Several technicians attempted to diagnose and fix the issue, but the problem only became apparent when the engine ECU reached a certain temperature inside the engine bay.

Many suspected faulty ignition components and tried replacing the ignition coils and spark plugs, while others blamed the wiring. However, none of these solutions resolved the issue.

The misfire was always isolated to the 5th cylinder. After confirming that compression was within spec across all cylinders, I decided to take a deeper look. Using my oscilloscope, I analyzed the output stage of the engine ECU and discovered a failing ignition MOSFET.

After replacing the faulty MOSFET, the struggling M54B30 was restored to its former glory, running smoothly once again.