Autonerdz forums

Yes I'm aware of it.  How many degrees late it is depends on the engine speed the time value is fixed. As long as your not using your transducer to check timing against electrical signals it all relevant though.  Some transducers are faster than others but I think you'll find all are slower than the electrical signal. As long as you are aware of the delay you can compensate for it when checking what the transducer sees against an electrical signal such as your doing there with the crank sensor. If you dig around in the archives on iatn you'll find some vacuum and running compression waves put up by some fella from Russia or maybe it was a link to his site and his transducers were very fast. I remember questioning him about them at the time and the delay was almost nothing as compared to my pv/500.

Like I was telling you, the gas stretttttches; so the electrical is the ONLY way to go to get TDC- the Fluke is no tool to use to determine TDC in the first place. I mean it is not an inaccurate tool so much as it is the wrong tool to use.
   Imagine a tank of gas and the fuel sloshing in it. If you give the gas a shove from one side of the tank, it doesnt register on the other side of the tank till the wave created gets there. Like a wave created by wind a thousand miles away across the ocean takes days to make the crossing and land in Oregon to the south of Tom. If you had a scope and measured the shove where it shoved, it would show you when the shove happened but the Fluke cant record it till it gets to Oregon (and thuslythere  made an impression on the Fluke). These principles and phenomenons are what the OEM is dealing with when he mentions resonance and introduces valves into the intake and high speed runners and idle or mild load runners.
   Gas is more stretchy than liquid. The action of the motor operating actually involves inertia... I mean, the intake is pulling that air in and if you really pulled that piston down hard past BDC and slammed the intake valve shut AFTER BDC; a bit of air kept entering the chamber even though the piston was either stopped or on it's way back up... it was pressurizing even though the piston was attempting to squeeze it back out, by inertia- much more noticeably than liquid which is non-compressible.
Resonance is more like vibration than a simple wave (like on the water example), so I imagine a LOT of what we see with these transducers is due to it.  It would be more hash-like and would appear at differing load conditions, but only under the right ones, like say, idle only or cruise only. I am impressed with how you fellows have been figuring out the FLS. Thanks.

For Mike Webb,

Your getting good with that Anno Wave.  I'll have to try some of those features out this weekend

Lest we forget....The Russians were first in space and first to land on another planet.