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Thread: Terrible MPG

  1. #11

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    Information about the IAC (Idle Air Control) valve can be found here http://www.2carpros.com/forum/1999-c...-vt323585.html

    My description of the affects of a bad IAC are as follows:

    -less responsive throttle
    -truck seemed to idle to 1000rpms with a bit of a rough idle

    Now there are a lot of different parts to check, but after I replaced this, I have been noticing good changes in the response and idle is a lot smoother. Does this affect MPG? I don't know for sure as I will do a comparison (before I seemed to go 284 miles a tank) 21 gallon tank=13mpg which is mostly city driving.

    The IAC located on my 95 chevy 1500 (4.3L V6 Vortec TBI) (this is just below the TBI)


    A print out from Auto-zone about checking this states:
    1. Disengage the IAC electrical connector.
    2. Using an ohmmeter, measure the resistance between IAC terminals A and B. Next measure the resistance between terminals C and D.
    3. Verify that the resistance between both sets of IAC terminals is 20-80 ohms. If the resistance is not as specified, the IAC may be faulty.
    4. Measure the resistance between IAC terminals B and C. Next measure the resistance between the terminals A and D.
    5. Verify that the resistance between both sets of IAC terminals is infinite. If the resistance is not infinite, the IAC may be faulty.
    6. Also, with a small mirror, inspect the IAC air inlet passage and pintle for debris. Clean as necessary, as this can cause IAC malfunction.
    Hope this was some help. Sorry for the mammoth picture.
    Last edited by liquidmetal; 01-26-2010 at 11:12 AM.
    ----------------------------------------------------------------------------------------------


    Vehicles owned:
    1995 Chevy Cheyenne 4.3L V6
    1972 Chevy C-10 (on storage lot, fathers but part of the family chevys!)

  2. #12

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    mostly city i dont go highway to much. mostly from home to school/friends so theres no need for highway use

    and yes i like to stomp on the gas every now and then but not at every stoplight

  3. #13
    Master Mechanic Big75's Avatar
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    city eats it up. still not sure if that will get you 7 alone though.
    This post has been rated MA LSV, and is intended for mature audiences. Reader discretion is advised. :fighting0037:
    ghst-_-R3CON83 ----------BATTLEFIELD BAD COMPANY 2----------------------

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  4. #14

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    Quote Originally Posted by liquidmetal View Post
    Information about the IAC (Idle Air Control) valve can be found here http://www.2carpros.com/forum/1999-c...-vt323585.html

    My description of the affects of a bad IAC are as follows:

    -less responsive throttle
    -truck seemed to idle to 1000rpms with a bit of a rough idle

    Now there are a lot of different parts to check, but after I replaced this, I have been noticing good changes in the response and idle is a lot smoother. Does this affect MPG? I don't know for sure as I will do a comparison (before I seemed to go 284 miles a tank) 21 gallon tank=13mpg which is mostly city driving.

    The IAC located on my 95 chevy 1500 (4.3L V6 Vortec TBI) (this is just below the TBI)


    A print out from Auto-zone about checking this states:
    Hope this was some help. Sorry for the mammoth picture.

    wow this is great. thanks alot!

  5. #15

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    Quote Originally Posted by Silverado1500 View Post
    haha you and me both. i might be switching with my dad and drive the truck on the weekends
    what does he drive?

    '01 Chevrolet S10
    -custom air intake
    -painted dash
    -footwell lights
    -Strange Performance stickers
    -exhaust coming soon
    -Xplod Head Unit with iPod connectivity
    -12" Sony Xplod woofer
    -Majestic 400 watt amp, bridged

    If at first you don't succeed, then skydiving is not for you.
    :party:

  6. #16

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    Quote Originally Posted by Stealth View Post
    what does he drive?
    toyota camry. that thing is beast on MPG ahahah. but i hate drivin it over my truck.

  7. #17
    Legend

    Join Date
    Feb 2008
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    Red Wing, Minnesota, United States
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    Default

    So all you do is drive in town. if thats the case its gonna be bad, my sister has a 1998 blazer same thing, NEVER on the highway and she just drives 2 miles to work then home. the truck can not get to operating temp which will give it really crappy mileage.
    99 K1500 Suburban LT "THE BEAST"
    Hypertech III, K&N, true dual
    285/75/16
    ___________________________
    Jason

  8. #18

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    yeah in town short driving kills mpg. i'm only like 2 miles from my work so if i floor its or just little heavy on the gas i get 10-12 mpg. but if i drive to my parents a hr away then the mpg is alot better. and a 4 banger s10 will get about the same in town if you drive the same way. my brother had a '00 s10 that sucked on gas. it was totally stock and got worse mpg then my truck. just my 2 cents.
    Peter

    2007 Silverado LT Crew NNBS 5.3
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    Work in Progress
    1952 Chryler 2dr Windsor } Mine and Dad's
    Former Cars
    2000 civic hx Moded
    1993 Probe simi moded
    1985 Nissan 4x4 Kingcab

    So*Cal Group

  9. #19

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    alright so i cleaned my throttle body with a toothbrush and the cleaner today and man was it nasty. hoping this will up my MPG

  10. #20

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    oh and another thing. a can of seafoam says to put 1/3 of it in gas tank. well if i have a 26 gal should i pour half of the bottle or all of it?

    which would you prefer?

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