PicoScope Basics: Relative Compression Testing
Relative compression testing is a great way to check for the mechanical viability of an engine in many diagnostic scenarios. In this video, we explore the basics of setting up and conducting the test using PicoScope equipment, and toward the end compare a handheld OTC Oscilloscope's function. To simulate a fault, I also remove a spark plug and set a reference trigger using an ignition event for cylinder number one. This video should useful for getting started with relative compression testing for any new, beginning or curious technician.
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Components in the video:
- PicoScope 4223 2-CH Automotive Diagnostic Oscilloscope (PP502)
- PicoScope 600A Inductive Clamp
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Пікірлер: 33
Thank you Adam. Good job. Have a blessed and safe week to you and your family.
@AdamsAnalysis
3 жыл бұрын
Thanks, you too!
Really appreciate the run down. For anyone else trying to watch this and study for the ASE A1 - the answer they're looking for is put the clamp on the positive wire going to the starter. I'm not saying the negative is wrong - that's just what the ASE is looking for.
@AdamsAnalysis
Жыл бұрын
Thanks for watching and adding to the discussion.
Very clear and helpful. Thanks a lot
@AdamsAnalysis
2 жыл бұрын
Glad it was helpful!
Fantastic informative video thanks 👍
good clear demonstration, thanks
@AdamsAnalysis
3 жыл бұрын
Thank you for watching!
Just what I wanted to see .. you are a winner
@AdamsAnalysis
2 жыл бұрын
Thanks for watching!
KNOWLEDGEABLE Adam 's Analysis Tutorial very helpful 👌👏 👍thank you Adam 's Analysis From Nick Ayivor from London England UK 🇬🇧
Thank you ❤
Great video on relative compression test. It can indicate many failure modes that will not show on a scanner b/c of mechanical failure. In my opinion, best to use a fuel injector to identify a cylinder and then follow firing order. Too many older engines have wasted spark ignition on mirrored cylinders, so its a 50/50 guess on which cylinder to check for more diagnostics. Again, great video
i have the hantek cc-65 amp clamp, will that work if i set it right?
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Much appreciate your time, but unplugging the fuel pump fuse is more easier? Or depends?. Thank you so much
@AdamsAnalysis
2 жыл бұрын
It really depends. On some vehicles it is a quick process to remove the fuel pump fuse. Many vehicles might tie in other systems to that same circuit. As a process, I review the electrical diagram and look for the quickest and easiest process.
@Mohy.ly87
2 жыл бұрын
@@AdamsAnalysis bless you 🙏
@kirkbrown2147
2 ай бұрын
Or remove the starter relay and crank it there
Way to go adam
@AdamsAnalysis
8 ай бұрын
Thanks!
How does an electronic amperage test tell you anything about cylinder mechanical compression tho? I thought your wave form there only demonstrated spark (and combustion?) Or is the combustion itself signaling compression?
@AdamsAnalysis
2 жыл бұрын
When compressions is present, the starter motor must work harder to continue rotating the engine. With an amp clamp, we can see these rises in current usage and equate them to compression events.
@gigostackkfmawi9263
2 жыл бұрын
@@AdamsAnalysis thx this is really helpful and useful info.
So this test gives no actual compression read in terms of psi/kpa? But a wave form of "compression/ignition" (in amps?) That is used to give a relative idea of the entire compression state?
@AdamsAnalysis
2 жыл бұрын
That is right, the test provides no actual compression data. The reading shows us how each cylinder is performing relative to another. It is a quick test help us understand if a misfire is compression related.
@deeznutz3494
Жыл бұрын
If I can hear/feel a limp while cranking, what is this test telling me that I don’t already know? At that point, I’m doing a compression test on all cylinders followed by a leakage test to get a full health report on that engine, to assure nothing is missed. I’m sure glad all these scopes weren’t around, and they weren’t shoving this garbage down our throats way back when I went to school
nice i have an ampclamp but not like this one ,KAIWEETS KC 601
Very expensive test ! picoscope + laptop .. the itester carscope is better and faster 🙂
If I can hear/feel a limp while cranking, what is this test telling me that I don’t already know? At that point, I’m doing a compression test on all cylinders followed by a leakage test to get a full health report on that engine, to assure nothing is missed. I’m sure glad all these scopes weren’t around, and they weren’t shoving this garbage down our throats way back when I went to school
@AdamsAnalysis
Жыл бұрын
To answer your question, adding a cylinder sync will help identify the specific cylinder with a fault. This would eliminate the need to do a compression test on all cylinders, saving time. A scope is just another tool. Sometimes it’s a good choice, sometimes not. The freedom of process during diagnostics is something I enjoy about working on cars. I’m always trying to learn new things and become more accurate and efficient. I encourage my students to do the same. Thanks for watching.
@morganwhite7750
8 ай бұрын
One of the benefits to a relative compression test is that you will have a better overall picture of what's going on in the engine, versus a conventional compression gauge with a Schrader valve will show you only peak compression number. Also on a 6 or 8 cylinder engine the rc compression test could save you a couple hours time with a non intrusive test, instead of removing all the coils and checking compression 1 by 1 .