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Stalling Blazer

Discussion in 'The Garage' started by katie, Aug 21, 2002.

  1. katie

    katie Registered Member

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    Guys and Gals
    I'm stumped i've got an 87 Blazer 305 TBI Auto 6" lift with headers and straight pipes and 35's. The truck stalls when its warmed up and you have the brake depressed to shift from Park to Reverse or Netural to Drive.It will also stall when you are coasting and depress the brake. I've done a major tune up, It threw 2 codes 1 for the EGR (i replaced) and the other was for the Oxygen Sensor (i replaced) problem still there. Im stumped what do you guys think? /forums/images/icons/confused.gif /forums/images/icons/confused.gif /forums/images/icons/confused.gif
     
  2. DUKE

    DUKE 1/2 ton status

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    I would say idle is too low. I imagine it was changed durring the tune up, maybe not for the better. But it starts okay? and will idle fine untill it reaches temp? or do you have to rev it to get her going?
     
  3. katie

    katie Registered Member

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    /forums/images/icons/confused.gif No you don't have to rev it. The truck idles ok
    and seems to idle ok when put in gear, it's when you change gears fast like backing out of the driveway. And now it will stall while your coasting and lightly apply the brake.. /forums/images/icons/frown.gif /forums/images/icons/frown.gif
     
  4. NEOMASTINO2U

    NEOMASTINO2U 1/2 ton status

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    i had an 87 k5 and just sold it to my brother in law, boy was it a pain! i ran into the same problem it would load up and die after it was warm i would drive it come to a stop and it would die, took it in and ended up paying for a new motor, (long story) any way didnt need a new motor, my pvc passages were clogged! might have that checked, its emissions the stuff is a pain, that and my tbi was gettin old needed a new one. this is just an idea to have that checked?! /forums/images/icons/smile.gif
     
  5. TopOff

    TopOff 1/2 ton status

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    Sounds like a vacuum leak after the tune-up.

    A vacuum leak can throw an EGR code, and the O2 code running lean. Which O2 code did you get?

    I would also think it is a vacuum leak because of "when you lightly press on the brake".

    Check brake booster vacuum line (I've broken the hard metal lines too many times to count), and all other vacuum lines into and around the cap and rotor (assuming you changed the cap and rotor when you did the tune-up).

    Good luck.
     
  6. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Almost sounds like some kinda funky torque convertor issue. The torque convertor is what hooks your eninge and transmission together. That have what you have heard before called "stall speeds". When the torque convertor gets spinning fast enough, parts inside of it "grab" and allow the power from the engine to the be transfered down to the transmission. Because of torque convertors, automatic transmission vehicles can idle while in gear and not stall out. The engine isn't going fast enough to make the convertor "grab", so it just sits there and spins until you press the throttle and raise the speed.

    Later model torque convertor have the feature where they "lock up". Most normal torque convertor when they "grab" are still slipping a little. So the eninge is making a few more turns than the transmission is recieving. When you get rolling down the highway, the torque convertor recieves the signal to lock-up so one turn of the engine means one turn to the transmission. This lowers RPMs and helps to increase mileage. Try coasting in Neutral and pressing on the break to see what happens. Thats probably not it though, but it makes me sound smart when I give big overdone explaniations /forums/images/icons/smirk.gif .

    It kinda sounded like you had a vacuum problem because brakes run off vacuum. The MAP sensor is always another good little deal to change when you are stumped.
     

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