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Engines Surges

Discussion in 'GM Powertrain' started by Air Force One, Nov 12, 2009.

  1. Air Force One

    Air Force One New Member

    1990 Chevy 1500. Auto 305 V8. Engines surges...revs up high/low ...up/down...TPS, and just about every others componet has been replaced....Brakes are a little spongy...will having a Vacuum leak in the engine area affect the brakes??? Advise greatly appreciated...
     
  2. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner Gold Member 1000 Posts

    I would definately check for a vacuum leak for the surging.
     
  3. Air Force One

    Air Force One New Member

    When checking for a Vacuum leak...whats the best way? Using Carb cleaner and spraying around the hoses listnening to engine racing up?? Advise? Thanks!
     
  4. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner Gold Member 1000 Posts

    Using carb cleaner is on way to do it. Make sure there is no open flame or spark first:gasp: (always need warnings right?). with the engine idling spray along hose and fittings. If there is a leak the idle should briefly pickup then drop again. They can be very hard to find sometimes. A smoke test is another way but is done at a shop. Not sure of cost.
     
  5. Pizzot

    Pizzot New Member

    Idle Control valve

    If its while you are not moving, in neutral, parked, or any other time the truck is at idle and your getting the hi rev low rev its definitely the Idle Control Valve. I replaced mine and problem stopped.
     
  6. k.daddy1

    k.daddy1 Rockstar 100 Posts



    Spray around the base of the T/B. I've replaced a lot of the gaskets under the throttle body for the same defect your describing. Vaccuum leak will also cause it too. Good Luck!
     

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