Bike died on the dyno

[SQLGUY]

Sorry, but I'm afraid I don't understand your setup. VE to me means volumetric efficiency. Microsquirt has VR (variable reluctor) + and - inputs on pins 32, 33, and 4, and optoisolator + and - inputs on pins 30 and 31. I would think that a non-zero crossing signal (like the coil drive signal) should go to the opto inputs, but I'm not sure. I'm using VR sensors myself.

For a zener regulator to safely clip a pulse, it should be set up something like this:



The resistor should probably be 1K or so. This is well high enough to not affect the coil drive signal, and well low enough not to make much difference compared to the input impedance of Microsquirt. The output from this ciruit should be a squarish wave with max amplitude determined by the zener voltage. It should not have much of a negative component, since the zener would act a damper for negative spikes, so I would expect to feed this to the opto inputs.

If you're feeding the VR inputs then you would be relying on the negative spike(s) of the switching noise to trigger the zero crossing circuit. How much of a negative spike exists at the switched side of the coil depends mainly on how damping has been set up for your ignition drivers. If there's not much damping, then that negative spike could be pretty big, so you'd want a zener to clip that as well:



Do you have a scope so you can look as this input signal?

[pommie02]

+ve = positive
thats how i was taught to write it....it gets lost in the translation.
i am going to try a different way to connect up a resistor....newtyres suggested it

[SQLGUY]

Im using the option +, - ve with a 24v zener diode.

Now I get it... not option, but optin (opto-isolator input), with the 24v zener hooked up somehow and the - input connected to B+ (12V).

Well, the 5K die still sounds like a tach input overdrive problem, so let us know how the resistors go.

Cheers,
Paul

[pommie02]

Paul
in the first pictue for the opto in
am i cutting the coil negative wire and fitting this circuit in to it or am i creating a new loom that is connected to earth going through the zener and resistor and then splicing in to the coil negative wiring

[SQLGUY]

Add wire as needed, but, effectively, the zener would go between ground (non-marked end) and optin + (marked end); the resistor would go between optin + and the switched (negative) side of the coil. You would not cut anything, except as needed to splice the resistor connection to the coil negative terminal connection; i.e. the coil would still have its original supply voltage and ingnition connection in addition to the connection to the resistor.

Optin - could go to +12 or ground. The difference would be whether you select rising edge or falling edge triggering.

[newtyres1]

To clear this up a bit, the pic might help. What I suggested to Pommie02 is how I ran my bike for quite a while with no issues on a V2.2 PCB Megasquirt. The are some differences between the V2.2 and uS schematics, not sure how significant these are. Originally Pommie02 was running the diagram at the top.

Ian.

[SQLGUY]

That does help. The second layout looks like a good idea. The first could result in some very narrow, or even missed pulses, and would really depend on how much bucking and ringing you got when the coil was shut off.

[newtyres1]

Just for info, it looks like the 2nd cct has faults. It looks like the ringing of the coil (or something?) can cause an extra low spike as seen below, after the event of the coil negative going low, and was seen on every tach event. This scope shot is with the positive lead on the tacho input pin of a MS2. In MS1-Extra fuel only and MS2-Extra 2.0.1 odd-fire dizzy mode, no problems, but in MS2-Extra beta 2.0.2 fuel only, the extra spike caused rpm problems, so it depends on what the code is doing as to what the result will be. I replaced the 0.22 cap with a 1uF cap and this fixed my problem, or should we say masked it. Most if not all people, however, find the top (standard) circuit works fine, and some don't even need the zener diode apparently. I prefer the 2nd cct only because it may help keep coil flyback noise out of the Megasquirt.

[pommie02]

i finally deceided to try and tune the top end revs and throotle on my bike.
i thought the dyno would be the safer option !
the problem is megatune kept resetting...and once the revs started going over 5000 the whole screen kept freezing.
i am using the latest version of megatune, with a serial to usb adapter. i never have any problems connecting....
the only thing i did notice that a couple of the gauges kept flickering.
the dyno guy said he had seen this before...it is caused by sonic vibrations ?
my laptop did crash and i got the windows blue screen.

any thoughts on this ????

[pommie02]

any help with this one...i am ready to burn it.
new pump, new relays, new generator, wiring checked.
i cant ride the bike over half throttle, the engine dies..
i have to operate the kill switch to get it to run again, i did a datalog... it shows a reset, but the voltage stays the same, so it isnt loosing battery power.
it doesnt make sense...