Compression tests - Conventional vs. Labscope
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- Опубліковано 31 гру 2018
- Brandon Steckler compares two tests in this recording.
One being the conventional method of compression testing vs. a more modern version called relative compression testing.
When beginning your diagnostic approach on any diagnostic routine, it is always best to develop a route to travel early in the game.
One early step in that approach when diagnosing a misfire should include a relative compression test. This test is non-invasive, very quick and powerful.
We want to know early on if we suspect there may be a mechanical failure or not before performing more invasive tests.
Thanks for watching!
Brandon, Keith & Ivan all together in one workshop - lucky customers :)
It's funny watching Keith run back and forth in the back...lol.
Excellent demonstration Brandon, thanks tbt for putting this info out there. It took me months to prove to my shop that rc is trustworthy. Id have to do it conventional just for them to feel comfortable with rc testing. Now they don't bother, i print the waveform, and they don't question, ever 🤣
Wow, my Jeep made it into the video LOL What a freaking amazing time with you guys! Can't wait to do it again!Brandon, great job on that video.
Thought that was you in the background.
Love Brandon's teaching style!
He's a rockstar indeed. I would recommend yall to attend a class of his live! One of the best in the industry in my opinion - Brian Culotta
Nice job Brandon. Complete explanation without wasted time like so many other UA-cam posters, including professionals. I am retired from 45 years as a technician and love to keep up with what is going on in the trade.
I appreciate you taking the time to watch and for your feedback
A million thanks for all of the feedback. Thank you all for investing the time to watch.
To answer a few questions, the RC Test, monitoring for voltage-drop is almost as accurate as current measurement. The difference in reliability is minimal.
I recommend applying this test to a known-good vehicle. Then, try removing a spark plug (to create low-compression in one cylinder) and repeat the test. There is NO BETTER WAY TO LEARN this valuable technique! I use it EVERYDAY 👍
No, thank you for taking the time to teach us. As someone else mentioned, I thought a RC test could only be performed with an amp clamp. Have an awesome year!
Hi Brandon
I am motor nechanic for over 50 odd years (15 years in Europe, rest here in Adelaide, South Australia. Still have opportunity to learn a lot. Thanks for posting it. Time watching new techniques is time well spend.
George - QQMR
This was so professional , that Brandon even said AFFIX . I like it 💙
I was at a shop for a different problem and I overheard another mechanic was bitching about removing the intake to do a compression test so I did a RC test and found he didn't have a compression problem he was so impressed he gave me $100 dollar bill!!
Great job Brandon
PHENOMENAL!!!
I had no idea you could do a relative compression test with a scope without an amp clamp! Great stuff right here - thanks for that one, Brandon! AC coupling right at the battery - I'd have never thought of that. 👍👍
Noticed Keith and Ivan making cameos in the background there - now that's a garage people will want to bring their modern, computer-controlled problem-children to. 😎
Happy New Year guys! 🍻
So five years later i hit on this vlog, if that garage is yours and u own it top man, if that garage aint yours and you work there they aint paying you enough and your talent is wasted, great vlog great explanation , you have a great easy way to explain things that is instantly understandable, brilliant vlog...
I am learning so much off this guy. Cant say i can keep up that easy , so i watch the video a few times for my slow brain. Fantastic explanations , very impressed! Thank you
Good testing/procedure and as usual, "knowledge is power" and being efficient in this field is very KEY! Time management guys.
Thank God for all of you guys out there sharing your knowledge and experience with all of us!!!!
Super helpful ! Wow ! Such an outstanding tutorial ! Extraordinary detail !! You provide precise coaching cues for us to do the procedure ; AND , include all the other pertinent information - namely, the “who , what , where, when , why, and how !! I’m learning lots from you ! Thanks mate !!
🙌🏼
Great video and it's so simple. I like the low hanging fruit concept. It's funny because when I saw Brandon's face I knew it was a video that I would learn something. This guy knows and knows how to explain the fine working details. I'm one of those people that has to fully know why I'm doing something before I will use it even though it's a popular test Brandon breaks it down
Quality video...everything explained well. I only recently realised that you could use voltage instead of ampage...thanks for showing us
Nice Diagnostic procedure, GREAT way to start off 2019 with Time saving accurate Diagnostics. This is a Perfect way to nail or eliminate one of the funnels I always talk about ( The Engine Integrity Funnel )
Another tip I like to employ that is equally as valuable as AC coupling, is to invert the scope leads on the battery, this will allow it to appear like a conventional RC test with an amp clamp.
