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  1. #1

    Default Advice for my 1994 Suburban

    Hey all,
    I have a new to me 1994 Suburban k2500. It has a 5.7lt V8, automatic transmission and it is a 4x4. I am currently getting 14 mpg and would loeve for this to increase. I live in rural Montana the winters see -37 and the summers see the 90's so I am unsure if a cold air intake would help and they cost around $300.00 and I am not sure how much of an increase they make. Does anybody have any "proof" from your experince?

    I also need to put on a new muffler. What brands/type do you use?

    I am using 10-30 Napa oil with a Napa oil filter. I am not oppessed to changing brands. I just like the price of Napa products.

    Are there better spark plugs and wires then just the stock ones in there or are they all abotu the same?

    The tires are the rigth size and the air pressure is fine.

    I have also been told a super chip will help out, but again $300.00 is a lot of money.

    Thank you for any advice.
    -M
    http://i339.photobucket.com/albums/n449/lqjoe16/raiders.jpg
    1994 Suburban 5.7
    Automatic 4x4
    14 mpg

  2. #2

    Default

    If the 5.7L is a TBI motor, then just flip the lid on the filter housing upside down. Also, if it's a TBI, then take a look at a TB spacer, I have the one I got listed in my signature, and I saw about 3-5mpg increase (depending on my driving) on the highway plus a nice little bump in power.

    For spark plugs, I like to use NGK or Denso. Stay away from Bosch, not that they're necessarily bad, but I never saw any increases that justify the extra cost.

    For mufflers, mine is listed in my sig (sorry, I can't remember brand names off the top of my head). I remember being told by all the muffler shops in my town that this brand of muffler was designed to help "pull" the exhaust through and increase power and mileage. Don't know if it actually helped or not since I had the exhaust done the first week I had the truck.
    Scott

    ΜΟΛΩΝ ΛΑΒΕ

    '94 Chevy Suburban K1500
    3" exhaust w/ aero turbine non-baffled muffler
    CFM Technologies TB spacer
    CB w/ 44" whip antenna


  3. #3

    Default

    A fellow Montanan!

    #1 - Switch to 5W30 this winter. 10W is to thick when it gets below zero.
    #2 - Change out your distributor and rotor cap every year. This often goes overlooked and it makes a big difference.
    #3 - Use Delco plugs gapped at .040 instead of factory .060 - Everyone on here including me swears by the .040 gap
    #4 - If the plug wires have never been changed, get some decent 8MM plug wires
    #5 - If you have never replaced the O2 sensors, replace them both up and down stream
    #6 - On the muffler, Flowmaster or Magnaflow seem to be the popular choices, but the exhaust is a stock 2 inches so unless you change out the Catalytic converters the muffler is a small increase versus the other things mentioned.

    I regularly get 18-20 on the highway using cruise control and ignoring the urge to go 75. We drive at 65 here even though everyone else is flying around us.

    --Joe

  4. #4
    Legend

    Join Date
    Feb 2008
    Location
    Red Wing, Minnesota, United States
    Posts
    3,356

    Default

    Quote Originally Posted by EvilNetwork View Post
    A fellow Montanan!

    #1 - Switch to 5W30 this winter. 10W is to thick when it gets below zero.
    #2 - Change out your distributor and rotor cap every year. This often goes overlooked and it makes a big difference.
    #3 - Use Delco plugs gapped at .040 instead of factory .060 - Everyone on here including me swears by the .040 gap
    #4 - If the plug wires have never been changed, get some decent 8MM plug wires
    #5 - If you have never replaced the O2 sensors, replace them both up and down stream
    #6 - On the muffler, Flowmaster or Magnaflow seem to be the popular choices, but the exhaust is a stock 2 inches so unless you change out the Catalytic converters the muffler is a small increase versus the other things mentioned.

    I regularly get 18-20 on the highway using cruise control and ignoring the urge to go 75. We drive at 65 here even though everyone else is flying around us.

    --Joe
    I would agree with everything but the changing the distributer and rotor every year seems a little overkill.
    99 K1500 Suburban LT "THE BEAST"
    Hypertech III, K&N, true dual
    285/75/16
    ___________________________
    Jason

  5. #5

    Default

    Quote Originally Posted by vncj96 View Post
    I would agree with everything but the changing the distributor and rotor every year seems a little overkill.
    To each his own.

    Back in the day when distributor caps and rotors were the norm, it was recommended to change them about every 15,000 miles or couple of years. As the rotor spins around and around the cap, the gap begins to widen with age just as with spark plugs. I drive about 17,000 a year on average. Therefore I change it once a year. Most people never know it needs to be changed because these 5.7's were one of the last motors to have them.

  6. #6

    Default

    caps and rotors are very basic things the only fault to keep an eye on would be carbon tracking cracks in the plastic and worn contacts so if you see none of these and you buy the good brass caps and rotors you can run them for a few years without any noticable loss in performance

    99 tahoe 2 dr. 4x4 7.4 4L80-e NP246, SAS, dana 60 hp, sterling 10.5 rear, gibson headers, and alot of tricks of the trade !!!!!!IF YOU'RE NOT CHEATING YOUR NOT TRYING!!!!!!!!

  7. #7

    Default

    Quote Originally Posted by ct9a View Post
    If the 5.7L is a TBI motor, then just flip the lid on the filter housing upside down. Also, if it's a TBI, then take a look at a TB spacer, I have the one I got listed in my signature, and I saw about 3-5mpg increase (depending on my driving) on the highway plus a nice little bump in power.

    For spark plugs, I like to use NGK or Denso. Stay away from Bosch, not that they're necessarily bad, but I never saw any increases that justify the extra cost.

    For mufflers, mine is listed in my sig (sorry, I can't remember brand names off the top of my head). I remember being told by all the muffler shops in my town that this brand of muffler was designed to help "pull" the exhaust through and increase power and mileage. Don't know if it actually helped or not since I had the exhaust done the first week I had the truck.

    What is a TBI? and what is a TB Spacer?
    http://i339.photobucket.com/albums/n449/lqjoe16/raiders.jpg
    1994 Suburban 5.7
    Automatic 4x4
    14 mpg

  8. #8

    Default

    Hey Everyone thanks for the advice. If have any more keep it coming!
    http://i339.photobucket.com/albums/n449/lqjoe16/raiders.jpg
    1994 Suburban 5.7
    Automatic 4x4
    14 mpg

  9. #9

    Default

    I agree with Dr. Evil's list Go with AC Deco for all your ignition components. For wires, Napa Premium are fine, and usually a little cheaper. Also check your TB to intake gasket. They are notorious for going bad. The SeaFoam treatment is also a good idea. Don't forget your air and fuel filters too. The TBI should have only one O2 sensor.

    Napa filters are highly recommended, just get the Napa Gold.

    At the end of the day, this is a thirsty truck. Do you have overdrive? I don't know when the switch was made from TH400 to 4L80e in the 2500s. It's a 3/4 ton truck, with probably 4.10 gears, 3.73 if your lucky. Keeping your speed down will help more than anything.
    When you hear hoofbeats, look for horses not zebras.

  10. #10

    Default

    TBI = Throttle Body Intake
    TB = Throttle Body
    Scott

    ΜΟΛΩΝ ΛΑΒΕ

    '94 Chevy Suburban K1500
    3" exhaust w/ aero turbine non-baffled muffler
    CFM Technologies TB spacer
    CB w/ 44" whip antenna


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