MS + Stim = no RPM = wtf?
 

Ok, so I'm finally getting to building the MS, it is hooked up to a stim that Shuiend loaned to me. He told me via PM

"Some of the LED's on it might not light up and I think that might be how I built it. But it does work for everything except rpm and that is because of the mods that are done to make it work with the miata dont work with rpm on the stim"

The MS is done, built per megamanual, and everything seemed to be good. On a different stim (friend started building it a while back, he had it setup for VR sensor) it read RPM output.

On this stim, after we installed the Hall sensor and changed the jumpers to work with it instead of VR and on this stim it does NOT show up RPM.

I'm unsure if that is normal from the amount of post by you guys saying you can't get it, but I don't see post on how you guys finally did or if it is just the stim that I have isn't setup to read RPM at ALL.

Any thoughts?

the stim Brian gave to me with the MS showed stim....Lars might not have built it correctly, but even if RPM doesnt show and everything else works, you can atleast just get your easytherm done msq file loaded and be done with it.

mine showed RPM until I did the miata mods to the MS board, now it doesn't show it.

Hmmm, I just told him to go ahead and finish modding it.

What happens if I don't get the RPM signal working correctly?

then it may or may not work on the miata if it doesnt he gets to rework through it untill the begining

Well, Lars said that he never had RPM working on that stim, but he built it fully before trying to test it.

Hopefully it is just the stim and all is working well.

If it's running MSnSe, did you disable the "Stim for Wheel" option in MT?

RPM didn't work for me once i did the miata mods.

The Miata mods don't work too well with the V2.1 and V2.2 Stims, which are recognizable by having a row of 5 LEDs instead of four LEDs arranged in a rectangle like the older designs. However, it's sometimes possible to make it work if you replace the Stim's R4 resistor with a 180 to 200 ohm, 1 watt resistor. The resistor gets hot but it works for us.

RPM did NOT work BEFORE the Mods. MSNS-E was NOT loaded onto the board. I think it is the old style...only one LED works though.

What the Stim doesn't like is the 12v pullup on the ignition input (which is a part of the 'miata mods'). The stimulator mod Matt mentioned is a workaround for this that typically works...

Also, as someone else mentioned, once you've configured the ECU for use with the wheel decoder (as use on the Miata), which would happen by default if you've loaded somebody else's Miata map, then you must enable 'stim for wheel' in MegaTune to get it to simulate a wheel for the ECU to decode in order to get a steady Tach signal.

Those are the two possible issues, assuming the stim and ECU are properly assembled of course...