How to Use MegasQuirt With the PerTronix Ignitor

If you haven’t already, please read the ‘disclaimer’ at the top of the parent page here.
Updated 1/16/2014

Taking control of the timing

The PerTronix Ignitor is a small, self contained ignition module that replaces breaker points. PerTronix also offers ready to run distributors that come equipped with the Ignitor. If you are using the distributor advance mechanism to control the timing, you can simply follow the directions for fuel only and triggering off the negative terminal of the coil. This article covers the other possibility: locking out the distributor and having the MegaSquirt control timing. When you do this, the PerTronix functions as a sensor for the MegaSquirt, with the MegaSquirt firing the coil. Although the Ignitor uses a Hall effect sensor, it is not possible to wire MegaSquirt to this sensor directly. You’ll need to use the ignition control output instead.

First, you will need to lock out the distributor. With PerTronix’s own distributor line, they have a simple lock-out kit; use part number D703700 for counter-clockwise rotating distributors and part number D9010 for clockwise rotating distributors. For OEM points distributors, how to lock it out will depend on the distributor and may require welding parts together.

Once the distributor is locked out, you will want to adjust the distributor so the Ignitor would fire the coil somewhere between 1 and 19 degrees BTDC, and have the distributor rotor aligned so the center of its tip points at the #1 distributor cap tower at around 20 to 30 degrees BTDC. This is called distributor phasing, and is important to be sure the spark can travel to the spark plugs when the coil fires.

Note that MegaSquirt will not work with the Ignitor III, either in fuel only or using it as a trigger for MegaSquirt controlled ignition. The problem is that the Ignitor III sends multiple spark signals per ignition event, and does not have a tach output with a single pulse per ignition event. This prevents it from providing a usable signal to trigger the MegaSquirt or other electronics. As PerTronix’s Ignitor III documentation notes, “We recommend the Ignitor or Ignitor II as a trigger source for a capacitive discharge box“, (bolt printing in the original) and the same warning applies to using the Ignitor III as a trigger for MegaSquirt or other EFI controllers.

Using the MegaSquirt-I (MS1/Extra)

This is a straightforward option with a V3.0 or V3.57 board.

MegaSquirt-I PCBv3.0 Mods Required:

  • Build the VR conditioner circuit, as described in MSExtra’s MS1 Manual. All our preassembled Megasquirts with the V3.0 board come with this circuit installed.
  • Jumper TachSelect to VRIN.
  • Jumper TSEL to VROUTINV.
  • You may need to adjust the VR trim pots, R52 and R56, when this is installed on a running engine.  A usual base setting is to turn them all the way counterclockwise, then give both a half turn clockwise.
  • Jumper IGBTOUT to IGN to send to IGBT ignition coil driver signal out of pin 36 on the DB37.
  • Cut out R57 if fitted (This won’t be there on my units, though.).
  • Get a 330 ohm 1/4w resistor and cut the leads down to about 1/2″ at each end. Maybe a bit less.
  • Tin each end of the resistor with a bit of solder.
  • Cut a 5″ piece of hookup wire (22ga is fine) and strip just a 1/8″ or so. Tin the stripped wire with solder.
  • Melt the tinned wire tip to one end of the tinned 330 ohm resistor tip and let it cool.
  • Heatshrink wrap this wire/resistor assembly.
  • Use this wire/resistor combo to jumper the ‘top’ (top as in when you facing the silkscreen side of the PCB, with the text so that you can read it normally) lead of R26 to IGBTIN on the opposite side of the PCB.

That’s it!

MegaSquirt-I PCBv3.57 Mods Required:

  • Set it up for inverted VR input: Put the J1 jumper in the 1-2 position, and the JP1 jumper in the 5-6 position.
  • You may need to adjust the VR trim pots, R52 and R56, when this is installed on a running engine.  A usual base setting is to turn them all the way counterclockwise, then give both a half turn clockwise.
  • Install a BIP373 coil driver in the Q16 slot.
  • Get a 330 ohm 1/4w resistor and cut the leads down to about 1/2″ at each end. Maybe a bit less.
  • Tin each end of the resistor with a bit of solder.
  • Cut a 5″ piece of hookup wire (22ga is fine) and strip just a 1/8″ or so. Tin the stripped wire with solder.
  • Melt the tinned wire tip to one end of the tinned 330 ohm resistor tip and let it cool.
  • Heatshrink wrap this wire/resistor assembly.
  • Use this wire/resistor combo to jumper pin 7 of the U1 socket (note: This socket is “upside down”, so pin 1 is in the lower right hand corner) to IGBTIN on the opposite side of the PCB.

That’s it!

External Ignition Wiring

  • Connect the black wire on the Ignitor to pin 24 (Tach on the relay board).
  • Connect the red wire on the Ignitor to a switched 12 volt source.
  • Use a 1K resistor to connect the red and black wires of the Ignitor together.
  • Connect the negative terminal of the coil to pin 36 on the Megasquirt (S5 on the relay board).

MS1/Extra Ignition Configuration

    • Configured for MSnS Spark Output using LED 17.
    • In MegaTune, you MUST set Spark Output Inverted to Yes.
    • Set the dwell depending on the coil; 2.5 to 3.5 msec is usually a good starting value.
    • The Trigger Angle setting will depend on the physical location of the trigger pickup. Often, an angle of 10 degrees will work. To set the timing with MSnS-E, go to the Spark Settings menu and set Fixed Angle to 10 degrees. You can then set the ignition timing to 10 degrees with the engine running, using a timing light. Once you have set the base timing, set Fixed Angle to -10. This will tell MSnS-E to use the timing map.

