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  1. #1

    Default how to up my MPG

    Hello,
    I was curious , how would I up my mpg ?

    My suburban is a 1995 , 1500 with a 350 I believe ...and it has a carburator

    I know by experiance with past vehicles that spark plugs , CAI , and a few other things help , but I've never owned a vehicle with a carburetor so what can I do . I currently get about 11 city 15 hwy ...completely stock , new fuel filter brand new stock paper filter and recent oil change ..thanks in advance !

  2. #2
    Jr. Engineer
    Join Date
    Feb 2012
    Location
    Western Maryland/Wyoming
    Posts
    292

    Default

    Andy, Your Suburban should have TBI, throttle body injection, and not a carb. I had a 95 and could get almost 20 mpg, on the highway. Totally stock except for synthetic oil and lubes.

  3. #3

    Default

    As said already, it's not a carb, but a TBI system (which looks like a carb, but is just a big throttle opening, with a fuel injector).

    Biggest things that will help you is keeping the engine oil, filters, and fuel system well maintained; and keeping the tire pressure up near the max for your tires (probably around 42 PSI), keeping the load down (empty cars are lighter cars), and keeping your foot out of the floor when accelerating.

    Plugs won't really help (unless yours are worn out, or poorly indexed or gapped). A CAI kit for your truck won't really help either, as it doesn't eliminate what appears to be the problematic piece in the intake tube, which is the neck on the filter housing. A filter housing that kept the neck leading to the air intake tube on the side, more close to round, would be helpful, but probably not enough to get excited about.

  4. #4

    Default

    Thanks guys . I usually stay at around 2000 rpm or lower to save gas and tire pressure is fine ...could be that the motor has over 300k miles on it lol . I was just hoping there was some mods or something that I could do to increase the mpg . I have the original dealer paper that goes in the window and it says 13mpg hwy

  5. #5

    Default

    Quote Originally Posted by Andy_Panda View Post
    Thanks guys . I usually stay at around 2000 rpm or lower to save gas and tire pressure is fine ...could be that the motor has over 300k miles on it lol . I was just hoping there was some mods or something that I could do to increase the mpg . I have the original dealer paper that goes in the window and it says 13mpg hwy
    Well if it says 13, and you're getting 15, sounds like a win to me.

    But there isn't really much you can do on the older TBI engines in ways of simple mods to gain a MPG or two. And that's all you would get, if you could do the mods to get them. There's one injector for all eight cylinders, and it's at basically the furthest reasonable point from the intake valve that it can be. So you can't really do much in the way of tuning. The intake system doesn't have any huge/odd bottlenecks that a CAI would help get rid of. The main issue with the intake system is that it goes from a 3" circle to an almost flat rectangle at the neck of the filter housing.

  6. #6
    Legend

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

    Default

    I disagree, you should be getting better, when my parents had there 92 we could pull 22 mpg at 75 mph loaded with three kids and luggage. The old TBI are much easier then the vortec motors to squeeze more mpg out of. New distributor, wires and plugs will help greatly. Also have you ever changed diff fluids? Just getting some new fluid in the rear differential will help. Just get a stock replacement K&N and make sure the timing is correct.
    99 K1500 Suburban LT "THE BEAST"
    Hypertech III, K&N, true dual
    285/75/16
    ___________________________
    Jason

  7. #7

    Default

    What's your tire size? I lose just about 3 miles per gal with my larger more aggressive tires versus my stock old man winter tires. Other than that... ya need to keep you foot off the throttle...
    2009 Chevy Silverado 2500HDLT 6.0L w/ Towing Package, Dick Cepek GM8 Rims, Dick Cepek FC II 33X11.50R17,RKSport Ram-Air Hood(Functional), Lazer Lite Aluminum Tonneau Cover, Road Armor Stealth Bumper, PIAA Lighting, Diablo Trinity Tuner, Diablew Custom Tune, BullyDog Cold Air Intake, American Racing Headers w/highflow cats, Corsa Performance Sport Exhaust, Custom Striping, Black Bowties front and rear, Fuel Grille Inserts, Recon Headlights, Readylift Shocks, Readylift Upper Contol Arms, 2" Blocks in the Rear..

