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88 k5 with TBI idles high please help !!!!

Discussion in 'The Garage' started by dynoram, Jun 6, 2004.

  1. dynoram

    dynoram Registered Member

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    Hey all well just got my mitts on an 88 k5 blazer with TBI. The guy i inherited it from recently changed the tranny and i suspect its downfall was this high idle problem. Soon as i got it i attacked and changed the Intake Air Control Valve and the oxygen sensor both didnt help. I attempted to turn the torqs head screw located in the drivers side of the throttle body and it didnt respond. I try'd disconnecting the IAC and adjusting it again still no reaction. This bug is driving me nuts you guys got any ideas what i should try next? I searched for a vacuum leak and found nothing what do i do next? /forums/images/graemlins/confused.gif /forums/images/graemlins/k5.gif
     
  2. hefty53

    hefty53 Registered Member

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    in a spec book ( chilton, hayes) they give you the resistance figures for every sensor in the motor, you can chenck most alone and it doesn't take long, you only need a test meter. i had my coolant temperature sensor go bad and it over fueled my motor to the point of hydrolocking it, replaced it ($15 ) and it was fine, you could also try replacing the fuel meter in the tbi if the bladder springs a leak it will richen your mixture and could cause a higher idle.
     
  3. hardcore71

    hardcore71 Registered Member

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    throttle body gasket getting sucked in is a very common problem on tbi truck motors. spray around the bottom of the t-body w/ carb clean to check if it is leaking. or you could just unbolt the 3 t-body to intake bolts and have a look. That is the #1 cause of high idle that i have seen on these trucks.
     
  4. dynoram

    dynoram Registered Member

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    Ill gove it a try thanks!
    The exhaust does smell a bit rich....
    I also forgot to mention i ran my hand down the bottom of the intake snorkel and there was an empty provision possibly for an intake air temp sensor? I just got the truck ill pick up a repair manual this week.
     
  5. scoutillac

    scoutillac 1/2 ton status

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    How is the timing? I also found part of my TB gasket gone causing it to run rich. It seems to have a higher idle when the vacuum tubes come loose from the front of the TB or the canister on the inside of the drivers fender well.
     
  6. chevyjeff

    chevyjeff 1/2 ton status

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    If its going from open loop (cold start) to closed loop (operating temp) I would suspect a vacuum leak of some sort. If you find that you have no vacuum leaks at all I would check you temp control sensor located on the front of the intake. Is it throwing any codes? (ses light) Also check www.thirdgen.org tons of good tbi info there.
     
  7. b55baron

    b55baron Registered Member

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    I had the high idle problem on my '89. Replaced the throttle body gasket and no more problem.
     

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