Using the MegaSquirt-II PCBv3 or V3.57

Note: MS3 can handle this in a similar way. Note that this approach does not allow you to use sequential injection; this would require adding a crank trigger and removing all but one magnet from the PerTronix trigger.

If you’re assembling your MegaSquirt-II from a kit (Part# MS230-K):

      • For the most part, stick with the standard assembly documentation in the MSExtra MS2 Manual.  I’ll just be covering any departures from that doc here.
      • Additional:  You’ll be installing the VR input circuit  (currently all steps under 51). You do not need the components in step 50, although it’s handy to install them in case you ever use the Megasquirt on a different car (or decide to convert your Mopar to a ignition system that uses this circuit).
      • Additional 2:  Set the jumpers for VR input.  That would be TachSelect to VRIN, and TSEL to VROUT.
      • Additional 3:  You will use IGBT High Current Ignition Driver Circuit.  That means you complete step 65.  Install everything just as this step directs you to (which does mean no R57) and install the jumpers to enable the circuit. (IGBTIN to JS10 and IGBTOUT to IGN).
      • That’s it!

 

If you’re modifying a DIYAutoTune.com MS230-C MegaSquirt-II Assembled ECU:

Input Mod:

      • You will be using the VR input circuit. Connect the TachSelect jumper to VRIN, and TSEL to VROUT.

Output Mod:

      • There will be a jumper wire from JS10 over to IGN.  Desolder and remove this (don’t just cut it, you’ll need the holes clear of solder).
      • Install new jumper wires to enable the IGBT High Current Ignition Driver Circuit (IGBTIN to JS10 and IGBTOUT to IGN)

That’s it– you’ve got your Megasquirt-II Engine Management System fully prepared to wire up to the Mopar distributor pickup, and drive the stock coil directly using the BIP373.

If you’re modifying a DIYAutoTune.com MS2357-C MegaSquirt-II Assembled ECU:

Input Mod:

      • You will be using the VR input circuit. Place the JP1 jumper in the 1-2 position, and J1 in the 3-4 position.

Output Mod:

      • There will be a jumper wire from JS10 over to the center hole of Q16.  Desolder and remove this from the center hole of Q16 (don’t just cut it, you’ll need the holes clear of solder).
      • Install a BIP373 coil driver transistor in the Q16 slot.
      • Install new jumper wires to enable the IGBT High Current Ignition Driver Circuit (IGBTIN to JS10)

That’s it– you’ve got your Megasquirt-II Engine Management System fully prepared to wire up to the Mopar distributor pickup, and drive the stock coil directly using the BIP373.

External Ignition Wiring

      • Connect the black wire on the Ignitor to pin 24 (Tach on the relay board).
      • Connect the red wire on the Ignitor to a switched 12 volt source.
      • Use a 1K resistor to connect the red and black wires of the Ignitor together.
      • Connect the negative terminal of the coil to pin 36 on the Megasquirt (S5 on the relay board).

 

TunerStudio Ignition Configuration for Bowling & Grippo firmware:

      • Trigger offset = 10 (this will vary, depending on the distributor orientation, see notes at the end of the article)
      • Ignition Input Capture to ‘Rising Edge’
      • Cranking Trigger to ‘Trigger Rise’
      • Coil Charging Scheme to ‘Standard Coil Charging’
      • Spark Output to ‘Going High (Inverted)’

TunerStudio Ignition Configuration for MS2/Extra or MS3:

      • Spark mode to ‘Basic Trigger’
      • Trigger angle / offset = 10 (this will vary, depending on the distributor orientation, see notes at the end of the article)
      • Ignition Input Capture to ‘Rising Edge’
      • Spark Output to ‘Going High’
      • Number of coils to ‘Single coil’
      • Spark A output pin to ‘JS10’ if using our build guide above
      • Dwell type to ‘Standard Dwell’

Dwell will need to be set depending on the coil. 2.5 to 3.5 msec is usually a good starting point.

More information on setting Trigger Offset:

You must also set the initial position of the trigger (called the ‘trigger offset’), then check it using the Trigger Wizard in TunerStudio  (Tools Menu).  The trigger offset setting will vary according to your distributor position (where it is in rotation) but you’ll need to set it properly…  Basically you use the Trigger Wizard and adjust the ‘trigger offset’ and/or twist your distributor until the advance number in the Trigger Wizard matches what you’re reading with your timing light.  The +/- buttons on the trigger wizard will adjust your trigger offset.  You’ll need to use these buttons and a timing light to make the number on your light, and the big number on the left in the Trigger Wizard, match up.

Here’s the information on this:

Before tuning your advance table, be sure to use a timing light to verify that your ‘trigger offset‘ is calibrated. Changing the Trigger Offset in MegaTune will not change the displayed advance, instead, it changes the actual advance as seen with a timing light. Your goal is to make these two match.

To do this, get your engine warmed-up (otherwise the timing moves as the temperature increases) and idling, then use a timing light to verify to be certain your actual advance as shown by a timing light equals your the advance display on the advance gauge in MegaTune. (8 in this case). (Note that positive numbers denote BTDC, and negative numbers denote after TDC.)