Code P0300 and engine running rough after replacing the timing chain?

Tiny
CASEY0714
  • MEMBER
  • 2007 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 200,000 MILES
I just replaced the timing chain on my truck listed above after replacing the timing chain. I now have a fault code P0300. I’m pretty sure that I installed everything correctly. But now I have the fault codes, and the engine is running very rough. Is it possible that the timing marks are not lined up correctly and maybe be off by a tooth?
Tuesday, March 4th, 2025 AT 10:02 AM

6 Replies

Tiny
CASEY0714
  • MEMBER
  • 4 POSTS
I also replaced the plugs and plug wires. And I checked all of the grounds. I cleaned my throttle body, and I cleaned the mass airflow sensor.
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Tuesday, March 4th, 2025 AT 10:17 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,453 POSTS
Yes, if you are off a tooth on the timing chain it will not run correctly. Here is a video of the job being done so you can compare what you did to see if it is correct:

https://youtu.be/mrp9YXPaYFg?si=p0yGPJJ2jmkl61BC

Please check the image below as well, Also, this can be a vacuum leak so I would go over this guide as well:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Check out the images (below). Please let us know what happens.
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Tuesday, March 4th, 2025 AT 1:57 PM
Tiny
CASEY0714
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Thank you for the reply. I pulled the timing cover and checked. I was a tooth off. I got it lined up correctly. I also replaced all 8 coil packs. I am still getting the P0300 code, and the engine is running rough. Any suggestions on what to check next?
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Tuesday, March 11th, 2025 AT 9:04 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,453 POSTS
Lets do a compression test to see if the engine is in good shape with no bent valves. You can rent a compression gauge for free at the auto parts store FYI.

https://www.2carpros.com/articles/how-to-test-engine-compression

Please go over this guide and get back to us.
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Tuesday, March 11th, 2025 AT 12:42 PM
Tiny
CASEY0714
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Thank you for your support. I will do the compression test. I have a compression gauge. I will let you know what happens. Again, thank you so much.
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Tuesday, March 11th, 2025 AT 1:35 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,453 POSTS
Np, we like helping people :)
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Wednesday, March 12th, 2025 AT 9:53 AM

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