Check the two main symmetry axes: spark and fuel. 1. Run a compression test on all cylinders – a misfire will show a lower number on that spot and will break the symmetry of the peak pattern. 2. With a timing light, watch the spark angle at idle and at a steady speed; a drift on one cylinder will appear as a phase shift that breaks the even pattern. 3. Use a fuel injector pulse test; inject a single cylinder while the others are blocked, then look for a missing pulse or an irregular shape – that will show up as a “hole” in the otherwise uniform pulse stream. 4. Verify the MAP and O2 sensors; a phantom misfire can stem from a sensor that is reading the same on the other cylinders but slightly off on the culprit, again breaking symmetry. 5. Finally, if all the above are clean, perform a spark plug pull‑back test – a plug that returns with a different residue pattern than the others indicates a localized head issue. Stick to the evenness of readings; the odd one out is your culprit.

Exactly, lock the timing, lock the injector. Anything that shifts one axis breaks the pattern. Keep the steps in order and you’ll see the outlier before the engine spins a new mystery.