adding math channel

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adding math channel

Postby wellspin » Tue May 02, 2017 8:30 pm

Had my new diagnostic toy a while now,a 3223 certainly a very nice piece of kit.
I tried the pico diagnostics cylinder balance with mixed results,still a work in progress I think.
This led me to using the math channel for misfire detection.I have played with this feature using the equation (A,36) and (A.60),the car is a 2001 renault scenic 1.6 16 valve petrol.My results seem different to what I was expecting.
Ive attached an RPM capture from the car,can somebody apply the math channel and maybe add some data, comments etc
cheers
Ian :)
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test 21.psdata
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wellspin
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Re: adding math channel

Postby victor2k » Tue May 02, 2017 9:34 pm

Hello,
Why the amplitude of your signal is only 10mV(15-18PP)?
Something in your setup is wrong.
Please make a new capture with a misfire event recorded.
Best regards
victor2k
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Re: adding math channel

Postby Datchet Diagnostics » Tue May 02, 2017 10:48 pm

I note that the capture was gathered with the scope channel set to AC. Although these inductive position sensors do output a AC signal they are best measured with the Pico set to DC and the black lead directly secured to battery minus. AC coupling this particular measurement has a potential to hide some critical data obscuring your process.
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Re: adding math channel

Postby wellspin » Sun May 07, 2017 2:33 pm

It was taken using a x10 probe,looking at the specs I realise that something is a miss with wiring or the ecu possibly.
ill do some checks and report back
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Re: adding math channel

Postby Ben Martins » Mon May 15, 2017 12:45 pm

As Victor2k has said I think there is something not right in your setup. You shouldn't need to change the probe to x10 for crank signal. If you're looking for a misfire it would be worth using the other channel you have available as well. Maths channels can be utilised better when you have more information. Getting the setup right in the first place is always key. As a general rule of thumb for measuring vehicle circuits we use the 20/20 rule which means ±20 V and 20 ms/div. This is really useful if you're dealing with sensors that you are unsure of output voltages.
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