He tapped the keyboard. "But look here. The firing voltage is normal. The burn time is short... but the coil oscillations are wrong."
: Technicians use the vertical (Voltage) and horizontal (Time) axes to verify if a signal meets specific manufacturer specs. Glitch & Noise Detection pdf automotive oscilloscopes waveform analysis
Diagnosis: A stretched timing chain (3ms of stretch). A scan tool would never show this. The PDF reference gave him the spec to compare against. He tapped the keyboard