Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Ignition System Description
The J20B engine uses an electronic ignition system that has neither distributor nor high-tension cords. It consists of the following:
- ECMÂ
ECM monitors engine and vehicle conditions through the signals from the relevant sensors, determines the most suitable ignition timing and sends correct signals to ignition coil assemblies.
- Ignition coil assembliesÂ
The ignition coil assembly is a combination of an ignitor and ignition coils. It is provided for each cylinder and the ignition coils fit directly over each spark plug. The current to the primary coil is turned on and off according to the signal from the ECM. When the current flowing through the primary coil is broken, a high voltage is induced in the secondary coil. The high voltage is applied directly to the spark plug of each cylinder.
- Spark plugsÂ
- CMP (camshaft position) sensor and CKP (crankshaft position) sensorÂ
Using signals from these sensors, ECM identifies a specific cylinder whose piston is in the compression stroke, defects the crank angle and adjusts the initial ignition timing automatically.
- TP (throttle position) sensor, ECT (engine coolant temperature) sensor, MAF (mass air flow) sensor, IAT (intake air temperature) sensor, knock sensor and other sensors/switchesÂ
ECM controls the ignition timing also using signals from these sensors/switches in addition to signals from the CMP and CKP sensors.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.