Rolling cut isnt cutting it

[runesmdk]

Pun intended.

Rolling cut of just 1 event per cycle is too little.

On a 4 cylinder, it should happen over a total of 5 ignition events, 4 should cut, 1 fire, reset and repeat.

On a 6cyl, 7 events with 6 cut and 1 fire, and so forth.

That, or atleast half, like 4 cyl, 3events with 2 cut 1 fire.

That way it will keep going through the cylinders and not flood some when in the cut area.

Rolling now barely works even with very heavy retardation

[brunob45]

On my project, I've implemented a gradual rolling cut for launch control, flat shift and regular limiter.

I found this algorithm on Motec's forum https://www.motec.com.au/forum/viewtopic.php?f=11&t=175&hilit=randomiser

This video makes a great job at explaining how a professional rpm limiter works (especially the diagram at the 20 minute mark) https://youtu.be/Au-7kYO4sak

Maybe this is something worth looking into for speeduino also.

Here's a quick example:

#define LIMITER_FULL_CUT_LEVEL (0xFF)

struct Limiter
{
    uint8_t seed;    // randomizer seed, normally 75 or 151 is used
    uint8_t counter; // to keep track of the rolling cut
    uint8_t level;   // cut level, 0=no cut, 255=full cut
};

bool limiter_should_cut(Limiter* lim)
{
    if (lim == NULL) return false;

    lim->counter += lim->seed;                  // update counter
    return (lim->counter < lim->level) ||       // cut if counter is less than level
        (lim->level == LIMITER_FULL_CUT_LEVEL); // or if full cut is enabled
}

Limiter rollingCutFuel;  // to keep track of the fuel rolling cut
Limiter rollingCutSpark; // to keep track of the spark rolling cut

Then limiter_should_cut() is called in every schedule start callback to decide if we actually enable the output pin or not.