First-Look pulse sensor

[2ndGearRubber]

I've seen some waveform captures from this, and I'm interested in adding to to my diagnostic options. Picking up vibration sources and misfire detection/confirmation of cylinder identification are my main interests. I don't think I'm at the skill level to look at valve events via the intake pulses. This would be my first pressure probe, I have no experience with tranducers or pressure probes of any kind.


https://www.aeswave.com/FirstLook-Engine-Diagnostic-Pulse-Sensor-p8618.html



Has anyone used this in the field with real world success? Does it make your life easier, or sit in the box? I've read about people building their own, but I find limited details on doing so. Any feedback is appreciated.

 

[Sommech7498]

I’d be interested in this as well.

I recently built my own pressure Sensor from a pressure transducer, 5 v regulator, and plastic project box from amazon. Use it to do in cylinder pressure waveforms to see valve events, compression buildup, exhaust pressures, intake vacuum, etc. it’s extremely easy to make and paired with a decent scope (preferably pico as they let you make custom probes that do the math for you for the voltage to psi conversions) you can do quite a bit of engine diagnostics that you really can’t do any other way outside of disassembling the engine.

What I’m not really sure of is what a pulse sensor would excel at that a standard pressure transducer would. The transducer I bought goes to about 20ish PSI vacuum and is very sensitive so I’m not sure what advantage the pulse sensor has for plotting intake vacuum waveforms. I haven’t tried using it in the exhaust but I’d imagine it would be able to detect exhaust pulses.

I’m sure someone mich more knowledgeable about this stuff will be able to explain what advantages a pulse sensor has over the standard pressure transducers. I’d definitely be interested in trying to make one if there is an advantage that I am just not seeing.

 

[2ndGearRubber]

Pico is likely in my future. I do want it to work with my ol' gen 1 modis, which I have no doubt it will.

My interest over a dedicated pressure transducer, is vibration detection, (and cost). Connect stethoscope end to Piezo-electric sensor. Output vibration, ie: sound, as voltage/frequency. Confirm which pulley, wheel bearing, ball joint is the noise maker, objectively. No echos, no opinions, just data. Really any noise making component could be inspected, as well as rattle locations, etc.

A transducer should be sensitive enough to do exhaust pulse captures, although without spending big bucks, I'm not sure the cheap ones are fast enough at picking up the minor fluctuations. If you have details of what transducer you bought, I'd be interested. Building a cheap one is something I'd be interested in as well. I don't think I'd use it enough to justify a pico or top of the line option.



Where did you get your pico from? 4425? Any insights; how does it compare to other scopes you've used?

 

[Sommech7498]

That makes sense. Didn’t think of the stethoscope/noise and vibration aspect. I might look into making one now that you say that.

As for the transducer I bought.....

https://www.amazon.com/dp/B00NIK900K/?tag=atomicindus08-20

I’ll be at my shop either tomorrow or Monday to pick up some stuff and I’ll take pictures of how I made it and post it here. Super simple and cheap. I think all I’m everything cost me less than $50.


As for the pico itself, I bought mine from sealing.com I don’t remember exactly why I picked them but I believe they were the best priced at the time. I had no issues with them and they seem to be a quality company

I only got the 2 channel scope though unfortunately I believe 4225 is the model. I’d definitely recommend the 4 channel but unfortunately I pushed my budget just to get the 2 channel and couldn’t afford the 4 at the time. But the scope itself it awesome. The zoom capabilities after you’ve stopped recording is top notch IMO compared to the Snapon stuff I’ve used. I also love the rotation rulers when doing things like in cylinder pressure waveforms. Being able to set up 180,360,540, and 720 marks and see TDC and BDC of each stroke is extremely handy. Also comes in handy if doing cam/crank correlations or any timing related readings. The custom probe features are great if you plan on using aftermarket clamps, probes, and sensors. Let’s you adjust your probes and does all conversions for you so you can get accurate measurements without having to pay for the pico probes and clamps.

I would definitely recommend the 4425 if you can spend the money. It’s absolutely great once you play around for a little bit and figure out all the little features

 

[Sommech7498]

Here is a couple pictures of the pressure transducer I made. I made it on a home made PCB board but that is not needed. Can be done with wires just as easily. I just had a couple extra laying around as well as the PCB mounted 5V regulator.

Basically I just used a couple alligator clips and wire that run to the battery on whatever you’re working on(can be replaced with 9V and a switch). That turns on the 5v regulator. Then the output wire on the 5v regulator and ground wire go to the pressure transducer as the reference wire and ground for the sensor. Then the transducer output wire and ground wire go to the input of the labscope. I used some banana jacks that attach right to my picoscope leads. All shoved into a plastic project box I bought off amazon. The transducer itself I attached to a standard air tool fitting. That connects right to a compression tester hose with or without a schrader valve depending on what you want to do.

It’s not the prettiest tool but works great and is super cheap. I forgot to boot up my laptop and show a couple pics of the waveforms I’ve caught so far. I’ll try to do that Monday if I can remember.

 

[2ndGearRubber]

Thanks for posting that. I'll look into the required parts for that.