CAR IDLES REALLY ROUGH AT START UP UNTIL WARMED UP

  • Tiny
  • Grandamkc
  • 1999 Pontiac Grand Am
  • 113,000 miles

My 99 grand am runs really rough until it warms up and then is fine. Lately when I start it, it sputters and dies. If I punch the gas quickly it comes to life. There is a fuel smell with the exhaust. I have unplugged the maf sensor and there is no change and it is clean. Egr valve seems to be ok and the passages are not blocked. I have sprayed all over with carb cleaner and haven't found any vacuum leaks. I'm at a loss! It's the 3400 engine.

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Saturday, November 9th, 2013 AT 5:43 AM

6 Replies

  • Tiny
  • Wrenchtech
  • Expert
  • 20,028 posts

Pull the vacuum line off the fuel pressure regulator with the engine running and see if any fuel comes out of the regulator port.

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Saturday, November 9th, 2013 AT 6:06 AM
  • Tiny
  • Grandamkc
  • Member

Pulled the vacuum line from regulator and ran for five minutes. No fuel coming out

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Saturday, November 9th, 2013 AT 7:08 AM
  • Tiny
  • Wrenchtech
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  • 20,028 posts

OK, that means it's good. You are going to need a high end scan tool to analyze the sensor data when this is happening to paint a picture of what is happening inside the engine before you can determine why it's happening.

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Saturday, November 9th, 2013 AT 7:23 AM
  • Tiny
  • Grandamkc
  • Member

Ok this time it threw another code. A po0133 for 02 sensor bank 1. Any ideas?

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Saturday, November 9th, 2013 AT 7:26 AM
  • Tiny
  • Wrenchtech
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  • 20,028 posts

That slow response in that sensor and it should be replaced but I expect you have more problems than that.

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Saturday, November 9th, 2013 AT 7:29 AM
  • Tiny
  • Grandamkc
  • Member

Got it fixed! Put a match in the gas tank and now no more problem! Lol

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Saturday, November 9th, 2013 AT 7:49 AM

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