still sounds like it has a fouled plug?

2003 CHEVROLET BLAZER

129,231 MILES • 6 CYL • 4WD • AUTOMATIC

MIKEDELORENZO83

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Had a fouled plug or two on my blazer. 4.3 liter. Changed them. Runs a little better but still sounds like it has a fouled plug. Better then it was but still sounds crappy. What can it be? Injector? I also started running premium gas in it. Can that have anything to do with fouling plugs?

Dec 28, 2010 at 7:44 PM

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SQM

AUTOMOTIVE REPAIR CONTRIBUTOR
6,383 POSTS

Hello,

Typically when the engine misfires, it will produce fault code and the engine light will be illuminated.
Is the check engine light on?

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Keep in mind that a spark plug can misfire due to a faulty coil pack. Sometimes when you have an issue with the coil pack it will produce random misfires.

Here is a helpful guide:

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

Also using premium gas will not trigger misfire.

I have attached diagrams for your reference.

Please let me know of any questions.
Thank you.

Images (Click to enlarge)

Sep 4, 2021 at 12:27 PM