Little help getting RPM with Megastim 2.2 on fresh V3 board

[Vortec350s10]

I've just finished building my second megasquirt and am having some trouble getting an rpm signal. I have a MS3 3.0 without the expansion board. If I remember correctly the megastim only works when using basic trigger, which I have tried. There was some confusion in the configuration of the board when building it as far as what components are needed. In the new MS3 base hardware manual pdf, it isn't clear if some of the components it says to set aside are ever needed (top of page 187). I ended up adding Q16 and assembling the direct coil driver as in step 5.3.1.1. I have done the requirements below:

Jumper IGBTOUT-IGN.
- Connect a 330R 1/4W resistor between IGBTin and the top of R26.
- Ensure R57 is absent.
- Ensure R43 is fitted or jumpered.
Typical settings
Spark Output = Going High

I am going to be using a crank wheel on this application and the sensor I have is a Hall effect but it has a built in pullup (bought from DIY website). I am going to be driving a single coil and have jumpered IGN to JS10 on the back of the board. Instructions state to build the VR circuit (5.2.4) which I have done. I have it jumpered like this:
a) Solder a link between VRIN and TACHSELECT
b) Solder a wire between VrOUT and TSEL
Is this setup compatible with the megastim? On my other megasquirt (MS2 3.0) with it setup for the VR circuit the rpm on the stim works fine.

Maybe I started going down a wrong path here but I couldn't help but notice the instructions for the MS2 3.0 board were much more detailed, and somewhere it mentions installing R12. Installing R12 is never mentioned in the MS3 assembly, except where it is included in the list of items to "put aside". I tried installing R12 as well. Is it necessary on a MS3? Is it possible that installing some components in the MS3 instructions were missed? I'm guessing not but I have to ask. It just seemed the MS3 instructions (to actually build the board) are very abbreviated compared to the MS2 assembly guide that I used when I built my first one.

I'm under the impression that since a MS2 and MS3 uses the same board, most of the components will be the same and function the same, with the daughtercard being the only real difference. Does that effect more of the board than I think? I haven't compared the schematics between the two to fully understand the differences.

Sorry this got kind of long, but I know a lot of you guys on this forum are very smart about these, so hopefully you can find the time to help me out a little.

Thanks in advance!

[DaveEFI]

To replicate the signal from a toothed wheel (36-1, etc) you need a JimStim. However, as you've said, to simply check the VR input works you can set the software to work with a Stim. I've found R56 usually needs to be set about 6 turns in to work with a Stim - but it may well need a different setting with the real sensor.

It's much easier with a 'scope. Connect to to TachSelect will show the input to the VR sensor, from the Stim. Connect to Tsel shows the output from the VR section to the processor. What you need to set R56 for is an approx 5v square wave at Tsel - it will probably not read anything or a much lower voltage on the default setting. With a Stim, both the input and output signals should be approx the same.

[Vortec350s10]

Thanks, I will see what I can come up with. I went through the instructions again and noticed something. It sounds like on MS3 you don't use JS10 as an ignition output, but instead you set up the ignition settings for "LED spark". I'm assuming no other internal jumper wires are needed since nothing else is mentioned. Is this correct? Well I've tried it again (I realized I was missing the 330 ohm resistor connecting from top of R26 to IGNTIN). With it set to LED spark, I still didn't get any rpm input. I started following the pulsed rpm signal through the stim and throught the MS3 board until I got to U7, and realized it wasn't soldered! Stupid mistake no doubt. Soldered it in and now it works.

[Vortec350s10]

One more question, can I use JS10 instead of LED spark? I have already planned on my D14-D16 to be outputs to drive relays. Can I jumper IGN to JS10 and use that instead? Any advantage or disadvantage to doing that?

[Matt Cramer]

For basic trigger, using JS10 as a spark output is not a problem.

[racerron]

i loaded the firmware to my ms3x it took me and my girl friend a hour to figure it out . i hooked it up to the mega stim every thing works except the two injector leds on stim. is this because the injectors are now on the top db37 plug or should they still blink. i did not turn the two pots on the main 3.0 board