5.3L miss question

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by Pikey, Nov 30, 2011.

  1. Pikey

    Pikey Moderator

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    Hi, I have a 2003 yukon with a 5.3L. I noticed that if I leave it in park and give it gas to get to between 900-1000 rpm, it runs alittle rough. I went to my buddy's house yesterday and he has a 2006 silverado with the same motor half the miles as mine. So we tried it with his. Same thing, idles smooth, runs fine in gear. But, when it is between 900-1000 it feels like it runs unbalanced. Anyone else notice this? If you don't mind, Try it on yours and let me know. Its not like it matters, it idles at 600rpm and when in gear it is always over the rough range. I was just curious if anyone else has the same issue, and if anyone knows what would cause it. Has new plugs, fuel and air filter, MAF was just cleaned, Throttle plate cleaned. I'm stumped.
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  2. murdog94

    murdog94 New Member

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    Which plugs are you running in it?? AC delco Platinums/Iridium plugs are all you want to run in the Vortec motors.
    And did you pull the the Throttle body to clean it or just do it with it on the motor. because if it was still on the motor you will want to pull it off and use a Throttle body cleaner on it. As to the rough idle.. come to think of it yeah, my 5.3s that i have had were a touch off but nothing really noticeable.
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  3. Pikey

    Pikey Moderator

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    I cleaned it on the truck. I only run the plugs indicated in my manual. Only AC delco not the NGK that they list. (I get them free). The roughness is hardly noticeable. I actually had to point it out to my friend as he did not even feel it. At idle it runs perfectly smooth, it just gets rough between 900-1000 rpm. Most people would probably never notice it.
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  4. murdog94

    murdog94 New Member

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    Yeah it may just be a fault with the TBI motor not wanting to adjust the trim properly, since as i said with my 5.3Ls that i have owned i had noticed a bit to but never really thought much of it since well, as you say it isnt really noticeable..
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