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  1. #1

    Default Newbie here. Hi everyone. 1991 5.7 4x4 1500

    What a great forum. Been reading for a while now.I have a quick question. My truck
    idles a little rough. Smooths out as soon as I start accelerating. Runs great then.
    Someone mentioned the EGR valve. Haven't had time yet to check it out. It's been
    really cold the last couple days. Any ideas would be appreciated. Thanks a bunch.

  2. #2
    Master Mechanic BurbanMan's Avatar
    Join Date
    Jul 2013
    Location
    Dolores, CO
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    790

    Default

    Quote Originally Posted by jbopeep View Post
    What a great forum. Been reading for a while now.I have a quick question. My truck idles a little rough. Smooths out as soon as I start accelerating. Runs great then. Someone mentioned the EGR valve. Haven't had time yet to check it out. It's been really cold the last couple days. Any ideas would be appreciated. Thanks a bunch.
    Have you done a basic tune up? I.e. Plugs wires cap rotor and fuel filter? This info would help us a lot to narrow down possible suspects. You can take the egr valve off and clean it good. You can also clean the o2 sensors with acetone and a clean red shop rag
    Chuckie!!!


  3. #3

    Default

    I'm sorry. I'm new at this. Plugs, cap and rotor and fuel filter have been replaced.
    I'll check the EGR and 02 sensor as you suggest. Thanks a lot.

  4. #4
    Master Mechanic BurbanMan's Avatar
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    Default

    Quote Originally Posted by jbopeep View Post
    I'm sorry. I'm new at this. Plugs, cap and rotor and fuel filter have been replaced. I'll check the EGR and 02 sensor as you suggest. Thanks a lot.
    changing the wires would probably help too
    Chuckie!!!


  5. #5

    Default

    The wires are only about a year old. But I'll check
    them anyway.

    If a wire is bad, wouldn't it miss while ccelerating also?

  6. #6
    Sr. Apprentice
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    Jan 2014
    Location
    Fort Drum, NY
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    36

    Default

    Welcome to the forum...Sometimes. But with increase in rpms you would not notice it. Not to mention sometimes wires fail because your not getting enough power put throigh them, and with that every second or third fire could 'jump' the short and fire at that time. Does it idle rough even on choke starts (first cold start before it warms up)? I have an 88 and after changing the O2 sensor it ran fine, still pops a code every now and again though, probably because my cat, egr, and air pump delete. Not a hard code though, so can't read it after I shut the truck off.
    89 V1500 Suburban

  7. #7

    Default

    Yes it does. It idles rough when It first starts but just idles faster. Where is the 02 sensor located and how difficult is it to change? Thank you for taking the
    time to help me out.

  8. #8
    Sr. Apprentice
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    Jan 2014
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    Fort Drum, NY
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    Default

    It is on the drivers side exhaust manifold. Not difficult to change. But having an O2 socket helps alot. Not alot of room in there for a wrench. Maybe get a 1/6 of a turn at a time. Get the Bosch sensor and just splice in the wire to the old connector, cheaper than paying an extra $20 for the connector already on it. Let me know if it fixes the problem.
    89 V1500 Suburban

  9. #9

    Default

    Thanks. I will let you know.
    91 Suburban 5.7 1500 4wd

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