2003 Pontiac Grand Am check engine light on, OBD2 reading code PO300 and bad smell coming from car

Tiny
CHRISHOLWELL
  • MEMBER
  • 2003 PONTIAC GRAND AM
  • 147,000 MILES
2003 pontiac grand am check engine light on, obd2 reading code PO300, and bad smell coming from car
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Friday, December 30th, 2011 AT 11:21 PM

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Tiny
CARADIODOC
  • EXPERT
You're going to have to describe the smell better than that. My best guess is you're smelling unburned gas because code 300 refers to a random cylinder misfire. The question now is whether too much fuel is going into the engine and the Computer is unable to correct it, or whether the computer is mistakenly commanding that much fuel.
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Friday, December 30th, 2011 AT 11:26 PM
Tiny
CHRISHOLWELL
  • MEMBER
Burning smell and pipe just past resonator is getting red hot
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Saturday, December 31st, 2011 AT 4:00 PM
Tiny
CARADIODOC
  • EXPERT
WAY too much raw fuel is going into the exhaust system. Driving it like that is going to destroy the catalytic converter. That is a real expensive repair. One thing you can check for yourself is for a leaking fuel pressure regulator if it is still located on the engine. Many have been moved to the gas tank. Pull the vacuum hose off and look for wetness inside. If there is any liquid fuel, the regulator is leaking and a lot of gas is going into the engine and out the exhaust. I've only heard of that once on a Chrysler product, but it's REAL common on GMs. If that is not the cause, you'll need a scanner that can display live data to see whether the Engine Computer is commanding the extra fuel in response to incorrect sensor information or whether it's trying to reduce fuel without success.

You can also connect a fuel pressure gauge to monitor what happens when you stop the engine. Pressure should hold for many days. If it drops off quickly, suspect an injector that isn't closing properly.
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Saturday, December 31st, 2011 AT 10:12 PM

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