If re-done the power and grounds, separated the power and signal line runs, then fixed the real main issue which was a dangling ground wire in the center console occasionally shorting out.
Now we get an occasional sync loss between 4K-6K RPM, and I'm wondering if there's any advice.
UAC4 board, with a DSC.
VW ABA engine, full sequential setup with wasted spark (NEW VW unit) the stock VR sensor and shielded wiring. 60-2 crank wheel with a single pulse on the distributor hall sensor, also the stock wiring. The distributor is only feeding the ECU the single pulse signal, there's no spark through it.
The DSC Extra 0.1uf filter cap across the second input to filter the input signal more.
Both outputs on the DSC look extremely clean on my oscilloscope, no glitches or noise. However the output signal level is only 3.3V.
One thing I've noticed is the distributor signal on the composite logger is often weird. Some frames it's missing, some it's fine, and sometimes it's a very narrow pulse. Is this typical? The main signal looks great and the tooth logger is very clean.
The only thing I can think of is there is so much vibration that the DSC or arduino is losing contact somehow because the RPM and load isn't consistent.
Anyone have any ideas?