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5 MPG On A Stock SBC?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by zcarczar, Sep 1, 2002.

  1. zcarczar

    zcarczar 1/2 ton status

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    Why would my truck be getting such crappy mileage. I have a stock 350, 700R-4 that i dont drive in OD in town, 10 bolts with 4.11's and 35" BFG's. I know something is not right here. Can you guys please help.
     
  2. poohisking

    poohisking Newbie

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    Is it running ok. Have you checked your plugs?
     
  3. zcarczar

    zcarczar 1/2 ton status

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    Put brand new delco's in it a week or two ago. I do have a intermittent check engine light that keeps giving me code 43. Ive replaced almost everything on that circuit too.
     
  4. Suffergauge

    Suffergauge 1/2 ton status

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    I don't know anything about the codes but..
    - check the vaccuum advance modgule (sp?) to see if it is advancing, that's like 5 mpg right there.

    - carb adjustment is a biggie, floats, jets, air / fuel mixture...

    - timing, it might not ping or act like it is out of time but chances are that it is.

    Jeff
     
  5. zcarczar

    zcarczar 1/2 ton status

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    Well I'm Running TBI so none of the carb stuff would have to do with it. Im thinking it is something to do with the check engine light coming on and then the engine going into failsafe mode.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Check engine light can't be helping. Get a scanner : )

    If you didn't change the speedo gears (or if electric change the setting) for the tires/gears, then the speedometer/odometer, thus the MPG figures, will be off by a certain %
     
  7. zcarczar

    zcarczar 1/2 ton status

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    My spedo is only off by a mile or two an hour, so it should say im getting better mileage than I am. Its throwin Code 43 at me which is ESC failure. I have a tech 1 at work that i can check it with.
     
  8. k20

    k20 3/4 ton status

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    mine was doing the check engine light thing too, only came on if u punched it then it stayed on till u cut it off. It ended up being my knock sensor. (mine was in the water jacket)
     
  9. zcarczar

    zcarczar 1/2 ton status

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    Its not that cause ive put 2 new ones on mine and it didnt fix it. So far ive replaced 2 knock sensors, ESC module and Ignition Module. Nothin fixed yet /forums/images/icons/confused.gif
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    If that tech1 lets you view data real time, pull out the manual and troubleshoot. The troubleshooting flow charts later on ('88 camaro for example) are excellent, not sure about the earlier manuals.

    Obviously you've got something wrong and you haven't fixed it, if you've got access to a scanner, not sure why you'd throw parts at it. (which I bet has started to get expensive) I believe all the stuff you replaced would show as good or bad in a scan, if you know how to interpret the data.

    I can't give specific scan examples, as I don't have anything scannable (yet) but when I do, I'm certain I'm going to have to learn what all the data means, and what it should be.
     
  11. 90K5

    90K5 1/2 ton status

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    Hey man, I've got the same problem with the code 43. It'll throw it every now and then. I borrowed some parts of a friend's truck and it still did it. Borrowed the knock sensor, and some other ESC stuff - don't remember what it was - and I still get it every now and then. If you find out anything, please post up.
     
  12. Blue85

    Blue85 Troll Premium Member

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    Boy, this sounds familiar. I know that somebody else was getting code 43 not too long ago. You might search for that and see if they figured it out. Sounded just like your story. Or was it you? /forums/images/icons/smile.gif
     
  13. 90K5

    90K5 1/2 ton status

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    It might have been me. I did a lot to try and hunt it down and then gave up. I have good gas mileage though, get aobut 12 no matter what, with 4.11's and 33's, otherwise same setup as you
     
  14. wrathORC

    wrathORC 1/2 ton status

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    It's been a while since I've had a TBI truck but how is it running? Are the plugs real dark? Oxygen sensors/MAP sensors can play games with you. Oxygen sensors have a habit of going silently and persuading the computer to run the truck at full rich. They're cheap at $18 the last time I bought a Bosch one.

    I'd be thinking that you might have a black-haired bandit running away with your petrol. I've never heard of a bone-stock TBI vehicle (not even a big block) that used that much gas without running so bad it couldn't get out of its own way.
     
  15. zcarczar

    zcarczar 1/2 ton status

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    I have the facotyr driveability manual sitting in my truck. I will just have to find the flow charts you were talking about. Ive been pretty lucky, I got an 88 suburban that my dad has been letting me swap stuff off of. Plugs are brand new, less than 1000 on them. A technician said that i should check the map sensor with a vaccum gauge and the tech 1 while driving to see if the map sensor is working. I will also have to check the O2 sensor. When the scanner is on it will say whether it is rich or lean and the 0@ cross counts changing when the truck is on. I just need to get off my lazy but and fix it i geuss.
     
  16. jpdrake

    jpdrake 1/2 ton status

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    im very limited in my tbi know how. ive just rebuild my 88 350tbi. <new egr valve, new knock sensor, new o2.> got it registed today threw the plates on took the top off and went for a ride in it for the first time in over a year. it just dosnt have that crisp throtle responce, runs real rough from idle to 1200rpm. can i get some help? i need to pass MA emisions by next fri.
     
  17. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    dump some of that "garentied to pass" stuff into your tank. You can find it at autozone next to the fuel system cleaner. I've never used it myself, but I here that it will reduce emissions greatly for the tank that you put it in.
     
  18. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    You can't imagine...

    My truck ran awesome going into inspection, so I knew my numbers would be pretty good.. But I dumped a can of that into it for the tankfull prior to emissions, well, my numbers where less than a 1/3rd of what they allowed... :eek1: :bow: :haha:
     

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