L1 Automotive Diagnostics and Programming LLC good tip will try this
I wouldn't, potential for blowing your scope if its connected to ground some how such as when connected to a mains powered laptop as you're effectively creating a short through the scope.
Battery powered not as risky.
Safest bet just use the invert function.
Excellent Video !
I always use the relative compression test. Quick and accurate test. Most important time !!
An extremely well made video! Extremely professional and very well spoken! You are an asset to your professional, Brandon. All you NY guys (Eric O., Keith, Eric and more) are top-tier professionals! I am now a subscriber!
Cool video! I never thought to use voltage drop for a relative compression test! I appreciate the clear and concise explanation! Thanks!
9:50 was my favorite part. Shows Brandon as a true professional
Why what happened?
@@TrainedbyTechs he only quick smirked even though I walked by mooning him . 😏
@@NewLevelAuto 🤣😂🤣
haha he actually did I was there xDDD
Great job. Brandon is knocking another diagnostic strategy out of the park with a wealth of information.
Great video guys
This guy is a great teacher and very precise
I would let him work on my trucks anytime. And I’m Looking for more vids by him. Hope he has several
Kevin, thanks so much. I work with a great group of guys @Trained By Techs and it’s a tremendous team effort.
We will have plenty more instructional videos to come 👍
So you AC couple it to get a "zoom".
Thank you so much!!! You don't know how much that helps me. I bought a low amp probe for my verus long ago mostly for relative compression but when it arrived the clamp was way too small to fit on battery cables. I tried doing it by measuring battery voltage drop but at 20v setting there was literally zero detail. I couldn't get any detail no matter what settings I tried and Snap On only sells a new style low amp probe that literally feels like a $20 Chinese probe I ain't paying $500 CAD for it. Can't wait to try this.
Excellent video as always Brandon! The power of the scope cannot be underestimated. Been playing with a pulse sensor recently and all of the opportunities it presents.
The light bulb went off when you moved the cursor to zoom. I have a verus edge and I thought the zoom was useless. Thanks clearing that up !!!
Thanks for taking the time to present this. Great job.
This guy is good! Thanks for taking the time! 👍
Very well explained as usual. Thanks for taking the time to make it.
Thank you Brandon. Good job. Have a blessed and safe New Year to you and your family.
Thanks Brandon. Had your class at Super Saturday 2018 and I thoroughly enjoyed it!
Brandon, great video with excellent information hope to see more videos from you, Happy new year and cheeeeers
Excellent demonstration, good information and very easy to follow
Another excellent demonstration on using the scope to do a relative compression test.
Finally the man behind the articles. lol
Read some of your stuff on motor age magazine and its always a pleasure.
Thank You Brandon for taking the time to teach and helping out the industry..
Thank You,
I can’t tell you how much we appreciate the feedback. It’s a good feeling, to know my articles are helpful.
VERY good presentation. I’m Impressed 👍
Brandon, that was an AWESOME video on compression testing. Now I really want to see a relative compression waveform on your Civic with a 20psi loss on cyl2...would that show up on the scope? Also we have to do a follow-up vid on Keith's van, since it actually DOES have a mechanical engine problem than the relative comp test didn't definitively show :) I have the vacuum Pico waveforms here for reference.
It was so much fun hanging out with you and Chris and Keith on the Island, we should do that again sometime soon! Happy New Year!!
Yep Me too! I definetely want to see a compression waveform from the civic wich has 20 some PSI difference in relation to other cylinders...
Most-definitely...lets pool our collected data and I will do a follow-up video-post
Best I have seen, professional demonstration
Great video Brandon 😀. Planning on watching your tst webinar 😎
Awesome video Brandon.
Very good presentation, thanks for taking the time!
