First off this MS isnt going on a miata but this forum has pretty good MS info. I'm trying to put a MS2 on my volvo and I cant get the injectors to fire. The volvo uses low impedance injectors with resistor packs so the circuit is the same as the miata. Im running the ms2 extra 3.03x firmware. It seems to be a problem with the board itself. I threw the daughtercard into my miata's ms and was able to get the miata to start and run.

On the Volvo I am using the output test mode so this should eliminate any problems with the msq. Using an oscilloscope I find that the signal input side of U4 stays high all the time. I tried removing U4 and the pullup resistors going to it so I could look at the signal directly coming from the daughter card but it still remains high.

I then looked for a short between 5V and the signal pin on the daughter card but I couldn't find one. Any Ideas of what else to check?

 

Figured it out. There was a solder bridge on Q14. Also turns out you need the pullup to measure the signal from the cpu.