Intermittent P0171 and p0300

Discussion in 'Engine & Drivetrain' started by chevy1500, Oct 25, 2018.

  1. chevy1500

    chevy1500 Member

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    hello guys i have a 07 tahoe LT non flex 5.3. And im having a issue diagnosing this lean issue i have on the left bank i changed the intake gasket checked coil packs and swapped out MAF sensors oh and i checked the compression and its good and the fuel psi was 45 with the key on engine off and I can see the needle bleeds off to about 30 psi but the truck starts right up oh and it has a slight rough idle im stomped
     
  2. Big Mama

    Big Mama Full Access Member

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    I think the psi should be around 60 but I’ll double check. The culprit could be the intake gasket you just changed only takes a little air to do that. Have you tried spraying some carb or intake cleaner while it’s running to check for idle pick up?
     
  3. chevy1500

    chevy1500 Member

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    Yes i done all that is possible and no change at all
     
  4. chevy1500

    chevy1500 Member

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    Also when i started up the truck the psi went to 60 psi and the needle was jumpy and when i rev it doesn't move and stays at 60 psi
     
  5. HiHoeSilver

    HiHoeSilver Away!

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    Your KOEO pressure is a touch low, but if you're 60 running, I'd look elsewhere first. Do you have a scanner to see the fuel trims?
     
  6. Big Mama

    Big Mama Full Access Member

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    It wouldn’t happen but there also may be an injector that’s a little clogged. The spray in cleaner may not do a lot but some seaform in the next few tanks might be an inexpensive way to see.
     
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  7. HiHoeSilver

    HiHoeSilver Away!

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    This is where I'm looking, too. If you can see your fuel trims and the short term comes down as you get on it, there's a vacuum leak somewhere. If the short term is getting worse as you raise rpm, you've got a fuel delivery issue (or a goofy MAF, but you said you checked that). Since your pressure seems reasonable, I'd clean the injectors.
     
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  8. chevy1500

    chevy1500 Member

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    I talked to a chev tech at the dealer and he said 45 psi with KOEO is pretty low it should be in between 50 and 60 and my truck only leans out when im driving so im still on it
     
  9. chevy1500

    chevy1500 Member

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    Changed fuel pump still rough idle and still getting the intermittent pending p0171 code then after i shut the engine off and turn truch back on the pending code is gone smh
     
  10. chevy1500

    chevy1500 Member

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    I looked at my short fuel trims this morning when i get on it it bank 2 shows higher than bank one
     

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