Re:Re:Re:APT-100 Pressure Transducer

Got to play with the new APT-100 a bit more. After the last post, I had a few concerns about the in-cylinder captures. So for a direct comparison, I hooked up the APT-100 to the #1 cylinder (red) and the good ol' Fluke PV350 to #4 (green). The conversion values are a different between the two transducers - The APT-100 is set for 1V/100 PSI (or 10mV/PSI), while the PV350 is set for 1mV/PSI. That's why there's a difference in scales. Cranking compression first:



APT is showing right at 116 PSI. Again. But the PV350 says otherwise:



Flukie says 166 PSI, which I find to be much more reasonable. Interestingly, if you take 1.16V, change that to 1160 mV and figure 1mV/kPa, you get to 168 PSI. :silly: Not sure if that's a coincidence or not.

Anyway, I tried some running compression waveforms as well. Turned the scales down for more detail.



#1 definitely doesn't look right. Leaning compression towers, decompression pocket doesn't reach full vacuum, and the exhaust plateau is missing detail compared to the PV350 (which has a filter applied).

So maybe there's leakage in the hose or adapter, right? Nope, I got it to hold vacuum with a hand pump. Maybe that cylinder really is leaking? Moved the PV350 to #1 and got good waveforms. What the hell. :blink:

Tried the same setup on my '15 Equinox and the problem got even worse:



You don't have to be an expert to know something's wrong here. Aside from the transducer itself, the only thing I can figure is there's something wrong with the provided compression hose. :huh: The APT-100 uses a different style (Foster? Honestly don't know) connection than most compression testers (Milton M-style). That means I can't use any of my existing compression hoses, or swap hoses between transducers for test purposes.

Maybe the included hose just sucks? :lol: Juergen had mentioned the APT-100 benefitting from a stiffer hose. As always, any thoughts you have are welcome!

Tyler,

when I got my APT 100 the passage within the brass portion of provided hose was bad/clogged and caused erratic results. After drilling it out it performed much better.

Nevertheless I changed the interface/coupler on the transducer itself so I can work now with any standard compression hose.

juergen.scholl wrote:

when I got my APT 100 the passage within the brass portion of provided hose was bad/clogged and caused erratic results. After drilling it out it performed much better.

I was thinking it looked like a restriction/snubber between the cylinder and transducer was at least part of the problem.

Regards the kPa looking peak pressures see what the thing reads with a known shop air pressure. Then you'll know whether you've got a kPa unit or not.

when I got my APT 100 the passage within the brass portion of provided hose was bad/clogged and caused erratic results. After drilling it out it performed much better.

Interesting. :huh: I'll have a look at mine tomorrow.

Nevertheless I changed the interface/coupler on the transducer itself so I can work now with any standard compression hose.

Definitely going to do that. Do you happen to have a link to the coupler you're using? While I'm at it, I'll probably buy a sacrificial compression hose to use for intake pulse testing.

Regards the kPa looking peak pressures see what the thing reads with a known shop air pressure. Then you'll know whether you've got a kPa unit or not.

Another excellent idea.

Ended up stealing the hose coupler off the PV350 and an adapter out of my OTC oil pressure test set. Now we're free to use normal compression hoses.



Back in #1 on the Sentra, the cranking compression is closer to what I was seeing with the PV350:



My whole kPa scale idea is out - 1,550 kPa converts to 224 PSI. :lol: 155 PSI is much closer to the 166 the PV350 was reporting. The running compression still isn't perfect...



I'd do another direct comparison capture, but I scavenged the coupler off the PV350 to make the APT work. :silly: I'll get another coupler and follow up later.

I'm looking to up my transducer game, but I think that also is going to me uppingy scope game, lol.
Looks like a quality tool.

Noah wrote:

I'm looking to up my transducer game, but I think that also is going to me uppingy scope game, lol.
Looks like a quality tool.

Coming from the guy that makes his own transducers? I think your scope and transducer game is fine just fine.

I got around to comparing the adapted APT-100 and the PV350 in another known good engine. This time it's an '11 Kia Sportage 2.4L. Cranking first:



The rulers show these two reading within a few PSI of each other. Good enough for me. Now running:



The APT compression tower still seems to be leaning/asymmetric.

I also had the chance to try the APT on a known blown head gasket. '08 Equinox 3.4L. APT in red on the coolant bottle, sync on #6 in green:



The way this sensor behaves is noticeably different than other head gasket captures I've taken with normal pressure pulse sensors . There's the building of pressure (which is a red flag by itself), AND there's enough detail to tell which cylinder is blown:



Firing order is 1-2-3-4-5-6. The pressure rises in the cooling system immediately after #2 compression.

All in all, I'm pretty satisfied. For the price. :silly: It's not perfect, and it needs some modification out of the box to make it useable. But the capabilities are there, and the price is right.

Well I was having a hard time deciding on the apt-100 or the wps500x... my cheap side won and I ordered the apt-100. I'll let you know how mine works out of the box when it makes its trip from china.

Also way off topic for this thread but I see your still using the autel, I bought there newest 1 last year (without scope module as I already had there mp408 scope)(turns out not compatible) but I don't love there data vs snapon... what erks me the most is some pids can't be graphed.... and there graphs aren't all that good... anyways all this to say how has your transition gone?

