[ecoxantia]

Thanks - good idea about checking the numbers agree.

As the the negative issue -I thought I'd read that I need a negative-going pulse. Well, I scoped both leads to my injector, with respect to battery earth. A black one is shown above, goes from 1 to 3.5V (after the 100k resistor). Is this OK for a mpguino?

So, I scoped the other injector wire - it pulses from 0 to greater than 20V even after the resistor, so is not suitable and looks like the 80V injector feed.

Numbers on my pressure display fluctuate wildly- I need to scope this as well and find out why.

My leads are all screened as I expected noise pickup from the injection system. So far I've thought of noise on the signal that needs to be averaged; noise pickup that I need to filter out, arduino hardware issues that I'm unaware of, and maybe software issues. This is taking a lot longer than I expected!!