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Idle Problems

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KapeKodK5, Aug 9, 2000.

  1. KapeKodK5

    KapeKodK5 Registered Member

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    I have a 1990 k-5 with a idle problem. It idles up and down with or without any accessories on. Almost to the point where it sounds like it will stall then goes back to normal idle for a few seconds then back down . This just goes on and no. ANy ideas of what is wrong or what sensory is shot
     
  2. K5experience

    K5experience Registered Member

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    Try changing the fuel filter
     
  3. River

    River 1/2 ton status

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    Try reseting the computer by taking off the batery cable for 5 minutes. Some times this will help.

    I had a simular problem but my idle went from 600rpm to 2000rpm on and on in the and it was the temparture sensor from the coolant in the intake manifold.

    Goes your service engine soon light on?

    Greetings from Amsterdam,

    River `89 K5, 350, TH700R4, NP241, "33, 2.73, 10 bolt F, 12 Bolt R
     
  4. Emmettology 101

    Emmettology 101 3/4 ton status

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    If your CEL isn't coming on then you may have an intake or vacuum leak.

    Check by sraying some carb cleaner or propane around the intake and base of the carb. i guess propane works better, but I haven't tried it.

    Mike [​IMG]
    1982 GMC Jimmy - <font color=green>Emmett</font color=green>
    http://emmett.coloradok5.com
     
  5. Scoobydoo

    Scoobydoo 1/2 ton status

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    What about the O2 sensor on the exhaust?
    and/or the TPS (Throttle Position Sensor)?
    Unfortunately, I don't know of any way to test either of these?(anyone?), just replace them one at a time and see what happens[​IMG]
    I would bet it is one or the other, since they both tie directly to your idle and throttle.
     
  6. realsquash

    realsquash 1/2 ton status

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    It wouldn't hurt to disconnect the battery for 5 minutes or more so the computer forgets what it learned. BUT, the computer doesn't learn anything at idle that will make it surge like that. You could have a faulty IAC motor, a vacuum leak, possibly other things too. Does your SES light come on?

    Squash
    http://www.trailrunners4x4.org/users/realsquash
     
  7. Emmettology 101

    Emmettology 101 3/4 ton status

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    You would get a check engine light with these being bad.

    AH, it could be a TBI gasket right under the TBI. These were prone to going out after a while and dont cost much to replace. I had to replce the one on my 88 Chevy Van that had under 100K on it.

    Mike [​IMG]
    1982 GMC Jimmy - <font color=green>Emmett</font color=green>
    http://emmett.coloradok5.com
     
  8. realsquash

    realsquash 1/2 ton status

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  9. Nate87k5

    Nate87k5 Registered Member

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    Check the simple things first. I had the same problem in my 87 with TBI. I anaylized the crap out of it, never looking at the simple things. Ended up being a bad spark plug wire. It was causing an arc from the plug wire boot to the spark plug heat sheld. The idle would be steady while it wasnt arcing and would drop when it did. I replace the set of wires for 30 bucks and problem fixed.
     
  10. det45

    det45 1/2 ton status

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    My 89 K5 did the same thing and all it needed was the O2 sensor replaced. That's you're problem..Det45
     
  11. BillyBob

    BillyBob 1/2 ton status

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    My 87 sometimes idles rough untill the engine is running for a few min.. it feels like it is about to stall, but doesn't.. I don't have a Tach installed.. so I don't have any RPMs to tell.... however, I know that this idling is rougher than normal. Can a bad O2 sensor also cause the truck to hesitate? I may replace mine if I find it isn't a dirty EFI system causing it. Can anyone reccomend some kinda EFi cleaner I can put in in my driveway?

    http://billybob.coloradok5.com
    It's all fun 'n games, till someone gets stuck.
     

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