Using the Microphone with the Pico NVH

I am not sure what I should be hearing. Is there a rattle type noise along with the knocking?

I am very interested in having a good technique to reasonably pinpoint a noise source prior to disassembly.

Hi Bill, 

There are two distinct noises, one that fades in and out and the other seems to appear. Channels A/B/C are stacked on top of each other which come from the NVH module with the microphone sensor attached. I doubt that we'll be taking this one apart but this is part of why I wanted to have a look. 

Scott - sounds terrible. Might be interesting to see and hear same test with cylinders 3 & 6 deactivated.

Another simple question - 2nd in 24 hours! This question is pertaining to your pattern from channel D with #1 injector events. Specifically referring to the smaller spikes you've marked as the 6 cylinders in their firing order on the same channel; are these the spikes from COP events coupled into the injector waveform via their connections at the PGM relay / power distribution bus bar common with the injector's power feed? If so it looks like a very efficient method of getting a sync from each cylinder. Excuse my ignorance - my goal for 2019 is to increase my scope knowledge so your answer will be one step in that direction!

Thanks

Hi Dave,

I didn't study a wiring diagram for power distribution on this vehicle yet, however, when I saw the spikes I assumed that they were secondary hits which provided me with an additional point of reference.

Very cool scott, ive done similar with GM knock sensors, ill see if can remember to post a pic of my setup. One question, why use the injector signal as a reference mark?

The injector signal wire was the easiest to get to without any disassembly. Fortunately the secondary events were revealed within that trace.