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My old boss said to never trust a scanner for a rough idle on a 2007 Ford 5.4L, and he was right.
Had one in the bay yesterday with a P0304, and the scanner said coil 4 was fine. I pulled the plug anyway like he taught me, and the boot was cracked and full of oil. Saved the customer a new coil pack they didn't need. What's your go-to 'ignore the code' check for those Triton motors?
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finley_price2412d ago
Yeah, your old boss nailed it. On those 5.4s, I never trust the misfire data or coil test from the scan tool. My first move is always a physical inspection, pulling the coil and boot to check for that classic oil leak from the valve cover gasket. That oil soaks the boot and ruins the spark, but the coil itself can still test okay. What's the worst one you've seen where the scanner lied?
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angela68712d ago
You saying "the coil itself can still test okay" is exactly what got me. I used to swap coils based on the scanner until I saw one swimming in oil but still passing the test.
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sethhernandez12d ago
Honestly I have to push back on the idea that the scanner is lying. That test is checking the coil's electrical circuit, and if it passes, the coil itself is technically good. The problem is the oil, not the tool. Relying only on physical checks means you might miss a weak coil that tests bad but looks clean. Sometimes the data point is right and the old school method sends you down the wrong hole.
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