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Setting Trigger Offset

DISABLE FUEL WHEN ADJUSTING TRIGGER OFFSET

FIRE DANGER

The following guide will provide a general overview of finding and setting the trigger offset value to use in TunerStudio. This is an engine-specific value, but you may be able to use another's settings as a starting point if they have a similar trigger setup on their engine. You should always make sure your trigger setting is accurate to your engine, as this value influences every other value in your tune.

This guide assumes that you have already configured your trigger.

Why Do I Care About Trigger Offset?

In order for your engine to run properly, the ECU must know exactly where the engine is in its rotation. This is determined by your trigger solution, but there's a catch. In many cases, the trigger pattern does not properly align with the position of the engine, and this is what trigger offset is for. Trigger offset is a fixed value that tells the ECU how much the position of the trigger differs from top dead center on cylinder #1.

How do I Set My Trigger Offset?

To set your trigger offset setting, you must determine how far your ECU is from your engine position. The easiest way to do this is to use a timing light on cylinder #1 and check its position on your engine's timing marks.

  1. Have a fire extinguisher ready.
  2. In TunerStudio, open "Injection" -> "Injection Settings". Set "Enabled" to "false", and save the setting. In your fuse box, find and remove the fuse(s) that power your injectors. Drain the carburetors if applicable.

  3. Open "Ignition" -> "Ignition Settings" and set "Timing Mode" to "fixed". Set "Fixed Timing(deg)" to a value that corresponds to a mark on your crank pulley. Zero will correspond to the TDC mark, or your manufacturer may specify different values.

    Fixed Timing

  4. Remove the spark plugs. This will eliminate compression in the cylinders, allowing the engine to turn freely and give better results when checking timing.

  5. Connect a timing light and spark plug to the #1 spark plug wire. In engines with individual coils, you may need to get creative here, such as extending the coil with a spare plug wire to give you a place to attach the timing light. Ground the threads on this spark plug somewhere on the engine.

  6. Crank the engine, watching the position of your engine's timing marks.

    Timing Mark

  7. Adjust "Setup" -> "Trigger" -> "Trigger Angle Advance" up or down (negative values are allowed) until you get spark at TDC. This is now your trigger offset.

  8. Reinstall your spark plugs, re-enable fuel, set your timing to something sensible, (manufacturer recommendations) and try to start your engine. Verify the timing again with a timing light once the engine runs, and adjust the offset if needed.
  9. Change your timing mode back to "dynamic" or you will continue to run on fixed timing and give up a ton of power and fuel economy and have some really high exhaust temperatures.