Megasquirt Support Forum (MSEXTRA)

Hi all... I'm about my witts end here.

I built a MS3X for a 2000 Miata.

I have it set up for VR, with the filters on both the expansion and mainboards set to 2.5v on the corresponding resistor (r54 on the mainboard) and the hysteresis set full ccw. There are jumpers to VRIN and VROUT, as well as a 5v pullup from VCC on the unused R13 (for the opto crank in circuit) onto the resistor below it, R45; I followed this guide https://trubokitty.com/#/ms3xassembly

I have tested continuity on my harness, as well as the entire VR circuit... The only fault I found was a lack of a ground connection via R55 to U7, and I jumped it over with a wire.

I have confirmed that I am getting 5v (I think?) to my crankshaft position sensor from the pull up...

Everything works, fans, TPS, injectors, spark, fuel pump primes, I even get a consistent camshaft signal, but I am not getting a crank signal...

Is there anything else I can do to troubleshoot what the issue is? Maybe with Q23 and Q22? I have only a digital multimeter right now, no oscilloscope... Was considering getting one, and might, if need be?

Thank you!

I took a quick peek at that "kitty" build info (noting that they don't know how to spell "turbo" correctly). It starts out with various mods to the CKP detection circuit, so our ability to help may be a bit limited since your board is non-standard. What help does that other site offer? Frankly, I would take the board back to a standard build, per the manuals linked-to above. A bit of bother? Yes, but when you find you have dug yourself into a hole, the first step is to stop digging...

it's a pretty regularly used guide made by the admin @ miataturbo.net... The only modifications I'm seeing are not using any of the optoin circuit, because it is VR, and then you're pulling the VCC from the unused 13 down as a pull up for the sensor.

https://www.diyautotune.com/wp-content/ ... 3pcb_3.gif

I guess I could try assembling fully, but, I was hoping to troubleshoot the signal or components on the VR circuit by testing voltages to determine if it is actually working, or if not, where the signal is breaking on the way to the MS3 processor.

Can it get an RPM signal on the Stim?

I dont have a stim, been benchtesting in car