Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

sudden mpg problem

Discussion in 'The Garage' started by suthrnchvyguy89, Apr 13, 2005.

  1. suthrnchvyguy89

    suthrnchvyguy89 Registered Member

    Joined:
    Oct 10, 2004
    Posts:
    51
    Likes Received:
    0
    Location:
    charleston, sc
    about a week or two ago my truck started gettin horrible gas mileage and im not sure why. its always been bad but recently it is easily twice as bad as it was before.

    i already changed the spark plugs and wires to see if that would help... it didnt lol. the weather has been warming up here lately so ive starting driving with the windows down but i dont think that would make too much of a difference.

    i heard somewhere that it might be some sensor in the tbi that went bad... do yall know what it might be and how much it would cost to get it replaced?

    edit: im gonna change the fuel filter this weekend to see if that would help too.
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,172
    Likes Received:
    1,381
    Location:
    E-town baby!
    Might be a bad O2 sensor...

    Rene
     
  3. durantk5

    durantk5 Registered Member

    Joined:
    Mar 1, 2005
    Posts:
    50
    Likes Received:
    0
    Location:
    Greensboro, NC
    it could also be a bad map sensor. mine went bad and kept fouling my plugs cause it was making it way too rich.
     
  4. suthrnchvyguy89

    suthrnchvyguy89 Registered Member

    Joined:
    Oct 10, 2004
    Posts:
    51
    Likes Received:
    0
    Location:
    charleston, sc
    i knew i was forgeting sumthin... yeah that got replaced about a month or two ago also.

    what is a map sensor?
     
  5. big jimmy 91

    big jimmy 91 1/2 ton status

    Joined:
    Feb 21, 2004
    Posts:
    639
    Likes Received:
    0
    Location:
    Northwestern Ontario Canada
    I have seen a plugged catalytic convertor cause a car to use more than double the fuel it used to.
    :eek:
     
  6. RustyMule

    RustyMule Registered Member

    Joined:
    Dec 18, 2004
    Posts:
    73
    Likes Received:
    0
    Location:
    Westford, MA
    Is the check engine light on?
     
  7. azblazer69

    azblazer69 Registered Member

    Joined:
    Jul 10, 2004
    Posts:
    30
    Likes Received:
    0
    Location:
    Phoenix, AZ

    Yeah... That is what I was going to say too.
     
  8. suthrnchvyguy89

    suthrnchvyguy89 Registered Member

    Joined:
    Oct 10, 2004
    Posts:
    51
    Likes Received:
    0
    Location:
    charleston, sc
    crap i forgot to tell you that too... i have long tube headers and a true dual flowmaster exhaust without cats. and yes the check engine light does come on occasionally but when i took it to the shop awhile back, the guy said it was just because of the exhaust.
     
  9. RustyMule

    RustyMule Registered Member

    Joined:
    Dec 18, 2004
    Posts:
    73
    Likes Received:
    0
    Location:
    Westford, MA
    If you have a compy controlled truck, it needs an o2 sensor to tell the computer how it is running. If it/they have been diconnected, the compy throws a code and uses other sensors to "fill in the gaps" left by the missing signal. After a while it runs everything to its limit and the engine runs worse and worse. Go to a shop and have them check the codes. Then tell us what happens.
     
  10. cbbr

    cbbr 1 ton status GMOTM Winner

    Joined:
    Jul 17, 2004
    Posts:
    14,681
    Likes Received:
    0
    Location:
    High velocity, Low altitude
    Begin Hijack* Will a bad O2 sensor, along with the drop in MPG also cause the engine to miss or "stutter" at certain speeds. *Hijack Over
     
  11. RustyMule

    RustyMule Registered Member

    Joined:
    Dec 18, 2004
    Posts:
    73
    Likes Received:
    0
    Location:
    Westford, MA
    The o2 sensor is more of a "broad stroke" sensor. It tells the compy the state of things in the engine over time. If it is a specific rpm or speed, I would look into a bad MAP, TPS or speed sensor (if it has them).
     

Share This Page