There are two basic methods of detecting IGF. Early systems used the Counter Electromotive Force (CEMF) created in the primary coil and circuit for generating the IGF signal. The collapsing magnetic field produces a CEMF in the primary coil. When CEMF is detected by the igniter, the igniter sends a signal to the ECM. This method is no longer used.
IGF Detection through Primary Current
I., Primary current lA Maximum current level for successful spark generation ^
lB Minimum current level for successful spark generation T852f135
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