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Discussion Starter · #1 · (Edited)
It has recently come to my attention that certain Polaris vehicles with claimed Capacitive Discharge Ignition (CDI) actually has Electronically Controlled Inductive Discharge Ignition (ECM or ECU unit).

From Wikipedia:
As ignition technology developed, engineers realized that a functional ignition system could be designed that dispensed with the magnets altogether (prior reference to magnetos). By applying a current to a primary wire loop wrapped around an iron magnetic core, a magnetic field would be generated in the primary loop without the magnets. This magnetic field would induce a current in an adjacent longer secondary loop of wire. By opening the circuit in the primary loop, the collapsing magnetic field would cause a voltage to be induced in the secondary loop. This high voltage was carried...... (description shortened) to the spark plugs in a gasoline car or truck engine.

The most familiar version of this kind of system was invented by Charles F. Kettering in about 1909 and was known by some as the Delco ignition system. Later patent applications to the US Patent Office make reference to the "Kettering ignition system". This type of ignition system was used on automobiles, trucks, lawn mowers, tractors, chainsaws, and other gasoline-powered machinery with great success for many decades until the development of capacitive-discharge ignition systems.

Also from Wikipedia:
A typical CDI module consists of a small transformer, a charging circuit, a triggering circuit and a main capacitor. First, the system voltage is raised up to 250 to 600 volts by a power supply inside the CDI module. Then, the electric current flows to the charging circuit and charges the capacitor. The rectifier inside the charging circuit prevents capacitor discharge before the moment of ignition. When the triggering circuit receives the triggering signal, the triggering circuit stops the operation of the charging circuit, allowing the capacitor to discharge its output rapidly to the low inductance ignition coil. In a CD ignition, the ignition coil acts as a pulse transformer rather than an energy storage medium as it does in an inductive system. The voltage output to the spark plugs is highly dependent on the design of the CD ignition. Voltages exceeding the insulation capabilities of existing ignition components can lead to early failure of those components. Most CD ignitions are made to give very high output voltages but this is not always beneficial. When there is no triggering signal the charging circuit is re-connected to charge the capacitor.

The CDI referenced in some models of Polaris is controlled by the ECU (electronic control unit). The ECU is an electronic switch which stops the flow of current in an inductive discharge ignition system.

Copied from the Polaris service manual 9922239:
The Sportsman has incorporated into it's design a DC/ CDI ignition system. The DC/ ignition system relies on battery power for ignition.

EFI - Instead of generating DC voltage via flywheel magnetic induction, a 12 Vdc current is supplied from the Ignition/Fuel Pump Relay to the Ignition coil. At the ECU, a small A/C signal from the CPS helps the ECU pre-determine Top Dead Center (TDC), which in turn signals the ECU to release the electrical charge collapsing the coil field for ignition (based on the ECU timing map).

CDI- A 12 volt DC current is supplied directly from the battery to the CDI. At the CDI, a DC current is supplied to the coil for the initial ignition charge. A small A/C signal from the stator pulse coil triggers the CDI to fire the coil.

DC/ignition systems have the ability to ignite with as little as 6 volts of power.

Some of the advantages of DC ignition are:
• Stronger, more consistent spark at low rpm for better performance
• Easier starts
• Fault detection by the ECU (EFI)

From Wikipedia:
Some electronic ignition systems exist that are not CDI. These systems use a transistor to switch the charging current to the (spark generating) coil off and on at the appropriate times. This eliminated the problem of burned and worn points, and provided a hotter spark because of the faster voltage rise and collapse time in the ignition coil.

From this definition, the 'CDI' of some Polaris models is not CDI, but Electronic Controlled Ignition.

Knowing this makes troubleshooting the ignition system in question easier.

Disclaimer: I do not attribute Wikipedia as an absolute source of information, but the information gleaned and published here is parallel to the teachings that I received about the subject.
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