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Home made in cylinder transducer
2 years 9 months ago #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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2 years 9 months ago #49897
by Matt T
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.
Ā
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
Ā
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.
Ā
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2 years 9 months ago #49941
by al514
Replied by al514 on topic Home made in cylinder transducer
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This is the Linear equation I used for the 300psi transducer so I could use it for incylinder. That way I can see the vacuum pockets, it's just about 1.8psi off. I just need it to read zero at atmosphere. I can see incylinder waveforms with this equation great. I watched a video about setting the custom probes using a look up table with a 5 volt sensor, and it instructed to want to set your 0 psi at 0.5v and your max psi at 4.5v. Here's the video about that. I set my 80psi transducer by this and it compensates for atmospheric pressure I guess is the reasoning behind it
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2 years 1 month ago #54887
by Noah
"Ground cannot be checked with a 10mm socket"
Replied by Noah on topic Home made in cylinder transducer
I'm still playing with these, just wanted to share an update for anyone interested.
Really my only complaint using salvaged pressure sensors is the lack of accurate voltage to psi scaling.
I recently discovered that the oil pressure sensor on Chrysler 3.6l V6 engines is just about a perfect 1-1 scale using the 100psi transducer setting on Snap-On scopes.
When bench tested against a trusted gauge I never saw more than a 3psi variance up to 100psi on the Verus Edge and Vantage Pro scope.
And, bonus, since I can use the transducer preset, now I can power the sensor with the appropriate AUX connector on the scope and not the USB port. (The aux power source is only switched "on" when selecting a preset that requires it, so on voltage scale the transducers need a different 5v power source)
I have changed a handful of the oil filter housings on these engines under the intake manifold (mostly Grand Cherokees and Chrysler 300s) and decided to harvest the pressure sensors.
It's a pretty common issue so chances are if you're in an independent repair shop, you'll have a chance to score one no charge.
Really my only complaint using salvaged pressure sensors is the lack of accurate voltage to psi scaling.
I recently discovered that the oil pressure sensor on Chrysler 3.6l V6 engines is just about a perfect 1-1 scale using the 100psi transducer setting on Snap-On scopes.
When bench tested against a trusted gauge I never saw more than a 3psi variance up to 100psi on the Verus Edge and Vantage Pro scope.
And, bonus, since I can use the transducer preset, now I can power the sensor with the appropriate AUX connector on the scope and not the USB port. (The aux power source is only switched "on" when selecting a preset that requires it, so on voltage scale the transducers need a different 5v power source)
I have changed a handful of the oil filter housings on these engines under the intake manifold (mostly Grand Cherokees and Chrysler 300s) and decided to harvest the pressure sensors.
It's a pretty common issue so chances are if you're in an independent repair shop, you'll have a chance to score one no charge.
"Ground cannot be checked with a 10mm socket"
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2 years 1 month ago #54888
by juergen.scholl
An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.
Replied by juergen.scholl on topic Home made in cylinder transducer
Thank you Noah for this interesting update. Two questions here:
- Did you take a scope capture of both the pressure reading and the signal voltage as such at the same time?
- Do you happen to know the range/ max. pressure this sensor is capable; does it work with snap throttle acceleration reaching the 300 psi region?
- Did you take a scope capture of both the pressure reading and the signal voltage as such at the same time?
- Do you happen to know the range/ max. pressure this sensor is capable; does it work with snap throttle acceleration reaching the 300 psi region?
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2 years 1 month ago #54889
by Noah
"Ground cannot be checked with a 10mm socket"
Replied by Noah on topic Home made in cylinder transducer
I was looking for a picture to upload, but I guess I didn't save one. If I have downtime today I will post a picture.
I am however doubtful that it will be capable of reflecting pressure of the magnitude you mention.
I have yet to try it in a cylinder, but even if it's not an appropriate sensor for in cylinder testing, it will still be useful for other testing such as oil pressure and perhaps fuel pressure.
I am however doubtful that it will be capable of reflecting pressure of the magnitude you mention.
I have yet to try it in a cylinder, but even if it's not an appropriate sensor for in cylinder testing, it will still be useful for other testing such as oil pressure and perhaps fuel pressure.
"Ground cannot be checked with a 10mm socket"
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2 years 1 month ago #54890
by Matt T
Since the sensor works with a 0-100psi scale it's probably putting out at least 4 volts at 100psi. It uses a 5V supply so the voltage isn't available to get anywhere near 300psi. The output will likely be clipped at 5V somewhere around 120psi.
Replied by Matt T on topic Home made in cylinder transducer
- Do you happen to know the range/ max. pressure this sensor is capable; does it work with snap throttle acceleration reaching the 300 psi region?
Since the sensor works with a 0-100psi scale it's probably putting out at least 4 volts at 100psi. It uses a 5V supply so the voltage isn't available to get anywhere near 300psi. The output will likely be clipped at 5V somewhere around 120psi.
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2 years 1 month ago #54911
by juergen.scholl
An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.
Replied by juergen.scholl on topic Home made in cylinder transducer
I understand your reasoning. Voltage and pressure readings would confirm the sensor's operating span/correlation. It still may be the 100 psi range limiting a higher reading.
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2 years 1 month ago #54927
by Noah
"Ground cannot be checked with a 10mm socket"
Replied by Noah on topic Home made in cylinder transducer
"Ground cannot be checked with a 10mm socket"
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2 years 1 month ago #54933
by Noah
"Ground cannot be checked with a 10mm socket"
Replied by Noah on topic Home made in cylinder transducer
That was plugged into my cylinder leak down tester, from high pressure to low.
Max is about 100psi @ 4.5v
Min about 0.3psi @ 0.5v
Max is about 100psi @ 4.5v
Min about 0.3psi @ 0.5v
"Ground cannot be checked with a 10mm socket"
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2 years 1 month ago - 2 years 1 month ago #54934
by juergen.scholl
This confirms pretty much Matt's assumption about the operating range.
P.S. You really like this picture, donĀ“t you?:woohoo:
An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.
Replied by juergen.scholl on topic Home made in cylinder transducer
That was plugged into my cylinder leak down tester, from high pressure to low.
Max is about 100psi @ 4.5v
Min about 0.3psi @ 0.5v
This confirms pretty much Matt's assumption about the operating range.
P.S. You really like this picture, donĀ“t you?:woohoo:
An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.
Last edit: 2 years 1 month ago by juergen.scholl.
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2 years 1 month ago #54951
by Noah
"Ground cannot be checked with a 10mm socket"
Replied by Noah on topic Home made in cylinder transducer
lol, I'm more impressed at how easy it was to save a BMP right from the Vantage pro to a USB stick and upload the image.
"Ground cannot be checked with a 10mm socket"
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