Diagnosing a P0304 Misfire Only Present at Idle: 2010 Hyundai Accent

Today we have a 2010 Hyundai Accent that has a bunch of DTC's stored as well as a cylinder 4 misfire at idle only. P0300, P0301, P0302, P0303, P0304 The car has already had coils and plugs replaced by the customer which did not resolve the issue. We walk through the standard misfire diagnostics and discover that the intake manifold gasket was torn. After replacement, the vehicle ran fine and it appears that the gasket was damaged from some previous repair or repair attempt. This did not resolve all of the DTC issues, but the customer just wanted the vehicle to run okay and was not concerned about the check engine light.

Timecodes
0:00 - Intro
0:26 - Symptoms/Data
3:13 - Relative Compression
4:20 - Injector/Ignition Waveforms
5:53 - Vacuum Leak Test with Scan Tool and Brake Clean
6:56 - Smoke Test Intake
7:47 - Outro