Electric Noise PIC problem

[Dave]

Tobias , Once again, Where are the pullups for the inputs? And what is the purpose of R22 and R25? The schematic looks the same as before...

Dave Purola,
N8NTA

[Tobias]

Dave
I am using the weak pull-ups on the first board/second posted schematic. Maybe you didn't see the second schematic

[mr.sneezy]

Are you actually sensing RPM from the spark source in your project (not sure if your posted project schematic is all of it or just some of it) ?
If so I might be able to help suggest some things. If not, then I'd suggest you try initially powering the project from an independent battery source (dry cells etc) and see if your problems go away. If so it gives a clear indication of whether the source of EMI (if that's the issue) is coming in via the cars own power supply.
Also be aware that any long sensor pickup lines in the car are potential receiving antennas for EMI, and use inline RF chokes before they get too close to the MCU.

[Tobias]

Yes I am sensing RPM on this board. I do have all inputs and outputs optically isolated from the board and I am using a DC/DC converter. The last few days of thinking about this problem, I am wondering if the switch supplying the signal to the WOT is 'bouncing' It is pretty much a generic micro-switch under the throttle pedal. The main reason I am wondering, is that the On/Off input is the same voltage but through a toggle switch. I sent out a board yesterday to test with a 22uf cap on the WOT trace. Hopefully that will fix the problem.