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Idle Issues

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by trivers, Nov 10, 2007.

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  1. trivers

    trivers New Member

    Just want to know what you guys think the most common/first place to look would be. I have a 1993 K1500 Burb. It idles great when you first start it, but after driving for a while then driving around the parking lot when you let off the gas the idle will drop like it is going to die (it never does completely die) then comes right up where it should.

    From what I hear it could be, EGR Valve, MAP Sensor, Fuel Filter, or Fuel Pump. I don't mind replacing them all, but am trying to save a little money this month and need to take it on a little trip for Thanksgiving. So replacing the culprit the first try would be nice.


    TIA

    I am hoping its NOT the fuel pump :grrrrrr: DON'T want to drop the tank!!!
  2. Crawdaddy

    Crawdaddy Moderator Staff Member Platinum Contributor 1000 Posts 100 Posts

    The most common issue with bad idleing around here is vacumm issues, so you can start there. Unplugged frquently reccomends using a can of starter fluid and spraying starter fluid on different potential culprits. If the idle runs up when you hit a certain spot, you found it. Beware, using this method could potentially be dangerous, so be careful.
  3. Cableguy

    Cableguy New Member 1000 Posts 100 Posts

    I would kinda doubt the fuel pump but fuel filter is a possiblity. Crawdaddy is right its probably vacumn leak. Good luck
  4. trivers

    trivers New Member

    Not a vacuum leak tried that and nothing. Might try it again after it warms up more.
  5. unplugged

    unplugged New Member 1000 Posts 100 Posts

    How does the performance differ between neutral and drive? Could be something as simple as a bad plug or plug wires. I recently picked up an intermittent stumbling idle after some recent work. It idles rough in gear and smooths out in neutral. I'm thinking I have to go back over the plug change I just did, but haven't had the time.[​IMG]
  6. trivers

    trivers New Member

    I just replaced the wires, plugs, cap, and rotor. It did the same before and after. I am starting to think it is the fuel filter.
  7. trivers

    trivers New Member

    Any new ideas? So far plugs, wires, cap, rotor, o2 sensor, fuel filter, and oil change. Still the same thing it will drop to like 100 rpm and idle all rough.
  8. homer911

    homer911 New Member 100 Posts

    You might want to try unpluging the IAC and MAP sensers when it is running rough. if theres a change in the idle u have most likely found your problem. It should kick in to default mode if u unplug either one for a short time.
  9. collinsperformance

    collinsperformance New Member 100 Posts

    not to be an a$$ but have you checked the computer for codes? that be a good start. i just got a truck that a mechanic of 35 years told the customer the head gasket was junk and he wanted $2000 to fix it so they dumped the truck to me for free. i started it and the cat went to bright red on the pass side and it was boiling the heater hoses. i put the code reader on it and the ignition moduel failed it test. i replaced and all was good and i tried to give it back to the owner but they said it is yours and it is now going to the Youth group of our church for money for the group. sometime the computer will tell you wat is wrong (some times it does not but a good starting point)....mike
  10. trivers

    trivers New Member

    Nope already tried it flashes 12 for no codes

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