Thanks so much for the positive feedback. Stay-tuned as we will have another video coming in a few weeks👍
Awesome video,,,very detailed. Many thanks for sharing your knowledge and taking your time to help others wanting to learn the correct way of using a scope. Big thumbs up....
Thank u Brandon. Can't wait to attend ur class in jersey for tst this month. Have a blessed day and a happy new year. All the big dogs in one shop. Wow😃😃😃
Fantastic explanation! I'm looking forward to Brandon's classes! Even vocally, he articulates so well! Check out Brandon's article in Dec Motor Age Magazine "The Importance of Asking Why...."
Thanks Cuba , appreciate the support ❤️
Great presentation. Great video.
Thank you, James
👍 thanks for sharing! Please keep it up.
Thanks Brandon great video
SUBSTANTIAL Trained by Techs
Brandon Steckler
Tutorial brilliant video amazing from the start to finish loved it thank you very much Brandon Steckler Trained by Techs
From Nick Ayivor from London England UK 🇬🇧
Thanks for the great explanation and video. Always used the amp clamp but next time I'm going to try AC coupling.
Good job Brandon !
Thank you for the video👍👍👍
Very nice Präsentation - thanks for Sharing !
Keith's walking around a lot in the background, someone get him a coffee! Lol nice video Brandon! Super professional!
Thank you!
excellent video amigo thank you for you time and explaint
AWESOME video ,Brandon, Thank you for the effort to illuminate us all, 🙂👍, what else is there to say except, 'lets go BRANDON' 🤥, BLESS 😇
Great job on the video
Definitely a time saver!
Awesomeness! Thank you so much Brandon, I can't afford a new clamp at the moment, I always thought too ya needed to clamp battery wire. Thanks again.
Awesome video.
I love it when I learn new stuff. Fantastic video! I don't know why, but I just didn't consider voltage drop instead of current. 35 years I've been doing this. Duh-huh. Thank you.
AWESOME! This is exactly why we share! So many have helped us, early in our careers and we wish to pay it forward
great video.thanks
You did a great job explaining the steps while working. Your pretty talented. (Even with Ivan and Keith messing with you, you continued on!
😆..I love those clowns, great friends
With all my respect to your experience
Cylinder Compression test is an accumulative way of testing, some service info specify the number of piston strokes/revolutions to record the reading some do not mention anything, therefore it is essentially an accumulative testing so no matter how many compression strokes you go with, the air pressure inside to combustion chamber, the hose, and the gauge eventually gonna equalize on a definite Psi reading.
Thank you for the great video
Excellent video Brandon. I see Keith Defazio walking around in the background. 👍
Yes, I had to give him a lollipop just to get him to sit still😆
Thanks for the share.
This tech is truly a professional technician. I never even knew that conventional compression tests with the snap on compression testers with shrader valves can cause that... I guess i would've misdiagnosed then...
Thanks for the video.
If you are used to use the current clamp while testing relative compression you might want to invert the trace so the peaks of the signature align with the compression humps.....
Or you can put your positive probe on the engine block and the ground probe on battery negative while you are DC-coupled in the 1 voltrange, makesfor a really good signature
Invert the probes....that is simple and brilliant! Awesome tip. Will try that next time :)
Great video! Was a bit distracted with the thought” who does he look like”. Then realized a young Sly Stallone. Yo Adrian😄
Thanks for that
Very good
Lo interesante es que lo hiciste sin usar una pinza amperometrica al positivo del burro de arranque. Poner en AC el osciloscopio para la medida al borne negativo de bateria. Ingenioso. Felicitaciones
Wow excellent more vids plz
THANKS, More on the way! Anything you’d like to know more about?
amazing
Pretty good video;.
Dustin, thanks brother 👍
Relative compression test definitely the way to go, I’d love to see a relative compression test on the civic ... great video 👍
Better than that...I challenge you to try it yourself, on a known-good vehicle.
Capture/post and tag me in it...tell us all what the test has shown you 👍
Brandon Steckler I see what you’ve done there and I like it, it shows how professional and committed you guys are to teach us 👍... unfortunately I don’t own a scope but I’m setting some goals for 2019 and a pico scope is one of them hopefully soon ... cheers
You be sure to let us know how we can help you move forward
You are not off the hook yet, though… When you get your scope, I still expect your capture/post 😬
Brandon wow! Invaluable lessons. I got a bit lost with the ac coupler. If you can explain
Nice video and very well explained. It's a shame you didn't do the relative compression test on the first vehicule. It would have been nice to see if the relative compression test would have caught the weak cylinder that showed up in the conventional test and just how much difference would have shown up on the trace.
