95 Silverado idles slow (too SLOW) 600 rpms! help

Discussion in 'Chevy C/K Truck Forum' started by jteuban, Oct 5, 2011.

  1. jteuban

    jteuban New Member

    Hello, I am having diffuculty with my trucks idle. Its a 95 SIlverado, it only idles at about 600 rpms all the time. It does not stall like this but it concerns me. It has been chiped and I am currently only running 93 oct. It is also TBI. What could the problem be, I have troubleshooted and I am coming up with nothing. Could it be the throttle pos sensor or the idle pos sensor. I just cant understand what would cause this. Can I manually adjust the idle myself. Its not a vortec.
  2. silveradotrailblazer

    silveradotrailblazer Epic Member 5+ Years ROTM Winner 5000 Posts

    Have you cleaned the throttlebody and IAC lately? I like to remove the throttlebody so I can clean the bottom and top with a soft toothbrush and throttlebody cleaner. Also take off the IAC valve that is mounted in the t/body side and clean the pintle with the cleaner. This pintle moves in and out to control the idle. It gets carboned/gummed up and can't move freeely in and out to control the idle.
  3. jteuban

    jteuban New Member

    No I have not cleaned it latley. It is always at like 600 if ur in drive and its real annoying. It cold starts and idles right but once it gets to working temp it comes down to 600-650. It also has a prob above idle like at 800 rpm if ur going real slow it likes to surge. could this be a dirty TB. CAN I ADJUST IT?
  4. silveradotrailblazer

    silveradotrailblazer Epic Member 5+ Years ROTM Winner 5000 Posts

    I would start with a good throttlebody cleaning. If you haven't done this in awhile its not going to hurt. Don't use carb cleaner!
  5. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    You shouldn't need to adjust it. As mentioned, give the TB a good cleaning with some TB cleaner and a toothbrush. Remove the IACV so you can clean the port thoroughly. Slow idles is not a common problem on these trucks, fast idle is....

    Is 600 in gear, foot on brake?
  6. jteuban

    jteuban New Member

    yup, in gear with brake applied. I will try this. Also could the TPS have something to do with this, it has been surging. sometimes at stop signs it acts funny and drops rpms just a little and then catches itself and comes back to idle. only 1 time this happened and I got some trottle body cleaner and sprayed around the trottle plate and it never happened again. Also a few weeks ago I got a check engine light and the idle was normal so I shut the truck down and started it back and it went away and its back low again. Any more ideas??
  7. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    Check the Codes for the CEL. 600 in gear with the brake on is actually pretty close to normal since the tachs in those trucks werent most accurate anyway. when was the last time you did a full tune up? Plugs wires cap rotor all that jazz? and what do you mean it is chipped what kind etc? And no you cannot adjust the idle even if you wanted to the PCM controls the idle thru the IAC, and when all is normal the idle will be just fine.
  8. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    Get a fresh TB base gasket. Those are prone to failure - That might be causing surging.
  9. Caddiac

    Caddiac Epic Member 5+ Years 1000 Posts

    If the only trouble is the low idle don't sweat it, 650 is normal idle speed. The advice you have received so far is sound and should be considered as routine preventative maintenance regardless of whether or not you are having a problem.

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