I don't know that the OP does, but for anyone who likes to fool around with anything like this I posted this. It's free and it's fun if anyone is trying to do something like this. So I'll post it again because it's cool!

"If you’re an inquisitive fellow with a little time on your hands, do a web search and you will find freeware which can allow you to use the soundcard of a computer as a digital recording oscilloscope, a program such as this and a test lead can be used to detect signals and then generate a time/amplitude pictures of the waveforms. The frequency upper range limit is not that high but if the signals used in theses systems are single RPM events a simple setup like this should be able to do the trick.

Here’s a quick list of stuff like this!

http://www.google.com/search?hl=en&s...AAAKoEBU_QsUX6"

Most of these programs also can be configured as spectrum analyzers in the audio frequency range. I've never yet made use of it but I suspect that something like that may be useful in diagnosing vibrations emitting from a running or moving vehicle. You might be able to visually observe the graphical representation of a vibration at the same time as you hear/feel it in the car. The specific frequency of that event could help differentiate if it coincided with engine RPM or some harmonic of that, or if the frequency was related to some rotational element of the drive train like a drive shaft, diff, axle, or wheel. One of the interesting things I picked up along the way is a sensor for detecting audio frequency waves which is very inexpensive, common and effective, is a piezo-electronic transducer most often used as a buzzer in electronic equipment. Usually there is a thin brass disk with a sliver of piezo material cemented to it. They have one lead attached to the brass and the other attached to the pieso material. This device will detect virtually any touching of it; clamped to a surface it will detect any vibration (I originally used one as a pick-up for an acoustic guitar many years ago and as a sensor for synthesized drum pads). I've used one held against a machine with a clothesline clip to capture vibration wave forms.

I'm all but certain that one could be used very effectively to detect injection pulses in diesel injector fuel lines. With one of these Sound Card PC O-Scopes one could detect and visually compare TDC waveforms and Start of Delivery waveforms simultaneously using the scopes dual trace capability.