    Future Plans: HD Tie Rods, Under hood upgrades, Crower Camshaft and possibly electric fans.

  8. #8

    Default

    Quote Originally Posted by TimTom64b View Post
    What's your tire size? I lose just about 3 miles per gal with my larger more aggressive tires versus my stock old man winter tires. Other than that... ya need to keep you foot off the throttle...
    Lol my tire size is p235/75R15 so I don't think its the tires

  9. #9
    Sr. Apprentice
    Join Date
    Jun 2013
    Location
    1391 N Jefferson St., Anaheim CA 92807
    Posts
    65

    Default

    Best way to uo MPG are accelerate slow and gradually get to the speed desired.Accelerating fast at stop signs and red lights is not needed,because you are using three times the gas needed every single time you do this,.Proper inflated tires, most tires run at 40 psi, some a little less, keep proper air pressure as often as possible.) clean proper gapped plugs is always best, if a plug has build up of carbon on it it will not function as good and will use more fuel to get the job done.Oil should be kept in clean to decent condition,change it when needed to get better performance.

  10. #10
    Legend

    Join Date
    Jun 2006
    Location
    River Ridge Louisiana-4 miles W of New Orleans-didn't flood-water stopped 800 yards away.
    Posts
    1,612

    Default

    Andy
    I looked up EPA site-the mpg ratings-
    I will post 2 sets 2 for 2wd 2 for 4x4
    The 1st is the rating on your window sticker-the second is for the revised rating(revised 2008)

    2wd original ratings 1995 city=13 combo=15 hy=17
    2wd revised 1995 city=12 combo=13 hy=16

    4wd original 1995 city=12 combo=13 hy=15
    4wd revised 1995 city=11 combo=12 hy=14

    The original 1995 combo rating for 4wd was 13 mpg
    In any case your 11 mpg city- is not bad-and indicates your vehicle is in decent shape despite miles and years
    Now 15 mpg hy- is what you would expect at a steady 70 mph or more- or if you have a little city mixed in-which is the usual case

    Your mpg sounds ok
    You could improve your city mpg by pulse and gliding.The old "drive like you have an egg under accelerator" doesn't work as well as pulse and glide.
    Our transmission-most GM truck ATs- are perfect for pulse and gliding because they "disconnect" when you lift your foot completely off the gas-no engine braking at all-just as if you put it in N when it is still in D

    Motor on Pulse and glide is worth about 5-10% more than egg under accelerator- 15-20& more than driving normally
    Pulse and glide-
    Just accelerate normally-not gently-up to posted city speed limit-lift off-you will actually peak at about 37 mph if you lift at 35mph- then glide down to 28 mph- you glide will be about 27-30 seconds and it will carry you about 1/4 mile.So one pulse glide cycle will be about 1/3 mile-
    In many cities this will carry you from light to light
    If not just repeat.
    GM engineers removed engine braking in the ATs-clever transmission trickery-to get you better mpg
    Partially Explains part of how they get such good mpg from 5000 lb BLOCKY V-8 powered vehicles.

    Pulse and glide-with motor on and left in D- works great in GM trucks
    Luck
    Charlie
    PS as other said-tire pressure important-CAI exhaust mods all motor bolt ons-waste of money for part throttle FE- GM engineers know their business-forget trying to beat them with some BS bolt on-won't happen

    PPS- your 3rd row weighs about 80 lbs-if you don't need it-remove it- but you won't be able to measure the improved FE- 80 LBS 1.6% weight loss- figure maybe improve city FE by 1/2 that at best-much less than .1mpg

    PPPS Syn oil say mobil 1 5w30 will help FE -but not enough to measure-same store on syn diff lube-good idea-but you won't be able to measure any difference-many folks swear by amsoil or royal purple

    My point on modifying how you drive will produce gains you can measure-and our GMs have the ATs that are designed perfectly for motor on P&G -
    dropping hy speed improves mpg measurably also-
    depends on local conditions but you can usually run 4 -6 mph less than posted limit without getting run over from behind-some places you can't but most you can
    Last edited by phoebeisis; 08-15-2013 at 07:12 AM.
    1998 suburban-
    1/2 ton

    199500 miles
    River
    Ridge,LA

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