Spark plug fouling detection for ignition system
A method for determining a level of spark plug fouling and providing an indication to change the spark plugs of an ignition system is provided. The method includes providing a dwell command on a control wire of an ignition system and generating an indication of a recommendation to change a spark plug of the ignition system based upon a current on the control wire.
1. A system for determining a level of spark plug fouling and pre-ignition, the system comprising:
an ignition coil for an ignition system, the ignition coil including a primary winding and a secondary winding;
a spark plug connected to a high voltage terminal of the secondary winding;
a first battery connected to a low voltage terminal of the secondary winding;
a feed-forward diode with sensing resistor network connected between the low voltage terminal and the battery;
a comparator receiving input from a reference voltage and a sensed voltage tap connected to the feed-forward diode, where the reference voltage is a voltage set ratio-metrically between a second battery and ground;
a logic OR gate receiving input from the comparator and controlling a switch;
a first current sink connected between a control wire and ground while the switch is closed;
a second current sink connected between the control wire and ground; and
a controller configured to execute non-transitory instructions to:
provide a dwell command on the control wire of an ignition system; and
generate an indication of a recommendation to change a spark plug of the ignition system when a current on the control wire drops below a predetermined value after a threshold period of time has elapsed after the dwell command is provided, the current on the control wire measured via a current sensor.
2. The system of claim 1 , further comprising a first resistor and a second resistor connected across the feed-forward diode.
3. The system of claim 2 , wherein the first resistor and the second resistor are connected in series.
4. The system of claim 3 , wherein the first resistor and the second resistor are connected in parallel.
5. The system of claim 1 , further comprising an input tap coupled to the control wire, where the input tap is positioned between the first resistor and the second resistor.
6. The system of claim 5 , wherein the input tap provides the sensed voltage tap to the comparator.
7. The system of claim 1 , where the first battery is a vehicle battery.