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Ref /sync error on M1 platform

MoTeC M1 Software Tutorial

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Can someone more experienced explain how can one calculate hysteresis and debounce for engine speed and sync sensor( from input capture) , getting a random bad pitch on fast engine decel after paddle upshift ( as soon as engine enters shift strategy and the rpm changes the sync is lost) diagnostic so far is bad pitch and small pulse detected on sync( both hall sensors) ?

I am assuming you have a very light driveline, so the RPM's drop very rapidly on a shift cut. Can you tell us some about the engine, RPM range when this occurs, Engine Speed Reference modes, trigger pattern, Variable Cam, etc.

The GPx packages from MoTeC have a good helpful drawing in the Help for the Engine Speed Pin Hysteresis (applies to sync as well). Typically a single value of .3-.5v works well, with a threshold midway between the high and low voltage seen with Input Capture.

Again, the help for Engine Speed Pin Debounce is also very good. Unless you are seeing "Threshold Noise" or "Hysteresis Noise", you are probably OK with debounce values of 20 uS for the top 2/3rds of the rev range. Values might change depending on the number or trigger teeth.

Have you tried increasing "Engine Speed Reference Wide Pitch Threshold"? This is the parameter that must be adjusted to deal with rapidly decellerating engines with few trigger teeth. Especially if Engine Speed Reference Diagnostic shows any "Missed Tooth" errors.

As David said, details on the configuration are needed as different reference modes will require tweaking to get them correct. With Hall sensors, the Hysteresis will typically be 0.5V and the Debounce 10ms with a Threshold of 2V. As the Hall Effect signal has already been filtered in the sensor and stays consistent irrespective of engine speed, the M1 doesn't need to do much filtering of the signal when it recieves it. Magnetic sensors need more variance in their settings to deal with the changes in amplitude ofthe signal as the engine speed changes.

Bad Pitch errors occur when the M1 sees an edge outside of the calculated window, this can be caused by a rapid change in engine speed (i.e. shift cut activation) or noise on the signal. If the error is momentary and only occuring during a cut, then i would look at the cut settings and see if they need to be as aggressive as they are to see if the rapid changes in engine speed can be reduced.

What sounds to me to be happening in your situation is that you are getting some valvle train lash, this is leading to the sync edge being either misplaced or read twice as the cams are rapidly oscilating. I would look at the shift strategy first, before I changed settings in the Reference Mode.

Hi ,

Thanks everybody , i increased wide pitch treshold to 180 and it works perfect now( seems that engine was decelerating a bit too fast on cut / it has very light internals, small 180mm carbon clutch and carbon driveshaft) It probably had to agressive cut on shift. I will try to.use more retard and less rpm limit.