Uploaded April 2026 | Updated September 2026, 3 weeks ago

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In this video, we’re working through a misfire on a 2019 Hyundai Tucson using scan data, a brake torque test, a cylinder drop test, and some good old-fashioned swaptronics.

The scan tool gives us a direction, but the misfire counters aren’t consistent enough to be the whole answer by themselves. So the question becomes: can we prove the problem by moving parts around and watching what happens?

This is a simple but important misfire diagnostic path: don’t guess, don’t rely on one data point, and don’t let “swaptronics” turn into parts changing. Used correctly, it can be a valid test.


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00:00 - Shop plan and 2019 Hyundai Tucson misfire complaint
01:16 - Random misfire and cylinder 4 misfire codes
01:44 - Brake torque test and ignition misfire feel
02:00 - Watching misfire counters during the test drive
03:16 - Why misfire counters cannot always be relied on
04:02 - Diagnosing the misfire without secondary ignition scope data
04:39 - Cylinder drop test by unplugging coils
05:29 - Swapping spark plugs to see if the misfire moves
06:48 - Why intermittent misfires make swap testing harder
08:04 - Test drive after swapping plugs
08:40 - Misfire stays on cylinder 4 after plug swap
10:25 - Swapping ignition coils and retesting
10:49 - What an ignition misfire feels like under load
11:24 - Misfire moves to cylinder 1 after coil swap
13:28 - Confirming the bad coil and explaining the swaptronics path
14:37 - Is it safe to unplug coils with the engine running?
15:26 - Other ways to identify a constant misfire

⚠️ Disclaimer:
ScannerDanner LLC is not responsible for misuse, unauthorized changes, or incorrect application of any information provided. Always follow proper safety protocols when using tools, equipment, or procedures discussed in this video. Use this content at your own risk.