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

I am having trouble getting a spark. I am running the ignition coil through a BIP373 ( directly to the coil) and the input is coming from a pertronix points replacement. The voltage drop across the pull up resistor is 7 volts and when the points ( pertronix ) are open, and when the points are closed the voltage drop across the pull up resistor is 11.4 volts + the voltage drop across the pertronix is 0.6 volts. This tells me that the the difference the MS detects between open and closed points is 6 volts. What voltage drop does the MS need to detect to trigger a spark? I have the input capture = falling edge, crank trigger - trigger edge, coil charge - standard coil, spark output - going high. Is there a jumper I missed inside the MS?
When I removed the Pertonix switch and connected pin 24( with the pull up resistor) to a set of points on a standalone dist, the coil sparks fine when I give the dist a spin.

Blair

Are you getting a steady RPM signal? If so, the input side should be OK and you'll need to focus on the output side. If you aren't getting a signal, check to see if you can get an RPM signal on the Stim.

I verified the input signal by observation of RPM on the tuner studio, therefore input is O.K. On the out put to the coil ... I removed the coil from the circuit and put a 10K resistor in its place ( between pin 36 and 12V supply) . I connected an oscilloscope across the resistor and measure 12 volts across the resistor in steady state and when I started cranking it had voltage dropped to 8 volts and oscillated between 8 and 7 volts. When the cranking stopped it would go back to 12 volts. My understanding is that this waveform should be between 12 volts (probably 8 volts because of the starter drawing current) and 0 volts to produce a spark. But it only drops to 7 volts. I checked for R57 and it isn't installed. Any ideas?

That's not good. How exactly is the BIP set up?

the BIP is installed into the V 3.57 board as per instructions. I moved jumper from center lead to of where the BIP373 should have been and soldered it into IGBTIN. Then I soldered the BIP373 into the three holes and attached with a Mica strip. I verified it is insulated electrically from the heat sink.

I cleaned up the area where I soldered in the BIP373 with alcohol and a tooth brush. I reassembled the MS and installed it back into the truck. I purchased a new ignition coil for an early model chev 350, one that requires a ballast resistor. The truck started and idles... at about 1500 RPM. I think I have some tuning to do and start doing some data logging to determine why it idles so high.
I appreciate all the help you have given me thus far and look forward to any help you can supply in the future.

Blair

1951 International L120 truck, Silver Diamond 220 CID engine, fitted with 1988 chev 2.8L TBI injectors and sensors.