MS1-Extra

MegaSquirt v3.0 Ignition Output
driving single coil

Only for use with the MS1 Extra code (MS1 - 68H908 based microprocessors)

By Philip Ringwood (daxtojeiro), James Murrey (jsmcortina) and Ken Calver (muythaibxr)

Please Note:

All of these instructions / diagrams are to be used at your own risk, like most things there is more than one way to do the same thing, what we have tried to do is to offer a method that we have tested or that others have tested for us. No warranty expressed or implied.

Use at your own risk.

MegaSquirt v3.0 can directly drive a single coil. Use this configuration if you are driving the coil directly and not from a coil driver other than MegaSquirt.

Inside MegaSquirt make the green connections::

  1. Remove R57
  2. Solder one end of a 330 Ohm resistor on to the top of R26
  3. Connect other end of 330 Ohm resistor to IGBTIN with a wire
  4. Fasten wire and resistor with RTV to keep from vibrating loose.
  5. R43 may be removed and replaced with a thick wire. If you have a scope, you can use it to measure dynamic coil current and set the dwell.
  6. Connect IGBTOUT to IGN to connect the coil driver Q16 to pin 36.

Connect the '-' coil to pin 36 of the connector.. It is good practice to provide the coil its own ground return and twisting the wire together with the live coil wire (pin 36) but it is not essential. Try to isolate the wire at pin 36 by grouping it with the power ground wires (not the sensor wires) and using wire with thick insulation (use the highest voltage automotive wire available). If there is not already an automotive condenser (metal can with tab for ground) at the +12 going to the coil, add one for improved noise immunity. The +12V to the coil must go either to the fuel pump relay, or if a ballast resistor exists, the original + coil terminal wiring can be used.

In this configuration, you must set Spark Output Inverted entry to Yes

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