sim wrote:It works!
HOORAY :-) Congratulations!
rewiring the CAS using two lengths of coaxial antenna wire
LOL, fantastic! :-)
With a flat ten degree advance map, the engine started right up
and ran. Revving the engine causes the timing to flutter
slightly, no more than 1 degree back and forth.
But it's rock solid stable while at any given fixed RPM, right? It should be. Any jitter there is CAS drive slop, most likely. The error while revving suddenly is due to a difference between reality and last calculation, but for you, that difference should always be minimal. One day we'll add an option to predict, but I suspect we're better off without it anyway.
I created an initial ignition map
I still think that is too aggressive in the medium pressure ranges. If I were you I'd back timing out of it there and bring it back in as you tune. You're safe at about 32* from 3k up at any pressure level, and you can add more at lower pressures, but I think it's too steep from 100kPa to 60kPa. I could be wrong though, just urring on the side of the conservative! :-)
With the initial ignition map, the engine runs very smoothly.
There is a noticeable difference from the old points set-up.
Is the noticeable difference that it's more smooth or what? Just clarifying. It's good to hear good things about the system, that's all :-)
The car ran very well, except for occasionally losing sync.
Great to hear! :-)
The sync loss happened fairly randomly, but seemed to occur more often at idle, and when well loaded.
Most likely that was just a perception thing. It's
*much* more obvious when under load or at idle.
By the top of Burnaby Mountain (about 300 metres of climbing) it had stumbled enough times to generate a considerable backfire. Somehow, this caused the #1 plug wire to come loose.
You've got a datalog, though, right? If you're going to do significant testing, let me know and I'll send you a good custom datalog generator file to use so they are maximally beneficial.
The next step is to get set up for datalogging and diagnose/fix the sync loss.
OK, that answers my last question! Yep, the logs record where sync was lost and why, so we'll get some good info out of that. Most likely your wiring could still do with some improvement. You could add a very small cap on each of the inputs from the CAS too, but when I say very small, I mean it. The phase shifts from larger caps are not acceptable at higher RPM. We can discuss this when you're next available. Another thing you could do is stiffen the pull up resistors that the CAS pulls down. That will allow a larger cap to be used and in and of itself increase noise immunity. Another thing you could do is add a Schmitt trigger on each input. If the noise is bad enough, though, this won't help.
http://en.wikipedia.org/wiki/Schmitt_trigger
So then:
- Wiring first
- Tiny caps second
- Pull ups third
- Schmitt trigger fourth
We really need you to have a clean signal so we can develop the scheduler and decoder further. Once it's in good shape it will make sense to revert and try some software fixes for noise, but not until after the foundations are really solid.
At the end of the day, though, the software can only do so much,
shit in, shit out, or in our case, shit in, nothing out, briefly. Shit out is bad for rods and pistons and headgaskets :-)
Video is coming soon.
Hooray! I hope your soon is sooner than my soon... I have many FreeEMS videos to upload... one of these days soon... :-)
Fred.