Timing issue?

Discussion in 'GM Powertrain' started by BurbanMan, Jan 29, 2014.

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  1. BurbanMan

    BurbanMan Member 100 Posts

    I recently replaced the intake gaskets on my wife's 99 Tahoe (5.7/auto). After doing so I had a reputable shop set the timing since I don't have that fancy computer. Now 3 days or so later the "service engine soon" light comes on. The truck feels like it has not low end guys at times. This sounds like timing issue to me, but I would like a second, third, or 100th opinion lol Here are the codes that we pulled: p0420/p0430. I've read that these are generally O2 sensor or cat converter issues, but again I would appreciate confirmation from those of you more knowledgeable than myself. Thanks in advance!

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  2. BurbanMan

    BurbanMan Member 100 Posts

    Dang. Nobody has any ideas?
  3. dpeter

    dpeter New Member 100 Posts

    Intake leaking?
  4. BurbanMan

    BurbanMan Member 100 Posts

    no coolant in the oil or vice versa, and I haven't spotted any fluid seeping. I've been keeping a pretty close tab on it for about a week
  5. Conlan Rose

    Conlan Rose Super Moderator 1000 Posts 100 Posts

    Before the intake replacement was there oil or coolant getting in the the cylinders? Either burning can quickly damage the Cat or the O2 sensors. My Tahoe has that code because of a bad cat which I'm replacing in June.
  6. Pikey

    Pikey Moderator Staff Member 1000 Posts 100 Posts

    Just for the heck of it I would take a can of carb cleaner and spray around the intake while it was running listening for rpm increases.
  7. BurbanMan

    BurbanMan Member 100 Posts

    Yes, there was coolant in the oil

    I'll give it a try

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