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Home made in cylinder transducer

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02 Sep 2020 02:33 #42711 by Hardtopdr2
Replied by Hardtopdr2 on topic Home made in cylinder transducer
Could just be carbon buildup on the intake side of valves due to the backpressure pushing back into intake with the plugged cat. Time for some seafoam or pop intake off and clean intake runners and valve ports with some cleaner.
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02 Sep 2020 08:24 #42712 by Noah
Replied by Noah on topic Home made in cylinder transducer

Is it possible that the air filter was/is coming apart and restricting the airflow?
I once experienced this on a Ford F150 where the plastic cone came off the filter. The car would bog down on heavy accelerating/WOT as the cone was sucked into and blocking off the air.

The air filter looks to be brand new-ish.
There was this bit of under britches integrated into the lid of the filter housing assembly.


And there were some leaves in the bottom of the box, pre filter, but I don't think either one explains the change in symptoms.
It still barely ran with all of that off the car until I gave the throttle a right boot work out.

I returned said under britches to it's place in the filter box and it still runs just the same.

-Seems to me that I could live my life, a lot better than I think I am.
I guess that's why call me The Working Man.-
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02 Sep 2020 08:29 #42713 by Noah
Replied by Noah on topic Home made in cylinder transducer

Atta boy Noah, awesome diag. Looks like you were up against a couple of issues and came out ahead. Tell your Boss to put the old Cat in and take her for a ride!! He'll come back and thank you!

Nice Work,

Paul


Thank you Paul, it still doesn't feel like a win though.
Many unanswered questions...

As for the boss, I'm not interested in convincing anyone at the shop. I find that when I'm doubted, the universe has a way of eventually delivering my vindication.

-Seems to me that I could live my life, a lot better than I think I am.
I guess that's why call me The Working Man.-

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02 Sep 2020 11:39 #42715 by Matt T
Replied by Matt T on topic Home made in cylinder transducer

Many unanswered questions...


One quick thing you could do is have a look for camshaft position PIDs. Might tell us whether the cam timing is screwed up or something the PCM is doing.

Another would be to put a transducer in the O2 sensor bung to see if there are any pressure pulses which could be affecting the in cylinder waveform. Best to do this with another transducer in cylinder but if you don't have two of them an ignition sync would be good enough.

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11 Sep 2020 12:53 - 11 Sep 2020 12:55 #42976 by al514
Replied by al514 on topic Home made in cylinder transducer
So you connected both power and ground from the USB cable and then connected the scope to the ground at the sensor to monitor the signal? I've been building my own pick ups and sensors so I have to try this. Can you draw up a little diagram, if not too much trouble.
Last edit: 11 Sep 2020 12:55 by al514. Reason: Added
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11 Sep 2020 14:16 - 11 Sep 2020 14:25 #42980 by John Curtis
Replied by John Curtis on topic Home made in cylinder transducer
The EVO is advanced, but it's closing almost on time. This to me can be an indicator of valves out of adjustment. A tailpipe waveform tailpipe waveform along with the in-cylinder could confirm this. But the opening early with the spike does look like an advanced cam. Pretty nice capture with that sensor.

Making Pressure Differential Sensors (PDA Sensors) for pressure pulse diagnostics.
Currently servicing Central Texas.
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11 Sep 2020 15:08 #42986 by Matt T
Replied by Matt T on topic Home made in cylinder transducer

So you connected both power and ground from the USB cable and then connected the scope to the ground at the sensor to monitor the signal? I've been building my own pick ups and sensors so I have to try this. Can you draw up a little diagram, if not too much trouble.


If you've got a 3 wire transducer you give it 5v power and 0v from the USB and scope the signal wire. There's some discussion on whether or not to also tie the USB 0v to scope ground earlier in the thread.
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12 Sep 2020 07:37 #43003 by Noah
Replied by Noah on topic Home made in cylinder transducer

So you connected both power and ground from the USB cable and then connected the scope to the ground at the sensor to monitor the signal? I've been building my own pick ups and sensors so I have to try this. Can you draw up a little diagram, if not too much trouble.


It's very simple. The sensor is 3 wires. It wants 5v and ground to operate, the USB port is capable of delivering this power and ground.
(Matt T is wise to be apprehensive about sourcing this power and from the scope. I haven't hurt anything yet and don't think I will, but the possibility can't be over looked!)
The third wire on the sensor goes to channel one on the scope. Done.
I don't even hook up a ground lead to the scope every time, but when I do it's to the car, not the sensor ground. I honestly haven't tried using the sensor ground.

