This makes Q1 itself suspect, although I'm at a loss to explain the latchup.

The behavior you're describing almost makes me wonder if U7 itself isn't internally shorted in some weird way.

If this circuit were in my lab, I'd be lifting R17 and measuring the current through it to see if it varies when this condition occurs. Eg: is the voltage at ZC falling because it's going to ground through R17 into pin 3 of U7? (Of course, I also have a nice milliammeter in the lab, which is what you'd need to detect a short downstream of 5v through 101k.)

 

Sadly, the circuit is in my garage, which is not well equipt. It is unheated, and getting dark now. Another day shot to ****. Been frustrating.

The circuit is recognized as good at some rpms. I have it running on a JimStim right now. 978 rpm - seems good. 1468 rpm = bad. I have had it running with sync at 5555 rpm.

USB scope trace (at outputs of both circuits) looks ok.

However, TS or MS3 doesn't like it though.

 

Stupid question (from a guy with little experience on the MS3): Can you manually select which edge of the input signals to trigger on? I wonder if one edge of one signal is very close to one edge of the other signal, and you happen to be configured such that you're triggering on those extremely close edges.

Actually, I just went back and re-read the first post. That's kind of an interesting crank / cam combination you've got. Just as an FYI, you don't need a pullup with a true VR sensor.

 

You can select which edge to trigger on for both the crank and cam sensor. Of course, that means it is now possible to screw up 4 ways

There isn't a pullup on my VR circuit. I sure got that beaten into me!

 

JimStim idle led on, fp off. 2976 rpm. First log is composite - shows sync loss.
Second log is tooth logger. Little spurs along with normal ones.

Third log is Tooth log at 6290, seems ok? FP back on, all spark and inj lit (ABCD). Tacho is lit.
Weirdly, Idle led is on.

 

JimStim doesn't always work reliably at high RPM in 60-2 wheel mode. It's too much for the little processor. Try using a less intensive mode such as 12-1 or 36-1 instead.

Generally I do any stim testing using 36-1 mode, no matter the application. You should be able to get 8k+ rpm without sync loss in 36-1.

 

The JimStim signal for the 60-2 wheel mode should be fine to well over 12000 RPM. That limit was lower with earlier firmware versions but it's no longer the case with the V2.0.3 firmware.

One of the problems with the 60-2 signal is that some MS input circuits are filtered too aggressively to let such a signal go through cleanly.

In any case, that doesn't seem to be the case here since he's getting clean composite logs. I have no idea why the apparently clean signal would create a loss of sync. Using another wheel mode could be a good idea but what I would do first is to reload the firmware and use the default settings to see what happens. Then if it works fine, change the wheel mode to 60-2. Finally, try to change the other settings one by one.

Jean

 

FWIW, I get similar, although not as severe behavior on the 36-1 wheel on my JimStim. Some rpms are ok, others are not. It does work over a wider range than using the 60-2.

Guess I have to figure this out on vehicle.

But on the scope, (JimStim) the outputs all look like the trace below.

 

Did you read what I said about reloading the firmware and starting from the default? Do that first on the JimStim to see what you get. If you have problems with the defaults then the issue is your hardware. Otherwise it's a setting somewhere.

Jean

 

I hadn't. You posted while I was still writing. Are you are telling me to reload the ms3 firmware? 1.02 is what I am running. Or some other firmware?

What msq file do I run then?

Sorry, I'm a real noob.

And I just put the ms3 back in the car.

 

You load the firmware and use the msq that comes with it. You don't need to load the msq because it's already there when you load the firmware. And you can use the same version.

Jean

 

Well, reflashing the ms3 and reloading the base tune gives flawless rpm performance up to the fuel cut at 6000 rpm. When I raise the fuel cut to 7200, it works all the way up to there.

Of course it isn't sequential, nor ms3x, nor 60-2 like I need.

So what do I do next?

 

So I edited the basetune in the ignition wheel area to see if I can get the 60-2 to work. This seems to keep sync beyond fuel cut. At higher rpms, like 7900 it is still in sync. (I have sync at 12.5k) It appeared I needed to touch the cam pot r11 to get it to trigger this fast. (Confirmed on a scope)

I'll have to compare the "working" ignition to the non-working.

 

So it works fine on the JimStim ... But not on the vehicle!
Tweaked R11 to get CAM. Works from 700-7000 RPM with the stim. Set the stim cam signal polarity to match the vehicle's. (Normal low, high for pulse)

When I crank the battery voltage on the gauge is 10.5V. When I hear a click in the dash, I lose sync. Otherwise I have sync. Low or bad battery? 12.2V at rest with the O2 powered.

I get occasional bangs when something ignites. There is fuel and spark.
Not sure how to time it if I can't get anything to run. The 60-2 timing wheel is installed with the center of the gap at TDC. The wheel assy is keyed so even I can't get it wrong.

What can I try or measure next? I am stuck. Crank with a jump? CAS sensor wiring issue?

Anybody in the MA or NH area that can help this weekend?