Choose Your Primary Ignition System Help Topic Below
So, The primary ignition system consists of:
- The battery
- Ignition switch
- The resistor
- Ignition module
- Contact points
- Coil primary wiring
So, the primary ignition system voltage is low; operating on the battery`s 12 volts. And, when the ignition is on; a low voltage current flows; from the battery through the primary windings of the coil. Next, through the breaker points and back to the battery. Consequently, this current flow causes a; magnetic field to form around the coil.
So, how long the primary coil is turned ON is called Dwell. Once the maximum current is reached; the coil will be at its maximum power potential (strongest magnetic field). This is called coil saturation.
Consequently, short Dwell times will not give enough time for the coil to; become saturated causing a weak spark. In contrast, dwell times that are too long; will not increase the magnetic field. But, it will raise the temperature in the coil windings.
So, an ignition system must turn on the primary coil; long enough to reach maximum power. But, not so long as to overheat the coil. So, modern systems use a power transistor; to turn ON and OFF the primary coil windings. Consequently, this transistor is part of the Ignition Control Module.
Proper dwell and timing, require sensors that monitor:
- Engine (RPM)
- Crankshaft and/or Camshaft Position
- Engine load
- Engine temperature
- And, Include a Knock Sensor
So, most engines use a Crankshaft Position Sensor (CKP) to monitor (RPM); and indicate which pistons are going up or down. Also, camshaft Position sensors (CMP); will indicate if the piston is on compression or exhaust. Consequently, it monitors engine (RPM). Manifold Absolute Pressure (MAP) sensors in combination with; Throttle Position sensors (TPS) will monitor engine load. However, most vehicles use Mass Airflow sensors (MAF) to monitor engine load.
When calculating spark timing; the Engine Coolant Temperature (ECT) and Intake Air Temperature (IAT) are used as well. Finally, most systems use a Knock Sensor (KS). The knock sensor is a feedback sensor. So, engine (RPM); Load and Temperature; are all used to calculate the Ignition timing. When timing is advanced the cylinder will knock or ping. When a ping or knock occurs the knock sensor signal; will retard the timing until the knock goes away.
Types Of Ignition Systems Include:
- Distributor Ignition System
- Direct Ignition System (DI)
- Coil-on-Plug (COP); Individual coil for each cylinder.
- Individual coil for each cylinder with separate HT (high tension) leads.
- DIS-Wasted Spark Ignition, separate coil for each two cylinders.
- Synchronous ignition with two secondary winding coil terminals.
Possible reasons for failure of the primary ignition circuit:
- No supply voltage to the ignition coil.
- Broken insulation between the coil’s primary and the secondary windings
- Bad ignition coil.
Thank You !