My engine isn't at its best;
it is from a racing sidecar and has seen some rather extreme modifications!
All the counterweights have been removed from the crank!
The compression is around 16atm.
It is also a bit tired, and has been bored to 1146cc (about 7% over)
Finally, as it is tired not all cylinders share the same compression (these vary with temperature and things, but one is down as low as 10atm at the moment).
These things all add up to variable crank speed whilst cranking. It turns out that this us upsetting my EFI computer into worrying about losing the trigger on the missing tooth wheel.
There are loads of solutions to this (the best being to rebuild the engine so it works properly), but I decided to try to make the triggering more robust, and specifically, to use the stock suzuki trigger wheel (because that approach feels most "right").
Here is some progress (image at top of 'scope screen).
the bottom trace shows the signals from the VR (variable reluctance) sensor.
The top trace is the output from the electronic pre-filter that I have built. I am pretty pleased with this, as the MS2 can detect edges in this signal that are both positive and negative, and hence I am in a good position for the software to deal with this. Note also that the long tooth is about 10x the length of the short tooth, so it is pretty definitive.
Here is the output when I log the teeth using the MegaTuneStudio software.
Now I just need to build a wheel decoder. My first version didn't work, but I found a small (but critical) bug in this, so I am optimistic that I might be able to get the engine to fire tonight.