Ben wrote:

Well I was having a hard time deciding on the apt-100 or the wps500x... my cheap side won and I ordered the apt-100. I'll let you know how mine works out of the box when it makes its trip from china.

Congrats! Mine took about two weeks to arrive from the mainland. Let me know how it treats you.

Ben wrote:

Also way off topic for this thread but I see your still using the autel, I bought there newest 1 last year (without scope module as I already had there mp408 scope)(turns out not compatible) but I don't love there data vs snapon... what erks me the most is some pids can't be graphed.... and there graphs aren't all that good... anyways all this to say how has your transition gone?

Overall? I'm still very happy with mine. Going on two years now. Wouldn't hesitate to buy one again. Well, maybe I'd wait a year for the price to go down. :blush: Definitely took the place of my Snap-On as the go-to tool.

Maybe I'll start another thread? I love the Ultra, but it's far from perfect. :lol: I'd love to hear your thoughts.

Here are a couple of WPS and APT measurements taken simultaneously. The APT signal for some reason lags slightly behind the WPS one. With lower pressure, as occurs under idle conditions, the APT reads slightly less - 5 to 7 psi - when compared to the WPS. This difference diminishes as the absolute pressure rises.The overall waveforms do look like twins.

The set up:

The APT reads 10mV for 1 psi.....

Well it showed up yesterday! Without a battery.... so I jumped on Amazon to order a button less 18650 because my regular 18650s didn't fit (who knew there were different length 18650s....) anyway it theyvarrived today so straight to the charger it goes! In the mean time I looked at the hose and decided it did in fact need drilled out so into the lath to get a nice centered drill hole and about 3/4 inch in the brass fitting broke off.... soooo time to replace the stupid coupler they come with and switch to automotive style.. I'll let you know how that goes when I get there. BTW did you need any special fittings to connect air coupler?

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Ben wrote:

Well it showed up yesterday! Without a battery...

So came mine, official reason being lithium battery transport is soooooo dangerous :dry: Nevertheless you can testdrive it with just the usb charger connected.

Ben wrote:

BTW did you need any special fittings to connect air coupler?

No, I did not. Straight forward job.

Ben wrote:

Well it showed up yesterday! Without a battery.... so I jumped on Amazon to order a button less 18650 because my regular 18650s didn't fit (who knew there were different length 18650s....) anyway it theyvarrived today so straight to the charger it goes!

Ah yeah, it's like Juergen said with battery shipping. For anyone else considering an APT-100, I bought this set on Amazon:

www.amazon.com/dp/B06ZZ8Y89F

In the mean time I looked at the hose and decided it did in fact need drilled out so into the lath to get a nice centered drill hole and about 3/4 inch in the brass fitting broke off.... soooo time to replace the stupid coupler they come with and switch to automotive style..

:lol: Figures.

I'll let you know how that goes when I get there. BTW did you need any special fittings to connect air coupler?

I'll see if I can figure out which fitting I used... Stole it out of my oil pressure test set.

EDIT: Pretty sure that's a 3/8-18 NPT male to 1/8-27 NPT female fitting.

Haven't had a chance to use it yet, I did get it changed to some nice high flow connectors though. I've been working on a tailpipe adapter without much luck, im looking to do something like ATS tailpipe venturi but apparently that is harder to design without seeing the insides of 1 then I guessed because my test today was a fail

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Ben wrote:

Haven't had a chance to use it yet, I did get it changed to some nice high flow connectors though. I've been working on a tailpipe adapter without much luck, im looking to do something like ATS tailpipe venturi but apparently that is harder to design without seeing the insides of 1 then I guessed because my test today was a fail

The tailpipe venturi from the E-Misfire kit? Never thought about trying to duplicate that. :huh: I was thinking about trying to do something like the Jarhead Diagnostics exhaust adapter for pressure pulse sensors:

www.jarheaddiag.com/shop/p/jarhead-diagnostics-exhaust-hose

Yup that's the 1, the idea behind it is you only get the pulse from the drawback of air after the misfire with little to no noise from the rest of the pulses, I did make 1 of the spring hoses last year but I've never cared for the tailpipe pulse sensor with engine running (I haven't messed with it enough to be able tpnspot it quickly)

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Ben wrote:

I've been working on a tailpipe adapter without much luck, im looking to do something like ATS tailpipe venturi but apparently that is harder to design without seeing the insides of 1 then I guessed because my test today was a fail

The patents will help you copy it :lol: I've attached the first one. There are two more but they don't add much besides a screen for laminar flow.

Judging by the "prior art" Bernie had to invent this thing because he couldn't figure out how to use a piezo :lol: :silly: :lol:

Ben wrote:

I did make 1 of the spring hoses last year but I've never cared for the tailpipe pulse sensor with engine running

My piezo did a lot better sitting on the ground instead of hanging off the tailpipe. 1/4" brake line and 3/16" thinwall rubber tubing. IIRC Chad uses a mic stand for his

Matt digging up patent documents. :blink: :woohoo:

APT made quick work of a 5.7L Hemi with a suspected worn intake cam lobe. Misfiring cylinder in red, known good cylinder in blue/teal/whatever: