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silverado 5.3 problems

Discussion in 'Truck & Equipment Repair' started by k-20 work horse, Dec 2, 2007.

  1. k-20 work horse

    k-20 work horse Member
    Messages: 35

    My dad has a 99 silverado 1500 2wd w/a 5.3l vortec. it has a bad surge at idle like 400-450 rpm's it has a fairly new fuel pump and filter and i replaced the mass aiflow tonite but problem not solved any ideas would be great guys thanks alot
  2. elshauno

    elshauno Member
    Messages: 32

    Maybe a vacuum problem?
  3. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    A couple common things on the 5.3's that will cause this...

    First is a dirty throttle body. A thorough cleaning of the throttle body will fix many idle problems on the 5.3's. To do it right you need to remove it and clean on the back side of the throttle plate and also remove the idle air control motor from it and clean it and the air bypass port through it.

    Is the check engine light on?

    Two other things that will usually kick the CEL on is a sticking EGR valve or a leaking intake gasket (especially on the 4.8's and 5.3's)

    A failing EGR will usually give you a CEL pretty fast, but leaking intake gaskets can take a while before it will recognize a problem so it won't always kick it on right away..