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MegaSquirt Next Cylinder Mode
Set up

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.

If your distributor is currently set up for a static timing of about 10 BTDC then the Next Cylinder Mode is the easiest to set up and get running. You can use the Next Cylinder mode to get started, and decide later if you want to move to This Cylinder Mode.

First set up TunerStudio to help you time the distributor. Set the center LED on the MegaSquirt front panel to show the state of the Trigger. These settings will be under Menu Basic Settings > Codebase and outputs Function.

To do this set Distributor to MSnS^,  LED 19(D16) to IRQ trigger. This LED is usually set to Warm Up. Click on Send to ECU. Here is a subset of the settings in the dialog box.


For your safety, you must disconnect power from the coil to prevent a spark.

With the distributor ignition input wired, coil disconnected and ignition on:

  1. Set the crank at 10 BTDC (or your engines static timing) at cylinder #1. This must be less than your minimum advance.
  2. Rotate the distributor in the direction of normal shaft rotation until you find where the center LED is just OFF and the rotor points to #1 cylinder spark plug tower.
  3. Rotate the distributor in the opposite direction just until the center LED turns ON (sets the Trigger Angle & Cranking timing)
  4. Make sure the rotor arm points towards the correct contact (#1 cylinder) in the distributor cap. This is very likely close to the position of your original distributor when correctly timed.
  5. Fix/fasten the distributor
  6. Test the setting by turning the crank to about 20 BTDC the center LED should be OFF
  7. Rotate the crank in the direction of rotation and estimate the angle where the LED just turns ON. This should be about 10 (or your engines static timing).
  8. Enter 10 (or the engine static timing) in Trigger Angle. You will adjust this dynamically with a timing light later.
  9. Enter 10 (or the engines static timing) in Cranking advance Angle
  10. Enter 10 for Fixed angle (This forces the advance to be 10 BTDC)
  11. Set Cranking Timing to Trigger Return
  12. Turn off ignition and connect ignition coil
  13. Start the engine
  14. Adjust the distributor until the timing light is at 10 degrees (or the engines static timing) entered as Trigger Angle above. This should be close to your distributor location above in step 1 & 3.
  15. Set "Fixed angle" to -10
  16. This completes the setup for Next Cylinder distributor ignition 

Example settings for Next Cylinder mode. Trigger Angle less than 20 determines Next Cylinder mode. The Spark Output Inverted selection depends on your install and is not dependent on the choice of This/Next cylinder mode.


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