For 5 cylinder and odd-fire V6 engines the crank trigger is not enough. The ECM must know which cylinder (which sparkplug, which transformer, which IGBT) to fire

5 cylinder engine can also run in some sort of 'wasted spark' mode with 5 coils without cam sensor...look at this picture:


Every igbt fires every 360 and they are separated with 72. Can it be done with vems?

GenBoard/VerThree has input for cam-trigger (secondary trigger) and enough outputs to drive an 8 cylinder fully DIS setup.

Beware - think twice if you really want to depend on camsync

For even-fire engines wasted-spark can be a better (and certainly simpler) approach. It is simpler to configure the ECM for wasted-spark, since cam trigger is not needed (so less things to break). Wasted spark wastes very small amount of energy, only about 8..10% for real wasted spark, when the same transformer fires 2 cylinders' sparkplugs, since the voltage will be smaller on the exhaust stroke cylinder while current is essentially the same.

For trendy COP (coil-on-plug) installations, cheating wasted spark really wastes some energy, because the exhaust stroke cylinder's sparkplug is also energized fully.

Countrary to popular beliefs don't need camsync for

Camsync required for

Requirements for fully DIS ignition setup

Note that this applies to coil type primary trigger, and 1 pulse secondary trigger.

In 1.0.x firmware the camsync-active-edge must be between given 2 cyls' spark event! In other words, if the camsync pulse overlapd the used ignition advance range of a cylinder (sometimes spark comes before, sometimes after the camsync-active-edge), it's currently not supported. For a 4 cyl, this means that if ignition advance is set to 8..45 degree BTDC, than the chosen camsync trigger pulse (the edge that is configured to trigger the processor) must be outside of that 37 crankdegree window (out of 180 crankdegrees) plus some safety margin.

This is not a hardware limitation, just a firmware shortcoming, not required in 1.1.x firmware.

The exact reason is the simplified operation in 1.0.x:

Cam-trigger is just used to "reset" engine.igncount=config.ignchmax so the h[2] index jumps to the last element right after the spark-event following the cam-pulse

Even in 1.1.x, you want to make sure that the


Therefore the following config variables are not used (but recommended to set them to reasonable values for future compatibility):


Anyway, for a dual trigger setup make sure you plan cautiosly, and document your progress in wiki so others can warn you should anything be done differently. Test the configured setup on table.

Only cam, no crank trigger - cu

Above we assumed that besides the cam trigger there is always a crank-trigger (the crank is the preferred source for timing as the cambelt usually causes a few degree sloppiness). However a cam itself also enables us to run an engine.

See also: GenBoard/Manual/InputTrigger

Go back: GenBoard/Manual

Can someone please explain how to setup squential ignition with 4 cop's on 4 cyl even fire engine. Please elaborate this commands(and other if needed for setup):