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Shudder/ miss at idle 5.7 vortec

Discussion in 'GM Powertrain' started by vicar75855, Sep 30, 2010.

  1. vicar75855

    vicar75855 Rockstar 100 Posts

    Well I got the heads rebuilt, new intake gaskets, new crank/ and cam sensors, belt, hoses, plugs, cap, wires, new FPR, lifters, and now I have a stange miss!

    I am not throwing any codes, I keep checking. The truck runs better than it ever has, gets up and goes from a start. Cruises at highway speeds no problem. The miss happens at idle, worse when I have my foot on the brake, but still happens at idle if in park. Its a regular even miss/ shudder.
    & it is driving me CRAZY!:grrrrrr:

    Any ideas what I should look at? No codes has me stumped as regular as it is and at idle I should have some code shouldn't I?
    As always much thanks for any and all help.
  2. silveradotrailblazer

    silveradotrailblazer Epic Member 5+ Years ROTM Winner 5000 Posts

    Have you scanned the transmission for codes? You need a scanner that reads trans codes.
  3. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    It sounds like you will want to take a look at the Distibutor end play, as well as the IAC.. since both of those can cause a miss at idle, also even with new wires after on drive they may have rubbed on something and the spark is arching out occasionally causing the miss..
  4. silveradotrailblazer

    silveradotrailblazer Epic Member 5+ Years ROTM Winner 5000 Posts

    murdog94 what would cause his shudder? Bad converter?
  5. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    Could be but im more looking at it from the stand point of a miss at idle and going from there.. Because the miss is present at idle in park. And once the actual miss is identified then if it is still shuddering i would look at the tranny. However i do agree that getting the tranny codes checked would also be a good idea.
    Also in response to the code at idle not necessarly it the sensors might not be detecting a problem even with consistency it might not be spaced close enough.
  6. vicar75855

    vicar75855 Rockstar 100 Posts

    I'll go take a look at the IAC, the end play on dist didn't seem bad to me at the time how much or little play should there be?

    Thanks for the replies guys, always a big help.
  7. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    Really shouldnt be any side to side play in the dist.. but a tinny bit really isnt bad. but a bad one will also make a lot of noise when you do try to move it.

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