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Idle speed fluctuations. Ideas??

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by yellco89, Mar 13, 2001.

  1. yellco89

    yellco89 Registered Member

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    Location:
    Arkansas
    When my Jimmy (89 5.7L TBI) is cold, the engine idles up great, but after it warms up it just barely idles at all. It never dies out or even surges, just idles very low. I have installed new O2 sensor and EGR valve to no avail. Would running without catalytic converter (dual exhaust) cause this?
     
  2. Chaz88K5

    Chaz88K5 1/2 ton status

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    Location:
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    I am having that same prob.....i installed a new motor (not because of that prob) and this one is doin the exact same thing as the old one....i did the same deal...but i changed every sensor on the motor and dident cange anything....if anyone has any ideas throw em our way.

    Chaz

    "Hondas look good under a k5's tires"
     
  3. mattman

    mattman 1/2 ton status

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    Well, don't know if this helps but here is what little I know. I have a 90 Jimmy that idles erratically. Idles good cold but when warm enough to go into closed loop then it goes to pot. It has something to do with when it enters closed loop (main control from O2) sensor versus open loop (main control temp sensor). My engine is so old that the idle would go all the way down like yours to the point I'd lose oil pressure. I shortened my cruise control linkage to prevent that and now it really is not happy. It could have something to do with vacuum level. Mine is very erratic at idle and by idle seems to track it. Know this might not help much, but maybe it will spark someone else.
     
  4. Triaged

    Triaged 1/2 ton status

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    I won't pretend to know your exact problem, but.....you mite want to check your EGR. Doesn't it open up when it goes into open loop? The only other thing I could think of would be the IAC (idle air control). I don't think that there is any way to adjust it only replace it :(

    '71 Blazer CST with alot of rust
     
  5. coopertwpk

    coopertwpk 1/2 ton status

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    Location:
    Spring Valley Lake Ca.
    adjusting Idle

    Ok here goes first replace your Idle air control valve ,next plug in wires to control valve ,keep ignition off go inside blazer jump upper left 2 terminals (as if to read codes ) turn on ignition ( do not start) go listen t IAC valve it will hum for about 30 sec now unplug IAC valve (this locks it at idle )now on the right side of throttle body their is a round cap O use a punch to remove it behind this their is a #10 torx .Ok now pull jumper terminal and start blazer turn the torx until desired rpm 800 is recomended ,turn off motor and plug in IAC valve.
    If this does not fix it or your Blazer idles to high the shaft has worn on the throttle body and brass sleeves need to be installed.

    88k5 silverado w4"lift soon to have <font color=orange>d44 and corp14ff</font color=orange> with 4.56s
     

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