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4.3 Vortec; Anemic or decent? Mine is weak...

Discussion in 'The Lounge' started by newyorkin, Sep 26, 2006.

  1. newyorkin

    newyorkin 1 ton status

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    I had the valves done on my 4.3 Vortec to fix the compression. I got 15mpg and crappy performance with the bad compression and misfire, and now I have a slightly smoother idle, but crappy performance and 14-15mpg. I couldn't pass inspection before because the bad valves were killing emissions, now I passed, but don't notice much difference in driving.

    A buddy with a shop told me that fuel economy sounds about right. I found a review of the 98 Blazer somewhere that said it gets 16mpg, and I figure with the bigger tires I'm probably losing that one 1mpg.

    So does this engine just suck and this is pretty normal?? Sometimes I have to bury the pedal to pass. This thing is making my old Dodge Intrepid look like a hybrid in economy and a vette in performance... If I'm going to be losing all this cash on gas, I might as well go back to a full size...
     
  2. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    I just bought a 96 K1500 with a 4.3 and NV3500. I'd say it performs better than my old 89 did with a 305 and 700r4. I was expecting a real dog, and I'm actually pretty satisfied with it, both with buzzing around town, and getting onto the freeway.

    Mine idles glass smooth, to the point I keep thinking I've stalled it, and has been averaging about 18 mpg in town thus far & got 24 mpg on the highway driving home after buying it...

    Apparantly they came rated at 200 hp from 96 up.

    I do eventually intend to swap the 4.3 out with a 5.3 V8 though, and put the 4.3 into my Toyota.
     
  3. readymix

    readymix 3/4 ton status

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    Besides a few NOS stickers the best way to get more power out ofthe 4.3 Vortec is............

























    In the garage with the rest of the tech
     
  4. yoshisv

    yoshisv 1/2 ton status

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    A good friend of mine has a 97 GMC Sonoma with the 4.3 and auto. That truck averages 22mpg with a powerdyne supercharger at 9psi.
     
  5. K5Greek

    K5Greek 1/2 ton status

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    how big are your tires? my dads s-10 gets about 16-17 with 30's. your number sounds about right and 4.3 are big engines i wouldnt expect them to get over 17-18 unless its strictly highway
     
  6. 1979jimmy350

    1979jimmy350 1/2 ton status

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    i had a 93 s-10 that would get over 20 on the highway i could see 17 depending on how i drove it, this was on a pretty high milage motor, but that thing was a good little motor, it handled hauling my k-5 on a 20 foot car hauler and still got 15 mpg
     
  7. newyorkin

    newyorkin 1 ton status

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    The mileage is stupidly consistent. We towed a trailer a couple weekends ago to Hershey PA and back, and did 15mpg the whole trip. It was 2 or 3 tanks of gas.

    The tires are not big at all, just 235's, but they're one or two steps up from factory. This thing is intended to get through snow, not really any wheelin'.

    Actually, Russ, you reminded me, I had a 92 k1500 with a 4.3 that was a beast, I used it to pull a couple small stumps around my property.

    This Vortec feels like it has no guts until it hits 5000. I've even manually gone through the gears to get some torque out of it, but that's a pita...
    The Vortec 4.3's were actually rated at 5hp less than a vanilla 4.3, which is what my 92 was. Sounds like a brilliant selling point :screwy: .

    I wonder if I have a clogged cat or vaccuum leak on the intake somewhere...
     
  8. 1979jimmy350

    1979jimmy350 1/2 ton status

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    235 did come stock, i had 235's with 3.42's in mine. The newer 4.3s are not rated at less thatn the older ones the TBI 4.3 was rated at 160 hp and the newer ones 190 hp
     
  9. Drey

    Drey 3/4 ton status

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    I have a 96 with the Vortec 4.3, 235/75R15s, 3.43 gears and auto tranny.

    I like it. I get between 15 and 19 MPG depending on if I can get out on the highway or not. I got a Magnaflow muffler on it a week or two ago and that has freed up some mileage I think. Im gonna make a posta bout it after this weekend.

    Has it popped any Error codes? I replaced EGR, Mass Airflow, in tank fuel pump, fuel filter, PCV, spark plugs, Air Filter and all 4 O2 sensors to get my to run as good as it does now. Back when I got it the damn thing wouldnt go much over 60 on gravel, it just didnt have the power
     
  10. BigOrange90Jimmy

    BigOrange90Jimmy 1/2 ton status Premium Member

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    Get rid of that mechanical fan and I'll bet it'll pick up 20 HP easy.


