WPS500X vs snap on EEPV302AT Pressure transducers

Has anyone had any luck with the Snapon 500psi transducer? Model EEPV302AT? Of course everything about the WPS500X looks better but it's the difference between $500 for the Snapon kit and $1000 for the PP939 kit for the WPS500X. The diagnostic tool budget is always tight...

I've only used the Snapon one before but it's a shop tool. So I haven't had much of a chance to play with it. Just in and out usage on shop time. There are a few things I don't like about it.

Firstly It would be nice if it came with its own hoses and adapters...

Secondly, captures seem to be pretty noisy and not very clean on the Snapon transducer.

I also don't really trust the scaling... I went through the calibration process but on compression captures I get vacuum readings of -20psi. That's below 0PSIA! So unless that engine is producing dark energy I'm pretty sure it's not calibrating properly..?


I'd mainly be using the Snapon Verus. Snapon scopes use a shared ground reference. So if I use a WPS500X would it be susceptible to noise from the shared ground? Like if I were also grabbing captures from things like injectors and coils?

The extra $500 is significant so it'd be nice to get the cheaper Snapon transducer if it gets me by. Then again I'd hate to make that kind of investment to only later wish I had spent the extra money....

I guess what it boils down to is the Snapon transducer is definitely fine for comparing cylinders. Looking for bad apples, etc. But if you want to scrutinize individual detail, (signs of leakage, valve openings, etc) do you pretty much need the WPS500X..?

Pressure -- vacuum gauges in imperial/US units usually have scales in PSI above zero (ambient atmospheric) ) and inches hg below atmospheric I wonder if this what is going on here.

Easy way to check is to do a sanity test against shop air pressure above atmospheric and a vacuum pump with gauge for sub-atmospheric.

Andy.MacFadyen wrote: Pressure -- vacuum gauges in imperial/US units usually have scales in PSI above zero (ambient atmospheric) ) and inches hg below atmospheric I wonder if this what is going on here.

Who in their right mind would make a pressure transducer automatically convert everything below atmosphere into inches of mercury yet the whole scale is in psi??? That would be dumb! Oh wait... This is Snapon we're talking about... I could see them doing something like that!

As funny as that would be I don't think that's the case. I went over a capture I have on here and the exhaust plateau is at -12psi. So if the whole waveform is shifted down by 12 or 13 psi then that would make the largest vacuum reading of -23psi actually be -10psi. Which would put it around 20inHg which is a sensible reading.

The thing I've heard about the Snap-On transducers is zeroing issues, which in turn makes detailed analysis difficult. I'm also not sure the Snappy has the same kind of detail and response time as the WPS. I've also seen the WPS used for pressure pulse (intake/exhaust/crankcase) testing with pretty good results, but I'm not sure the Snappy can do the same.