Strange first time in cylinder pressure waveform?
- Robbocop33
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I'm using correct 500psi setting in scope.
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"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right.
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- Robbocop33
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If that fails i'll try your second suggestion,thanks for replying!Lee.
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Looks like you've got way too much time on the screen. That could be killing the sampling rate. Knock it down to 1 second and see how that looks.
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"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right.
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- Robbocop33
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I'll maybe try a 2v scale tomorrow and see how that goes.
I just made up a transducer and lead as described somewhere on this forum,at least it's working in some way,just not the correct way!
I just couldn't justify the price of a genuine snap-on transducer just now,been buying lots of tools,machines for key cutting/programming.
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Robbocop33 wrote: I just made up a transducer and lead as described somewhere on this forum
That was, likely, a thread started by Noah. I'm sure he'll chime in, when he logs in.
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right.
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Robbocop33 wrote: I also tried doing it on a 5v scale and it never picked up a trace.
Did you try that with it connected to one of the 'scopes voltage inputs? Probably won't show a voltage trace from the transducer input.
And have you checked for a Schrader yet? That waveform really looks like it could be caused by one.
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- Robbocop33
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Regarding schrader,that completely slipped my mind,i'll have to check that,oops!
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www.scannerdanner.com/forum/diagnostic-t...-transducer.html#859
When you get the schrader valve out of there, I'd be curious to see if you can verify the accuracy of the pressure scale.
My particular sensor does not coincide with the pressure scale and on the Verus Edge, if you aren't using that preset, you can't use the 9 pin for power and ground.
For those reasons I abandoned the 9pin in favor of power and ground via USB.
What sensor did you go with? Looks like it provides pretty good resolution compared to some of the ones I tried.
"Ground cannot be checked with a 10mm socket"
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- Robbocop33
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I will report back with exact transducer etc i used later today once i've removed schrader and retested later today.
I have actually bought the proper Snap-on adapter lead so you can use two transducers at the same time,so i am probably going to buy a proper snap-on transducer some day,i was just in the frame of mind what the hell,i'll try a cheap version first!!
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- Robbocop33
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I removed the pressure relief valve,plugged it up and to my knowledge there aren't any restrictions now from plug hole to the Verus.
I'm still getting the same waveform above??I've tried every setting possible!!It's so frustrating.
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- Robbocop33
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Here's a pic of what im screwing into the spark plug hole.I'm pretty sure everyone who is going to do their first in-cylinder scope test will just turn round and grab a hose off a standard compression tester they may have and think it will work?
A lot of people probably don't expect this problem.I might just drill it out then blow out the debrus.
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- Robbocop33
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I bought a hollow brass tube that screws into the spark plug hole,then just screwed in my cheap Chinese 500psi transducer to the top of it.
Scope trace is good,just slight noise in the trace,only thing is now you can't really do much with it ,regarding resizing it,blowing it up and diagnosing it!,which really makes me want a picoscope now!! ;-)too busy at the moment buying tools for key cutting/programming which i've also been learning about.
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If you would care to share a picture of the waveform with us, I would like to see it.
You may not need the Pico just yet, you can squeeze a bit more out of the Verus.
Try setting the time base much lower.
It will look like garbage until you pause the capture, then press the zoom button (magnifying glass in the bottom right corner). That will zoom all the way out on the pattern. From there you can zoom in and out until you get one or two repeating events on the screen.
You can then drag your two vertical cursors around.
I've even seen someone turn on a second chanel just to have a horizontal line on the screen as another cursor.
You can also try a/c coupling the waveform. It's going to throw the voltage scale scale off, but without some more testing, you probably won't have an exact pressure to voltage conversion yet any way.
"Ground cannot be checked with a 10mm socket"
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- Robbocop33
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