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Rough Idle

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KASS, Mar 8, 2000.

  1. KASS

    KASS Registered Member

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    I purchased a 88 Blazer with a 350 TBI engine in November 99, after fixing the thermostat I have noticed that when the engine is warm that the idle fluctuates in the nieghborhood of 400-800rpm. Before the engine never reached a normal operating temp. because of the thermostat being stuck open. I have run some injector cleaner though and did not notice any change in the idle. I have heard there is such a thing as a idle selinoid which might be my problem, but at the parts store they were not sure exactly what I was referring too. Is this a likely culprit, if so what is the exact name and location on the engine?
    Thanks
     
  2. Eric77

    Eric77 Registered Member

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    could be the throttle position sensor. It should be located on the end of the throttle shaft. Your computer determines fuel delivery based on the throttle valve angle or driver demand. It does this by monitoring the output voltage from the throttle position sensor. A broken or loose TPS can cause intermittent bursts of fuel from the injector and cause an unstable idle because the computer thinks the throttle is moving. That's what my Haynes manual says. If you have the codes read, that will tell you. should be a code 21 or 22. Good luck!!
     
  3. Brian 89KBlazer

    Brian 89KBlazer 1/2 ton status

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    I'd try simple things first like vaccuum lines and hoses. If there are no leaks there, I would try testing the MAP sensor. I'll have a look in my Factory service manual and Haynes manual tonight to see what else I can find.

    Good Luck
    Brian
    Still in search of the TBI KING!!
     

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