-Seems to me that I could live my life, a lot better than I think I am.
I guess that's why call me The Working Man.-

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12 Sep 2020 07:41 #43004 by Noah
Replied by Noah on topic Home made in cylinder transducer

The EVO is advanced, but it's closing almost on time. This to me can be an indicator of valves out of adjustment. A tailpipe waveform tailpipe waveform along with the in-cylinder could confirm this. But the opening early with the spike does look like an advanced cam. Pretty nice capture with that sensor.

Thank you for your insight! Now that the power has been restored, I haven't been afforded the opportunity for much follow up testing. I do have some test drive scan data that isn't very revealing (vvt PIDs don't respond, I'm told that's a common snap on thing with toyota).
I'm very pleased with the waveform that sensor produces. I bought 3 sensors on Amazon thinking they would be better but the resolution doesn't even come close.

-Seems to me that I could live my life, a lot better than I think I am.
I guess that's why call me The Working Man.-

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28 Jun 2021 15:38 #49674 by VizoEdward
Replied by VizoEdward on topic Home made in cylinder transducer
I am powering my home made transducer from a 5v USB portable charger from a battery pack. Use it on a SO Vantage pro. It does work well with the transducer voltage signal plugged into the selected channel be it #1 or # 2. So far only use one channel at a time. Would I be able to input an additional signal (like an ignition event for example) through the other scope channel ?. Will the scope react nasty to this setup due to the feed/grounds being source separate. One from the USB the other from the vehicle battery?. I have done the setup with two separate DVOM both sharing a common ground with no apparent issue. But the DVOM's have higher impedance than the VP. Please if any opinion. itwill be apreciated Thanks

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02 Jul 2021 07:25 #49749 by Noah
Replied by Noah on topic Home made in cylinder transducer
You should have no trouble using the second channel for an ignition synch or just about anything else for that matter.
I frequently use mine with more than one channel.

-Seems to me that I could live my life, a lot better than I think I am.
I guess that's why call me The Working Man.-

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02 Jul 2021 16:24 #49754 by al514
Replied by al514 on topic Home made in cylinder transducer
So I've made a couple of diy pressure transducers with a 5volt ref box to power it and a bnc to the scope. I've found the linear equation to set up a custom probe that another tech had figured out. It works really well, except that at 0psi I'm reading about 1.6psi. I'm wondering what methods others are using for the custom probe set up. Obviously I need to change the equation alittle to get it to read 0. Using a look up table wouldn't go into a vacuum if I remember correctly when doing incylinder testing.

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04 Jul 2021 08:57 #49789 by Noah
Replied by Noah on topic Home made in cylinder transducer
With the Snap On scope there is no custom probe set up and the transducer presets don't work well with the refrigerant pressure sensor I use.
I bench tested mine with a vacuum hand pump and a cylinder leak down tester, and just wrote down the voltage to pressure correlation.
It's pretty linear from what I recall. Most of the time when I do use the transducer, I'm less worried about the actual pressure and more interested in the shape of the waveform.

-Seems to me that I could live my life, a lot better than I think I am.
I guess that's why call me The Working Man.-

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04 Jul 2021 13:57 #49796 by al514
Replied by al514 on topic Home made in cylinder transducer
Oh I'm using a pico scope, guess I should have mentioned that. I'm wondering if I change the linear equation alittle I can get my pressure reading to zero. I'm only bringing it up because on an incylinder test I want to be able to see the condition of the cat. I know a really bad cat will give a huge spike 180° in, but I'd like to see more accurately than being 1.5-2° off.

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07 Jul 2021 03:30 - 27 Aug 2021 16:30 #49869 by RosBaig
Replied by RosBaig on topic Home made in cylinder transducer
Hi....A GM tank sensor likely works superior for deplete beats. On the off chance that you supplant GM fuel pumps it is beautiful simple to choose one up since the modern pumps more often than not have a modern sensor. If they are troublesome to come by I have a part and may send you a couple. A Outline sesnsor will work for vacuum either will require either employing a 9V batt or setting up a 5v supply.

www.7pcb.com/
Last edit: 27 Aug 2021 16:30 by RosBaig.

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08 Jul 2021 11:50 #49892 by al514
Replied by al514 on topic Home made in cylinder transducer
The setup I have works really well, it's a 300psi transducer, and measures vacuum if the correct calculation is put into pico custom probe settings. I just need to figure out how to lower the setting by 2 psi. That's all

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08 Jul 2021 14:01 #49897 by Matt T
Replied by Matt T on topic Home made in cylinder transducer

The setup I have works really well, it's a 300psi transducer, and measures vacuum if the correct calculation is put into pico custom probe settings. I just need to figure out how to lower the setting by 2 psi. That's all
 


Try using a lookup table. Numbers I threw in are guesses for a 300 PSIA 0-5 V transducer. You'll have to adjust the voltages in the table to match your transducer. Also bear in mind that if you do have an absolute transducer the PSIG zero will drift around a bit due to changes in barometric pressure.

 
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