PicoScope 7 Automotive
Available for Windows, Mac, and Linux, the next evolution of our diagnostic scope software is now available.
Is PICO 4425 Filtering?
Is PICO 4425 Filtering?
Originally posted in "PICO 6 Software". In the middle of a diag on an older Transit Van with factory LPG (Necam), the LPG system uses a coil signal through a filter for its RPM signal. Fault (engine misfire) is showing up on the LPG diagnostic software as a high spikes on the graph for RPM and jumping to 6 or 7k on the digital display. The question I have is that when I connect the PICO (20v no filters) to the output side of the filter (at the filter or the LPG ECU) the spikes disappear and the misfire disappears, checked for pin fitment issues (none), if I leave the back-probe in the connector and disconnect the scope lead from it, misfire returns. Tried this with a DVOM problem remains, so what is the PICO doing, do I just need to put a 10meg resistor across the circuit.
Last edited by maxgas on Sat Feb 19, 2022 8:26 pm, edited 1 time in total.
Re: Is PICO 4425 Filtering?
Maybe lpg ecu input signal filtering is bad and being high impedance circuit, then every connection matters. If that’s what it takes, play with some resistor or capacitors and let it go.