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sluggish when cold help

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by DMK, Oct 16, 2001.

  1. DMK

    DMK 1/2 ton status

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    Truck is very sluggish when cold once warmed up runs great. Have already changed coolent temp sender, map sensor. What should I check next. Truck is an 87 350 auto
    all emissions are hooked up. Also just changed wires, plugs,cap rotor and ignition moduale. Plugs did look lean.

    Thanks Doug
     
  2. Maybe it's just a cold blooded SOB like mine. If you do find a fix, let me know.

    God has a hard on for Marines, because we keep Heaven chock full of fresh souls!
     
  3. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    Do you have the stock air cleaner still on? If so, there should be a preheater hose attached to it that goes to the exhaust manifold. On the air cleaner side, there's a door that should be open letting warm air from the exhaust in when it's cold preventing sluggish running. It's a smog item also. Me, I run an open air cleaner so it runs sluggish when cold.

    Bubba Ray Boudreaux,
    "It wastes drinking time."<a target="_blank" href=http://community.webshots.com/user/mdntrdr1>http://community.webshots.com/user/mdntrdr1</a>
     
  4. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    I agree with Bubba.........Make sure that the vacuum-actuated door on your air cleaner housing is closed(sucking in hot exhaust air) when the engine is closed.

    Another thing to check is to make sure that your heat riser(on the exhaust pipe right below the passenger-side manifold) is closing when you start the truck. It's vacuum=actuated as well.

    If either of these pieces isn't working properly, the cold air that the engine sucks in at startup can actually coat the carb with a thin cover of ice, causing bad throttle response and poor idle. The more moisture in the air, the worse it will run....




    <font color=blue> NEVER FORGET, NEVER FORGIVE, NEVER SURRENDER<font color=blue>
     
  5. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    Don't know about all of them, but on mine, the door is controlled by a thermatic spring.

    Bubba Ray Boudreaux,
    "It wastes drinking time."<a target="_blank" href=http://community.webshots.com/user/mdntrdr1>http://community.webshots.com/user/mdntrdr1</a>
     
  6. DMK

    DMK 1/2 ton status

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    Everything connected, there is no heat riser on tbi. Anything
    else. Thanks for previous replys.
     
  7. CV202

    CV202 1/2 ton status

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    Interesting, the TBI on my 1990 has a heat riser coming off the passenger side manifold to the air cleaner housing.

    Why do people keep calling it a Bronco!!!!! [​IMG]
     

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