Poor Gas Mileage
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Cadillac Catera and Cimarron Forum Discussion, Poor Gas Mileage in Past Cadillac Vehicle Discussion; I have a 1999 catera and I have noticed that over the past month or so the gas mileage is ...
  1. #1
    werwer2012 is offline Cadillac Owners Member
    Automobile(s): 1999 Catera
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    Poor Gas Mileage

    I have a 1999 catera and I have noticed that over the past month or so the gas mileage is getting really bad. I had it into the garage and they changed the air filter and plugs and it still is bad. I go 50 to 60 klms on a 1/2 a tank of gas and it cost me $32 to fill it up again. Can anyone give me any idea's what else they sholud check. Any help would be greatly appreciated.

    Thanks..Greg

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  3. #2
    JohnJJO's Avatar
    JohnJJO is offline Cadillac Owners Fanatic
    Automobile(s): 2000 Catera Sport
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    Welcome to the club of Low MPG. My cat can go only 240 miles on regular gas . And like 190 on premium. And I'm not flying around. Keeping my idle up to 3000rmp.
    OEM New spark plugs.
    Air filter, fuel filter
    Injectors hand cleaning and multiple time cleaners to the fuel tank was add + seafoam was preformed few times to.
    No help.

  4. #3
    gvjv3 is offline Awaiting Email Confirmation
    Automobile(s): 97 forest Green catera
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    Re: Poor Gas Mileage

    Hello

    what you might try is start the car and have someone run the RPM,s up, at the same time go to exhaust pipe and smell the exhaust, if really is strong than your burning rich, (more fuel than needed) The most common problem to this is a bad MAF, I took mine out and bought MAF cleaner, clean it and put it back, took off all the connection to it and but them back on, it work for me, might for you,

  5. #4
    werwer2012 is offline Cadillac Owners Member
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    Re: Poor Gas Mileage

    Thanks for the information. What is an MAF?

  6. #5
    MoistCabbage's Avatar
    MoistCabbage is offline Cadillac Owners 10000+ Posts
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    Mass Air Flow sensor.

    I'd suspect the FPR (Fuel Pressure Regulator) before the MAF.

  7. #6
    nethic is offline Cadillac Owners Member
    Automobile(s): 1998 Catera
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    Re: Poor Gas Mileage

    how much to replace both those parts ? I get the same issue but I'm almost positive its the o2 sensors (which I have brand new just can't put in since I have no jack )

  8. #7
    MoistCabbage's Avatar
    MoistCabbage is offline Cadillac Owners 10000+ Posts
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    Never priced either for a Catera, but FPRs are fairly cheap, MAFs can get expensive.

    Why are you replacing the O2 sensors? Is the CEL illuminated? Did you pull the codes?

  9. #8
    werwer2012 is offline Cadillac Owners Member
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    Re: Poor Gas Mileage

    I have heard that you can clean a MAS sensor. Is that something the average person should attempt?

    Greg

  10. #9
    nethic is offline Cadillac Owners Member
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    Re: Poor Gas Mileage

    Quote Originally Posted by MoistCabbage View Post
    Never priced either for a Catera, but FPRs are fairly cheap, MAFs can get expensive.

    Why are you replacing the O2 sensors? Is the CEL illuminated? Did you pull the codes?
    Not yet, my OBDII reader is on the way so I should have the codes pulled soon.

  11. #10
    MoistCabbage's Avatar
    MoistCabbage is offline Cadillac Owners 10000+ Posts
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    Yes, you can clean a MAF sensor. Not difficult in any way. Buy some MAF cleaner, remove the sensor, spray it clean, reinstall. If there are any codes for MAF voltage, cleaning it won't do a thing.

    If the CEL isn't illuminated, the O2 sensors are fine.

  12. #11
    werwer2012 is offline Cadillac Owners Member
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    Re: Poor Gas Mileage

    Thanks for the information...Greg

  13. #12
    JohnJJO's Avatar
    JohnJJO is offline Cadillac Owners Fanatic
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    Pass month was monitoring my mpg:
    2000 Cadillac Caters Sport with 153k miles, tire pressure was monitoring. Had full trunk of my tools, include prof. heavy jack. Newer air and fuel filter. OEM spark plug with approx. 20k on them. Engine oil Castrol GTX 5w-30 had approx. 3k of use when I started my mpg monitoring. Car was treated with Lucas and Seafoam frequently in a pass. During this time had no passengers and only me drove the vehicle.
    Results:
    Regular 87 - 16 mpg
    Premium 93 - 13.1 mpg

    Both time used Costco gas. Vehicle was driven in city only, in general keeped my foot on up to 3000rpm. But some time had to reached to 5000. I'm not crazy driver.
    I did saw the differents between 87 and 93 gas. Premium gave me better power and kind of stable. But It was not worst to lose 50 miles of driveble distance by using premium 93 gas....
    Any comments?......

  14. #13
    gvjv3 is offline Awaiting Email Confirmation
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    Re: Poor Gas Mileage

    umm, something up? I get better mileage with Premium than Regular, if I use Regular I get poor mileage and the engine pins, I adv about 25 mpg

    car5.jpg
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  15. #14
    JohnJJO's Avatar
    JohnJJO is offline Cadillac Owners Fanatic
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    Re: Poor Gas Mileage

    wow so what to do now?.......
    since i been have this car used regular

  16. #15
    cateralover1209 is offline Cadillac Owners Member
    Automobile(s): 2001 catera sport
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    Re: Poor Gas Mileage

    Well in my 2001 catera sport black i been having suspicions of the coolant bridge sensors theres two sensors on the coolant bridge.One is a single wire plugged on top of it and this sensor gives you the reading on your dash.the other one is a coolant temp sensor that tells your ECU(electronic control module) when it has reached closed loop so if that sensor is faulty youre runnig open loop for a longer period of time ,witch will kill youre gas mileage try looking into those sensors there only like 12$ each and try cleaning the ccv(cranck case ventilator )

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