Possible V3.0 board issues

[rickb794]

My latest build is exhibiting bizarre behavior, RPM jumping around, and other signals spazzing out 2nd ignition output absent tach output is flashing, sync indicator is green.
I swapped out the processor after reloading 3.2.4, and it does the same.
I have also loaded different MSQ's with no joy. 4pule checked the input capture settings (not my first rodeo)
A thorough visual inspection shows no irregularities. Polarity on all diodes is good.
I suspect a bad board, the only thing I can find is scoping the Opto output it has a sloped tail from the plateau to zero line (Jim Stim jumpered for square with 5volt pull up) shows square going into opto.
Went to verify my opto circuit mod (used many times on a Neon) and all the old schematics are gone. VR now recommended input circuit.
Attempt to trigger log comes up with flat line.

Any testing or other diagnostic recommendations?

I am thinking of removing the opto out jumper and see what it does with no tach input to the processor.

Does the newer code no longer support the opto hall pickup mods?

[DaveEFI]

If the signal from a Stim is solid, but not from your hall effect sensor, it would seem logical to me that the fault is with the hall sensor or wiring. The actual opto isolator usually works or not.
All the old parts of the manual are still there - just moved. If you were using a direct link, click on the manual link at the top of this page to find them, or use this.

http://www.msextra.com/doc/index-ms2-archive.html

[rickb794]

I guess I was not clear, have not installed in car, will not run on stim.

Output from opto has a sloped tail on return to zero, not square wave. Is this normal? (square in)

Can I trigger the processor direct with the signal from the stim, as a diagnostic?

Thanks for the link.

[rickb794]

I have ohmed out all the connections from the tach in through the Opto to the processor pin (irq1).

trying a spare 4N25....

[rickb794]

Same results.

switched to basic trigger and dist output from stim, and it runs. Rock solid.

Switched back to Neon mode, zilch, no rpm, not ready indicator lit.

Other bizzaro symptoms have not reoccured. These were first start missmatched settings I believe.

Tried 3.1.1, 3.2.4 & 3.3.2 Releases. Same symptoms No RPM Not ready.


I reversed the input capture from the normal setting and it works! WTF? Stupified......

[DaveEFI]

I'm not quite sure what you mean by 'Neon' mode.

The reason for the changes (IIRC) is the VR input is now used for all crank sensors, to simplify new builds. The opto for a cam position sensor, if needed, for sequential. If you look a the new instructions you should get guidance for using a hall effect to the opto, in terms of the hardware connections/mods.

[rickb794]

What spun me out was the trigger capture would not work on the rising edge which is what i have used in the past (on identical systems) and what is recommended.

On a whim I switched it to falling edge, and it works like it should. I don't understand why....

Neon mode = 420/Neon crank trigger capure