Ignition / Engine Noise

Symptom: Popping, ticking, or clicking noise. Rate matches engine RPM or ignition cycle. Not a tone — more erratic than alternator whine.

Root cause: Electromagnetic interference from spark plug firing, ignition coil switching, or injector pulses radiating onto signal cables.

Diagnostic steps:

Step 1: Confirm RPM correlation Rev engine while listening. If noise frequency changes with RPM and sounds like ticking/popping rather than a tone: ignition noise.

Step 2: Check RCA routing RCA cables near ignition components (coil, spark plug wires, ECU)? Route to opposite side.

Step 3: Inspect spark plug wires Resistor plug wires required. Measure resistance of each wire — should be 1,000–3,000 Ω/foot. Zero or infinite: replace.

Fix sequence:

1. Re-route RCA cables away from engine bay and ignition components
2. Replace spark plug wires with suppressed/resistor type
3. Add ferrite cores to RCA cables (clip-on, near amplifier end)
4. Add inline capacitor (0.1–1 μF) on power antenna lead (older vehicles)
5. Check for missing or damaged engine-to-chassis ground strap