage sounds find to me, big engine, big car shit mileage,
If you drive a caddy it not for the mileage, buy an echo
 

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airbalancer said:
Your mileage sounds find to me, big engine, big car shit mileage,
If you drive a caddy it not for the mileage, buy an echo
C'mon man. 9-11mpg ain't just cause he drives a caddy. That mileage is horrible... and if your car gets mileage like that you should see your guy and have him look at it. When were the plugs/wires/fuel filter/airfilter last changed? Maybe your heads needs a topclean. Are you using premium fuel? Check these things and run the codes and I'd be surprised if you didn't find your problem.
 

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My car gets better mileage than that, and I drive it like a madman, and the timing is off about 3-5 degrees because the knock sensors are bad......
 

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elwesso said:
My car gets better mileage than that, and I drive it like a madman, and the timing is off about 3-5 degrees because the knock sensors are bad......
You're right Wes. My parents had an early 70's Olds 98 wagon with a 455 and a quadrajet that got that many mpg. A 93 STS should get mileage comparable to, or better than my 92 Eldo. There's something wrong with it. I don't have a real light foot either.
Bob
 

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check the mileage tonite, it indicated 13 mpg,
The car is my wife everyday drive, she is about 6 miles round trip
The mileage on the highway is around 30
 

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Discussion Starter #10
Thanks for all the help guys. I checked the codes tonight and everything is in "history"...

P022, Open TPS Signal [VCC] & P070, Intermittent TPS Signal [VCC]. I don't know anything about the Throttle Position Sensor but it sounds like it wasn't working so well at some point in time.

In addition to that, I had a bunch of RSS codes, SO11,016,021, and 026 (all four "Damper Solenoid Valve Short to B+"). I also had S044, "Lift or Dive Signal Fault," and S055, "Resistor Module Short to Ground/Open".

Doesn't really sound like that related to my mileage problem, though I'd sure like to know what's going on there. I cleared the codes to see what comes up again in the next couple of days.

As far as fuel, yeah, premium only ofcourse. I don't know what brand of oil is in there truthfully, but it's not synthetic. I'll check into the filters, I don't remember if I did it on my last oil change. And a head topclean? I'll ask my mechanic (not that I have a good one.) ;-)

Thanks!

Joe
 

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You should be getting almost double that! What is the mileage of the car? Perhaps the cat converter is plugged up, or a muffler collasped because in these cases the engine has to work harder to "push out" the exhaust, and that MIGHT cause poor mpg.

Wes, thanks for inadvertingly reminding me how to check dash codes. For the second time now I saw the yellow service engine soon, and it bugs me, I'll have to check it! Then there's the dealership that told me you cannot check the codes that way probably because they want the 60 bucks for doing it themselves!
 

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Discussion Starter #12
Thanks for all the suggestions. It's got about 96,000 miles on it but I've had it since it's had 30,000 and it's always gotten this poor mileage.
 
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