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Code p300 random misfire

Tiny
SAMGREW
  • MEMBER
  • 2003 CHEVROLET MONTE CARLO
  • 3.1L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 140,000 MILES
Car surging with misfire.
Wednesday, April 11th, 2018 AT 3:19 PM

6 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good evening.

How old are the ignition components?

The most common cause for this code is low fuel pressure. Do you have a tester to check the fuel pressure?

Roy
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Wednesday, April 11th, 2018 AT 3:31 PM
Tiny
RENEE L
  • ADMIN
  • 1,257 POSTS
Hello SAMGREW,

Thank you for visiting 2CarPros. Here is a link to an article from this site with step by step instructions and pictures explaining the process of checking the fuel system pressure, regulator and fuel pump in less than fifteen minutes:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

If you need further assistance please come back to the site we are always happy to help.

Kindest regards,

Renee
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Wednesday, April 11th, 2018 AT 5:05 PM
Tiny
SAMGREW
  • MEMBER
  • 36 POSTS
Furl pressure is between 52 to 57 psi. Engine skips at idle and at high engine rpm engine surges.
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Thursday, April 12th, 2018 AT 12:27 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Okay, that reading is good.

Try disconnecting the EGR valve electrical connector and drive it and see if it continues.

Roy
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Thursday, April 12th, 2018 AT 1:19 PM
Tiny
SAMGREW
  • MEMBER
  • 36 POSTS
Disconnected EGR electrical connector. No change.
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Friday, April 13th, 2018 AT 6:38 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Okay not the EGR. I would also check the catalytic converter. An easy way to check is to remove one of the upstream O2 sensors and drive it and see if it changes. That will check for partial restriction in the converter.

Roy
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Friday, April 13th, 2018 AT 7:17 AM

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