Hey Michael,
You bring about a great point. The terminology “relative” obviously referred to how each current-peak relates to the next. Because is inferre s “starter-Load”, minor/normal variations in compression won’t make much of an effect on the current-trace. However, when there is enough of a shift in compression-differential to cause a drivability-symptom, my experience has been that the evidence is clear. Try it yourself, by loosening a single spark plug to simulate compression loss👍
@@brandonsteckler3417
Brandon, I was trying to find out if anyone had ever tied the two tests together. In other words would a 10% reduction in compression over the companion cylinders show up in a relative compression test, OR would it take 20, 30, or 40 percent before you'd see the difference on a relative compression trace? I was looking for the cutoff number?
I would assume it’s based upon the the vertical-resolution of the scope and would also take an accurate/responsive supplemental-voltage support, to maintain the accuracy of the test
I believe on the ATS E Scan Elite , you can do a relative compression test , in SECONDS at the OBD2 connector . As well as a Volumetric Efficiency Test , etc. What about when you have to remove an intake plenum just to gain access , as well as risk breaking plugs , frozen plugs or baked on boots ? This could be done on the Snap On MT-2400 - about 25 years ago , with an amp clamp !
That dam ambulance/fire truck
is that kieth using a bosh broom at 12.53 in the video ? and was ivin there showing him how to use it ? ha ha great video brandon
This was awesome thank you. I didn’t realize you don’t need an amp clamp just postitve and neg on the batter. What did you have that channel set as?
Thanks for the input and I’m glad we could assist you 👍
Brandon good job Amico mio, you have a high ability to transfer information said by a foreigner!!!
Armando, my friend! Thanks for tuning in. We’ll get together one of these days!
Thanks for the feedback!
great video. i'd loose the long hose on that mechanical guage
You should also add, if you haven't. What happens when you take something apart and something gets damaged.
Jesse, so true. Thanks for bringing that point up👍
Great video!!
AC coupling filters out the DC signal portion. I understand using AC coupling when testing AC ripple on an alternator (AC source) to block out the DC voltage to increase the image resolution on a scope.
However I am a bit confused on how AC coupling is working in the video: relative compression case while we are using the starter's voltage drop (DC signal). The starter's commutator strips also generating AC ripple while it's revolving, no?
Can someone dumb it down and explain how this actually works with AC couple/capacitor feature when it comes to relative compression?
Thanks for the reply Mike. AC Coupling will remove the DC from the circuit and simply show the "change" in voltage. Everytime a piston approaches TDC, the voltage will naturally drop due to the load on the circuit. AC coupling allows the scale of the tool to be much smaller (1-2v) which allows the drops in voltage to be more pronounced in appearance. Effectively creating a "zoom" feature.
Brandon you are the man. Thanks for the explanation!
Surely,
Typically we view waveforms as reference to ground.When we view an AC signal, we think of it as one that varies above and below the ground line (meaning positive and negative). This is a true statement but it would be more accurate to say “an AC signal is one that varies above and below the reference point.
When we AC Couple a Waveform, we make the reference point the average point or center of the waveform (not ground). If we then place the scope in a lower voltage range, we can view variations above and below the reference point (the average of Waveform. This technique serves as a ZOOM function. This works well on scopes that don’t possess great zoom capabilities.
Does this make sense?
Thank you Brandon Steckler! Very well explained! I'm just wondering if Voltage drop test is as accurate as current drop test since voltage and current have different reaction times (problably not a considerably difference to set a noticeable difference at low cranking RPM tests) Just wondering.
Yes, the vdrop Test will yield you similar results as the amperage-test. Close enough to make a sound determination of a mechanical fault
Voltage drop and current flow are proportional to one another. In fact, You You place the both on the same scope, they are mirror images of one another , just inversely proportional
This is great information. Thanks. Question... Would the traditional compression test work with the schroeder valve removed? I didn't quite understand that.
