Connect crankshaft-speed variation, cylinder contribution, ignition, fuel, and mechanical evidence.
Explain why crankshaft-speed changes can indicate a misfire; compare misfire counters across cylinders and conditions; distinguish ignition, fuel, and mechanical causes; choose a confirming test rather than replacing a part from a code alone.
Conceptual four-cylinder teaching model. Misfire counters, relative contribution, waveform shapes, and fault responses are illustrative—not OEM data or definitive diagnostic criteria. Real detection depends on operating conditions, ECM strategy, and vehicle-specific service information. A flashing malfunction indicator lamp may indicate a catalyst-damaging misfire; avoid continued driving and follow manufacturer guidance.
The CKP disturbance scenario illustrates that an irregular speed signal may complicate misfire interpretation. It does not imply that every CKP fault sets a misfire code.
Each pulse represents the crankshaft acceleration contribution after a combustion event in firing order 1–3–4–2. A weak event may produce a smaller speed increase; other disturbances can affect the signal.