MicroSquirt.com read only forum (Jan.15,2018)

I want to report some success. :yeah!:

I wired Optoin + to Vref and wired Optpin - to the HEI "R" pin. The engine started right up in the base timing.

Initially I was going to use fidle to turn on computer ignition timing, I think I'm just going to route the EST bypass through an oil pressure ...

I really hate throwing in the towel. So I plug in an arduio into my laptop, load it up with a 16 hz 5 volt square wave program. With tunerstudio running and the anode pulse hooked to the distributor connector, I now have RPM and injection.

Now I'm wondering if I shouldn't reverse my Optoin+ and ...

Just an update if anyone is following this thread. Sent my microsquirt back to EFI Source. It looks like they replaced R20 with a 500 ohm resistor. Mike said it would be of a higher wattage. It looks to have 102 or 201 printed on the top. He added a note that said "tested".

Anyway, my results are ...

Today I found a mistake in my wiring. I grounded the sensor ground circuit to the engine. It is also the same spot I grounded the ignition module.

Could that cause an open in R20?

I talked to Mike @ EFI Source and he said every unit, they sell, has been tested. He said "send it back" and he'd ...

Took the cover back off the Microquirt, placed my meter leads across R20 and it shows open.

I'm not sure if that would affect the use of VR1.

The only thing I can guess is that I got someone's returned unit.

Thinking that my chinese Skip White distributor module wasn't sending a clean enough signal, I turned my Arduino into a square wave generator.

5V @ 16.7 HZ hooked to Optoin+ equals no RPM signal in Tuner Studio. I think that circuit's dead. I took the covers off the unit and :shock: :shock:

those ...

I've made my nice neat harness into a rats nest tracing circuits to make sure they are correct. If there was any positive outcome is that I improved some circuits in and out of the pre-assembled bussman relay box I bought.

Things I've tried -
Ignition reference from the HEI module to Optoin ...

Last night I wired Optoin- to ground as suggested in the instructions. I still get a flashing (ground) logic probe signal on Optoin+ but no RPM signal. I did notice that the voltage on my probe dropped to .9v from the 2v it was seeing with the Optoin- floating.

I then wired a LED to the accel LED ...

I'm glad you posted the file extension. I had to look for it.

TIA for any insight you can share with me.
1972 Suburban 1_2014-07-05_18.30.46.msq

I think I'm finding some inconsistencies in the manual. From this page: http://www.useasydocs.com/details/GM_7pinHEI.htm
it says:
tach signal is a ...

New guy here but not to fuel injection or conversions. I did a forum search and didn't see anything I haven't checked :RTFM:

New V3 Microsquirt I bought two years ago installed on a 350ci with PFI (stealth ram) fitted into my '72 Chevrolet Suburban 4x4. I'm using a small cap (8pin) HEI

I finally ...