Check Engine Light on with codes P0300, P0302, and P0303?

2005 FORD EXPEDITION
200,000 MILES • 5.4L • V8 • 4WD • AUTOMATIC
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OREO101
  • MEMBER
  • 103 POSTS
Hi,

My car is due for inspection in PA.
I get codes P0300, P0302 and P0303.
Showing misfires.
I will replace spark plugs and coil packs for #2 and #3 cylinders.
I did the other plugs and coil packs for other cylinders.
Luckily the plugs have been replaced before, so the plugs are 1 piece and not the dreaded original 2-piece that had possibility of breaking off in cylinder.
Could there be other causes for these CEL codes?

Thanks!
Mar 24, 2024 at 8:08 PM
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BORIS K
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 836 POSTS
Hello,

The most common causes for misfire on these 5.4 3V engines are spark plugs and coils.

https://www.2carpros.com/articles/how-to-check-for-ignition-spark
and
https://www.2carpros.com/articles/how-to-test-an-ignition-system

A few other causes can be injector malfunction and intake air leaks.

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

https://www.2carpros.com/articles/engine-misfires-or-runs-rough
and
https://www.2carpros.com/articles/automotive-engine-misfire-code-p0300-causes-and-solutions

Hope this helps.

Cheers, Boris
Mar 25, 2024 at 5:35 AM
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OREO101
  • MEMBER
  • 103 POSTS
Yes, it does!
Thanks!
Mar 25, 2024 at 11:36 AM
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BORIS K
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 836 POSTS
Thank you for using 2CarPros.

Please let us know if we can assist with anything else car related.

Cheers, Boris
Mar 26, 2024 at 6:52 AM