Brandon : I appreciate your time and knowledge . There is a company called Auto Ditex in Bulgaria that makes several diagnostic items , including a relative compression tester . It clips to the battery . The test can be unsynched or synched to ID each cylinder . It is a low skill level . I saw Diagnose Dan use it . There is also discussion on Scanner Danners channel . It costs $ 290.00 on E Bay , plus shipping . I don't know if a single channel U Scope from AES Wave can do this . But wouldn't you need the a second channel to synch the cylinders ? Again , thanks for the lesson . Bill .
Bill, this is true. To sync the RC test, a second channel is needed.
easy to grab low hanging fruit..great info
Wouls have been great to see the labscope on the Honda to see if it picked up the weak cylinder that the conventional test saw. Maybe next time?
I thought that was new level and pine hollow milling around in the back ground. Looks like some serious discussion was going on. Kieth seemed a little agitated.
Lucky shop to have the big guns helping them.
Would about hooking up an amp clamp on the battery and a vacuum transducer on the purge line to check the camshaft and lifter integrity? Thoughts?
Damn, I just cringe thinking about weak hood props and a hood crashing down on a new Snap On Zeus while I'm inside cranking over the starter. I think a quick go -no go relative compression test with volt leads could be done right inside car, off a DLC Line SPI. I'm too lazy to bother hooking to a primary wire of coil for a trigger unless I see a smaller dip somewhere between humps to justify wire piercing for a trigger to determine which one has a compression deficit .
Yes! Thank you for pointing that out. Anywhere there is access to source voltage/Ground can be utilized.
The DLC is a great place to sample, right from the driver’s seat. You make the valid point of capturing a sync only if a fault is detected. It definitely saves time not to find a sync unless necessary.
I appreciate your help, thank you!
Now this is the kind of extra info I love
It’s only about 7 minutes to remove that intake, which I think is cheap insurance to assure nothing is missed. On one occasion (on that same 3.6 motor) I’ve personally seen a relative test show nothing really out of the ordinary; the engine sounded totally normal while cranking and even ran great from a cold start with no misfires running up, yet there was 60% leakage through the exhaust valve on the misfiring cylinder. I’d like to know what your next step would be, if spark, fuel and relative test are all good..
What exactly is ac coupling and in what applications is it used
Brian Culotta HOW CAN I PURCHASE YOUR TEACHING CLASSES ON VIDEO IF I CAN NOT ATTEND AND THANK YOU FOR YOUR TIME .
Lmfao Keith in the backround. EDIT: And Ivan haha
I'm planning to start offering a RC test as part of a marine survey on boats. Plugs can be near impossible to access on some boats. Would you recommend to always do the RC test on a warmed up engine? Or as simple of a test as it is, maybe one test cold and then one hot...Might reveal more info
Thanks, you can clearly see the value in the test. Most-often the faults it reveals can be seen when the engine is cold. However, there could certainly be situation ms that arise where a mechanical fault will surface when an engine comes to operating temp. My advice...test under the conditions the “symptom” is present 👍
Hello mr Brandon what would happens with the waveform if the engine has a wet spark plug by oil thanks a lot for an answer
Hi, Great question. The key to successful and efficient diagnostics is understanding the limitation of the tools/tests being utilized. The relative-compression test (voltage-drop or amperage) simply displays the the load placed upon the starter as each piston, in-turn , completes a compression stroke. So long as the cylinder fills/seals similar to the other and has the similar stroke, the load should be the same.
To answer your question, simply having oil on the spark plug means oil consumption is present but not necessarily a loss in compression. Does this make sense ?
Awesome info!! I tried this on a Vantage. I chose lab scope dc volts, 1 volt scale and 2 sec time, then pushed the a/c coupling button. No pattern! Maybe i should chose 4 channel instead of dc volts? Maybe I'm just not recording properly? I a'm watching the vidio for the third time. I will try again tomorrow.
Next day....i got it! Awesome test, thanks!
Awesome! Yes, the test comes in very handy. The best part....it’s quick/easy , yields a ton of data and can be applied to virtually all DC-motor started engines👍