    Oh yeah:

    [​IMG]
     
  11. newyorkin

    newyorkin 1 ton status

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    Yeah, it was throwing a cyl #4 misfire code before I did the valves. Code went away and compression became good again after the valve job. Before taking the heads off, I did EVERYTHING to avoid that; plugs, wires, fuel spider, regulator, all filters, etc.

    I'm not saying 235's were not stock on XX Blazers. I'm saying 235's were not stock on this truck, maybe you guys got a different year or package. I think this one had 215's stock, I'd have to go look at the door sticker again. Don't know or care what the pinion is, though, I'm not changing tires far enough from stock to matter. The most mods I foresee doing on this truck are a couple more lights to illuminate my remote sites, and exhaust if it looks like the power bottleneck. I could probably deal with the mileage if the motor didn't feel so weak. I have thought about the fan... I have a couple electrics in the garage, but don't know what to do about a temp switch. Are there aftermarket temp switches around? I could probably mod the one from my bike into it...

    I'm not posting tech, dangit! I'm just wondering if this engine is a dog or not, it's my first Vortech and it only feels strong rolling downhill. Where's sled dog??
     
  12. BigOrange90Jimmy

    BigOrange90Jimmy 1/2 ton status Premium Member

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    You could probably get a thermostat controller from Flex-a-lite.

    I'm just picking on you about the tech thing. Hopefully no hard feelings there.

    If I had to start somewhere, open up the air intake and exhaust. They are both very restrictive, but I don't know how much you can do and still have it pass emissions.

    What grade gas are you running in it? Tires properly inflated?

    I know these are generic base questions, but they haven't been covered.
     
  13. newyorkin

    newyorkin 1 ton status

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    No hard feelings, I should've used a smiley up there.

    Yeah, tires are up and I'm using 87, no pinging or anything.

    I think this weekend I'll do the upper intake gaskets. I'm thinking vaccuum leak now. Maybe I'll run with the intake cover off and a piece of foam for a a day or two to see how that feels.
     
  14. BigOrange90Jimmy

    BigOrange90Jimmy 1/2 ton status Premium Member

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    What my best friend did on his 99 Blazer was remove the tube from the resonator that holds the radiator in place, then put a cone type air filter in it's place. It looks rough, but he's getting 19 MPG's running 29x10.50 TSL/SX and no lower valance on the front bumper. He runs all highway though 50 miles at a time. I don't know if the power levels are different or not between the years. You may want to try running 89 grade in it. Good luck with this!
     
  15. newyorkin

    newyorkin 1 ton status

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    Wow, 19mpg would Rock!! I do a lot of highway, too, about 50/60 miles a day at 60-80mph.

    I've tried 89, even 93 (I use a company gas card instead of expensing mileage sometimes, although I'd make more money expensing mileage...), the octane doesn't make a difference. I must have the cleanest fuel system on the planet, too, I've run a couple cans of seafoam through it, and a couple other cleaners over time.

    I should admit, I'm also really lazy with this truck, I put off any kind of serious wrenching until I have a laundry list or can't put it off. I work all day and then get 2 hours a night with my kids and if we can keep our eyes open, an hour or two with my wife, I hate blowing that time on stupid maintenance... I have a bald back tire on my bike and a new one in my basement, that's prioritized over the truck, but maybe I can get to both this weekend...

    Thanks for the help, btw all. I'll probably throw a post in the garage when I think I'll actually go outside and try something...
     
  16. BigOrange90Jimmy

    BigOrange90Jimmy 1/2 ton status Premium Member

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    I can't fault you there. Family has to come before everything.
     
  17. beater_k20

    beater_k20 Banned

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    what kind of truck are we dealing with? if its a C or K truck, consider yourself lucky getting that kind of milage. a 4.3 has no business in a fullsize truck.
     
  18. newyorkin

    newyorkin 1 ton status

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    It's a 98 S10 Blazer, or just Blazer now.

    I changed the drivers side plugs last night, and there was a pretty noticable improvement in performance. I'll find out next week if it made a difference in mileage...
     
  19. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    I must have a freak then... I chirped my tires hookin' second this morning when I slightly underestimated how fast the oncoming traffic was coming... That truck has plenty of power, and only uses about 30 bucks of gas, driving 20 minutes at 70 mph to the bus station, and 20 minutes back...

    My truck is a K1500 btw
     
  20. beater_k20

    beater_k20 Banned

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    my slug 305 would squeal the tires too, with 2.73 gears and a 700R4 and 30" tires, that happens when you dont have enough gear. drop it into an old 3/4 ton with a set of 4.10s, and it wont turn the tires for anything.
     

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