Cylinder contribution

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Burt_100
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Cylinder contribution

Post by Burt_100 » Sun Jul 28, 2019 10:09 am

I recently seen a video of the tech measuring cylinder contribution using the ckp sensor and a current clamp to reference cylinder, it seamed very interesting but he didnt say how to set it up or what it actually tells him other than it shows if a cylinder is contributing more or less due to crankshaft rotation speed, can anyone explain;
a; how to set it up or refer to a guide on setup
b; the value in the test and how to interpret the waveform

Thanks in advance

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hexibot43
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Re: Cylinder contribution

Post by hexibot43 » Sun Jul 28, 2019 9:50 pm

I believe there is a built it relative compression test based on that setup built into the picoscope diagnostic software. It has everything to help you run that test. It is one of the tests I've just added to my initial tests. Verify soundness of engine mechanical . Check it out.

ben.martins
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Re: Cylinder contribution

Post by ben.martins » Sun Jul 28, 2019 10:53 pm

Hello Burt_100,

Thank you for your post and I think what you are referring to is the Crank maths function.

I will follow this up tomorrow with some more information but for the time being please see this link which describes the Math in more detail.

https://www.picoauto.com/support/topic11511.html

I hope this helps

Kind regards

Ben

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hexibot43
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Re: Cylinder contribution

Post by hexibot43 » Mon Jul 29, 2019 3:53 am

https://www.picoauto.com/library/automotive-guided-tests/diesel/
Perhaps you want more of what Burt 100 was listing.

It was strange the page on this website for the petrol version of the test I was suggesting was missing. But that is a link to the diesel version. I would think this would give you simple quick good data. With the addition of a timing event, like ckp sensor, or a firing of an injector, or coil you would be able to connect to timing of cylinders. This is a non running test. And gives information of the mechanical engine. It will only produce data while cranking.

I would be curious if there was the ability to see true cylinder contribution of a running engine. Measuring acceleration of crank? As is done with misfire detection.

ben.martins
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Re: Cylinder contribution

Post by ben.martins » Mon Jul 29, 2019 7:54 am

Hello Burt_100 and Hexibot43,

I think the following video will help.
Practical Pico - Cylinder identification and relative compression on CRD engines

This was from our first ever Practical Pico session so I apologise for the quality, we were in the early days! The link I've attached starts at the point where we are looking at misfire detection using the Crank Maths function and how to determine cylinder contribution based on crank acceleration.

I hope this helps and please let me know if you need further assistance.

Kind regards

Ben

Iver
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Re: Cylinder contribution

Post by Iver » Fri Aug 23, 2019 9:13 am

I would be curious if there was the ability to see true cylinder contribution of a running engine. Measuring acceleration of crank? As is done with misfire detection.
It can be done very well and there are threads in this forum showing that. The tiny little downside is the missing tooth on the phase wheel that produces a annoying dropout.

I have an abs wheel mounted on a pole with a Sensor mounted above that I rest on the Fan Belt which eliminates that. Also saves the B*llache of looking for the ECU or CKP
Last edited by Iver on Sun Aug 25, 2019 5:43 pm, edited 1 time in total.

s4c
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Re: Cylinder contribution

Post by s4c » Sun Aug 25, 2019 3:28 am

Iver

Do you have a picture of your setup?

Regards

Iver
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Re: Cylinder contribution

Post by Iver » Sun Aug 25, 2019 5:46 pm

I don't have mine with me here. Not at work until Tuesday.

But it looks like this.This is just a crude drawing but you will get the idea.
abs wheel.jpg
I got an Engineer to Lathe down a Plastic block so that the Ring could be tightly pressed onto it and glued. Next he pressed and glued a small bearing into the centre of the plastic.
Bearing Delete.JPG
Bearing Delete.JPG (11.04 KiB) Viewed 330 times
.

A thin alloy strip is bolted to the bearing as a handle and an old position sensor mounted securely to the alloy strip.
Then just hold it down on any part of the fan / aux belt.

Pico should build and sell one.

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