How does Microsquirt know it's "cranking" or "running?"

[ScramblerXLE]

Hey guys,

Backstory: (copied from my other post) I'm trying to do fuel only on a single, fat tooth setup (I know) using the stock CDI system for ignition. The tooth is only about 28 mm long, so it's not crazy long. This is on a KTM 525 engine, and there are not a lot of attractive options for a trigger wheel, and to be 100% honest, I have an adjustable CDI with several maps and I can switch on the fly and I like that ability and would not want to give it up anyway, so I figured I'd try fuel only.

Since I have to leave the stock fat tooth in tact for that to continue working, I made an adapter that wired VR1 in line with the stock VR sensor, and lo and behold, I have a good tach signal! It starts up and idles and there doesn't appear to be any noise or anything from what I'm seeing. Microsquirt seems to track very nicely and never seems to lose the crank signal.

The problem I was having was that prompted my post the other day in the installation forums was the RPM sometimes reading half, normal, or double speed, seemingly randomly. Changing some of the VR noise filter settings and telling it to Check Sync Always seems to have fixed that and it gets a good tach signal all the time.

The interesting thing I noticed once I got that issue lined out was when I kickstart the thing, it never registers as 'cranking,' and it only registers as 'running' every once in a while once it's running. My question is: how does the ECU know that it's cranking or running? It is sitting there revving around between 2000 and 9000 and doesn't show 'running.' What does it think is happening? haha! Does it need to see vacuum from a MAP sensor as well to see itself as 'running?' Interestingly, it has suddenly shown itself as 'running' before, then a few seconds later, the running bit goes away for no apparent (to me) reason. I have a couple log files in the other thread that will illustrate what I'm talking about but they are from when I was struggling with the half/double RPM readings. I can upload my current tune and some MSLs when I get home from work. Bear in mind that all I've been trying to do up to this point was see if I can get a decent tach signal out of my single tooth, so I'm not sure how much of a mess the rest of the tune file may be in...

Thanks!

-Walt

[ScramblerXLE]

Here is a good example log and my current tune.

Thanks for any help!

[24c]

Hi,

You'll probably find that when you kickstart the bike, the VR voltage is too low for the MicroSquirt to sense it, and there's a possibility your add in circuit is reducing it.

If it was me, I'd duplicate the set up on a bench and then play, as it's the only way to methodically sort the problem out. Once you have a good signal in all operating conditions, then life becomes a lot easier, and you can make better progress with everything else.

Numerous folks have played with "long tooth" set ups, and mattgsxr was one of the early ones, and dontz125 has a variation on this if I am not mistaken.

Mike

[ScramblerXLE]

And that makes sense as to why it doesn't ever see itself as "cranking" but if you look at my MSL file, you'll see what looks like a good crank signal to me and it still doesn't see itself as "running." Do you know if Cranking and Running require any other inputs? Could the fact that it doesn't see any vacuum from the MAP sensor be the issue?

Thanks for the reply!

[24c]

Hi again,

The MAP sensor is not used in cranking detection!

Your problem will be the VR sensor on the KTM and the "long tooth", which is much wider than the sensor affecting the zero crossing point.
Go back to basics, or use something else as a trigger. I ripped out the wiring loom on a CDI CCM R30 (Suzuki 644) the other day for my brother, and that had a tacho output from the CDI, maybe you there is something you can use out of your CDI box, besides a detuned HT pulse.

Not familiar with KTMs, but have dabbled with Husaberg engines.

Mike

PS Old link http://www.megamanual.com/ms2/pickups.htm

[ScramblerXLE]

I understand what you're saying from a theoretical standpoint and have done a lot of reading on the topic, but if you look at the MSL file, I don't really see a problem. It happens too fast in terms of ms to matter I think, as the KTM idles around 2000 RPM. If the fat tooth was causing issues we should see sync problems etc, and as you can see in the MSL file, it knows how quickly it's spinning clear as day, it just doesn't see itself as running, even if it's sitting at 4000+ RPM for several seconds without trigger error or anything, it still says "Not Running" why is that? I don't see how that can be the fault of the long tooth as we're not getting trigger errors and the the uS see's RPM. For some reason, it just doesn't seem to equate RPM with "running" or "cranking" which is what I'm not understanding.

[24c]

Hi Walt,
Yep, your bike spins at a high RPM, but without understanding the code, AFAIR cranking is set by the limit in your MSQ, once you exceed this and the MicroSquirt is seeing regular tach, that's synched, you get a running status. As you've set the cranking RPM to 1200, it should be in a run state. Have you tried without the noise settings been enabled. AFAIK, the later software does read half speed sometime, but didn't on earlier revisions, I'm sure I posted about it and somebody else did too.

I don't think there was an official response.

Mike

PS I don't play with this stuff at the moment, and I use something else for the single cylinder and twin engines with VR sensors, but all the testing was done on a bench rig. I would make up a tooth copy, and attach it to a cordless drill, and use the same sensor, and do some proper testing, but I started like you, and then I got nowhere for two years! ;)

[R100RT]

+1 towards Mike's advice. A bench set up (in my case a drill press with variable speeds via the different shives) affords the luxury of total test and proof from zero tone wheel rpms to overspeed if needed to prove everything, whilst sitting in a comfy shop chair and coffee in hand
Its amazing how fast things progress once rock solid sync is achieved.

[hybrid]

Does your CDI have a tacho output that you can use to trigger the Micro?
That's what I used to do on my bike when running fuel only.