Engine light stays on, code Po308

2006 JEEP COMMANDER
180,000 MILES • 4.7L • V8 • 4WD • AUTOMATIC
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SHIRLEYS
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I had a code po308 I changed the coil pack and put a new spark plug in the gap was way off on the old one. I tried to reset the engine light with OBD reader but when you drive it, it comes back on I put OBD reader back on it shows no codes.
Dec 14, 2021 at 1:36 PM
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ASEMASTER6371
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Good evening,

The first thing I would do is a compression test on cylinder 8 to be sure there is compression for the cylinder to work.

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

These engines have a habit of burning exhaust valves. You can rent a tester at a parts store for this test.

You need 140-160 pounds.

Roy
Dec 14, 2021 at 2:53 PM