P0307 cylinder seven misfire?

1999 GMC SIERRA
200,000 MILES • AUTOMATIC
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HLENORI
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Replaced spark, plug and spark plug wire replaced coil and injector and PCV valve
May 5, 2026 at 3:08 PM
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HLENORI
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Also did compression check all cylinders about 120
May 5, 2026 at 4:27 PM
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HLENORI
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Any suggestions?
May 6, 2026 at 1:30 PM
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STRAILER
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Thanks for he detailed question, so can you confirm spark output for that coil? Here is a video to show you how to test it, keep your hands away.

https://www.youtube.com/watch?v=baq_aEWNQ0Y

If you have spark we can continue, also does the engine run okay and do you here a light ticking noise when the engine is cold? If so you may have a flat camshaft, you will still have good compression if the lobe is worn but you will still get this code. Please upload a short video in your response of the engine idling form under the hood, so I can see what's going on.
May 6, 2026 at 7:26 PM
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HLENORI
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Spark is good. It runs fine. No ticking.
May 6, 2026 at 8:46 PM
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STRAILER
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Thanks for the video, yep the engine is running good no noises, I would remove the spark plug to check on the condition and to see if there are any cracks, can you upload an images of the spark plug so I can see it? Also if anything checks out the only thing left is the fuel injector being partially clogged or one of the camshaft lobes is partially worn, but lets look at the spark plug first. Let me know what you find.
May 7, 2026 at 3:55 PM
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HLENORI
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New plugs and swapped around, no change. Swapped injectors, no change. Still on 7
May 7, 2026 at 3:59 PM
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STRAILER
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Okay, lets remove the valve cover, remove the fuel pump relay and then crank the engine over to check the intake and exhaust valve movement while comparing it to the other valves. Please send a video.
May 7, 2026 at 4:03 PM