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Jumped timing chain (no compression on 3 cylinders) - GM 3.6

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Anyone looking for information on checking engine timing with a scope, look no further! I have the opportunity to show several different methods of testing on this Buick with a chain problem, and how you can be confident in your call. We also get to see another variable with the relative compression test, which can bite you if you’re not careful.
Engine Performance Diagnostics chapter 1
Symptoms
- crank no start
- spark and fuel present
- no excessive exhaust backpressure
Fix
- corrected the jumped timing chain
Tests shown
- how to listen for compression during cranking
- how to use an incandescent test light to check for spark
- performing a relative compression test with an ignition sync
- analyzing relative compression waveforms for timing issues
- using a lab scope to check cam/crank relationship
- using an in-cylinder pressure transducer
- how to perform a cranking vacuum test by covering the throttle body
- analyzing cam/crank waveforms in detail
Tools used
- PicoScope 4425 4 Channel Standard Diagnostic Kit
www.aeswave.com...
- WPS500X Pressure Transducer Kit
www.aeswave.com...
- Inductive High Amp Current Probe
www.aeswave.com...
Playlist
- (Chapter 1) Misfire ID, Compression Tests, Vacuum Leaks, Fuel Trim, Head Gasket, Restricted Exhaust, Low Power, DMM
• (Chapter 1) Misfire ID...
Related videos
- Honda Civic 1.7L starts, runs, stalls (incorrect timing belt installation)
• Honda Civic 1.7L start...
- How to identify a broken timing chain - GM 2.2 (part 1)
• How to identify a brok...
- How to check for a jumped timing chain or belt
• How to check for a jum...
- How to perform a compression test with a scope (Verus-Vantage)
• How to perform a compr...
For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium www.scannerdan... There is a 14 day free trial.
On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!
Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC.

Опубликовано:

22 авг 2024

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Комментарии : 264

@shermanbird3248 3 года назад

Just saw this video for the first time.... feel compelled to share thus: I learned back in 1972 to use a 10 dollar Cal-Van vacuum gauge for my first engine diagnosis by my mentor, a Rolls Royce Master. That lesson, through the years, has kept me from shedding many frustration tears, except when I've strayed from basics! It even cost me a job when I worked at Cadillac in the 70's because we had a prima donna driveability guy who thought the way to cure a misfire was to rev the hell out of the engine! He had a Sun Interregator at his disposal and he never hooked up the vacuum gauge to any of the cars he was charged with fixing. I love your videos! Keep up the great work! I showed him how to diagnose an internal idle air bypass with a vacuum gauge. He had fought this car's rough idle for days. My intent was to help, but his ego was bruised, and me being an upstart kid got the boot!

@pitchforkpeasant6219 Год назад

In the words of marky mark, ego is not your amigo. Think i just lost a job over it. Really wanted to move to texas too☹️

@andrewwilson8317 6 лет назад

I have watched this video a couple of times and really learned from it. There are some very important technique points raised and need to e learned from. Jumping to conclusions is easy, anybody can do it but the importance of not doing that and getting the facts straight is everything! The importance of data comparison is vital. Asking yourself" how is what I see different from know good reference data?" Is vital. Knowing where to look and what to look at saves so much time money and effort. Anybody who claims they can diagnose a fault like this by eye without getting the data and analysing it properly is either an engine whisperer or a fool! Get the data, analyse it, confirm it and get it right, first time.

@campen777 11 лет назад

Wish polititions were like you ... When you miss somthing or make a mistake you have the balls and honesty to tell us . That gives us faith and trust in you .. I'm from the uk but think you should run for president .keep up the good work .

@Mr39036ce 6 лет назад

I can't help but look at this and think all the money mechanics charge for repairs are so worth it! Part wrench and part tech and engineer.I am an electronics technician and aloy of the scope material you present is great.Being a carburetor and point-gap guy I have to replay stuff to see how it is applied to an engine.For the most part,I get it.Have built a few motors in my day and am pretty handy with a wre ch.

@ScannerDanner 11 лет назад

thanks man. you are so right. these techniques take a lot of time to talk about but are so fast to use. and at times more accurate than any old school test you can do.

@steveguest8028 6 лет назад

Thanks Paul,it’s so easy to get misled or confused in this game what with so many different engine configurations etc,I must admit when you cranked over this engine at the start of the video it didn’t sound at all like it had missing compressions to me either and I’ve been a tech for 30 yrs so it just goes to show that you can take nothing for granted....brilliant diagnosis by the way....Many Thanks 👍🏻

@shameelali2549 10 лет назад

Awesome work Paul,for the guys that don't understand or are scared of using a scope,Dan is a teacher,yer you could of done it a different way,but sometimes you gotta do it this way too,also for us and his class as a demo on rel comp he could of found the problem in no time at all how ever making a vid in front of a class takes much more time,i watch your vids every night while iam relaxing as iam a tech in australia love your work brother

@ScannerDanner 10 лет назад

Thank you Shameel

@markferraro5250 6 лет назад

I love this video I remember watching it about 4years ago it will keep you a out of the rabbit hole. One thing I would like to add is the crankcase waveform over the dipstick tube barring you don't have a piston ring issue on all six pistons the waveform is solid as far as peaks and valleys in this case the relative comp showed 3 peaks in 2 crank revs the crankcase will always show 6 even with a jumped timing chain or a total loss of compression as if you removed all spark plugs great video SD

@pitchforkpeasant6219 Год назад

Amazed more people don’t seem to watch these videos. Cant fix a problem if you cant figure out the cause of the problem. Unless you fire the parts shotgun and a piece of the shot actually hits the cause so to speak. And ive seen plenty of cases to almost call it a rarity. Cant get enough of these videos. At worst they give a different perspective 👍😁👍

@ScannerDanner Год назад

Thank you!

@ScannerDanner 11 лет назад

you are missing the point. you cannot always use conventional testing methods to ID these kinds of problems. on some engines you cannot get to the rear spark plugs without removing the intake! how are you going to verify no compression or a jumped chain on this design without intake removal! what if you remove the intake and you are wrong in your assumption? what I am trying to do, as I said in the video, is to develop other testing methods, to add "tools to our tool box".

@frankbarr6267 3 года назад

Just got done doing compression tests on a 2003 3.8 dodge caravan and had exactly that problem no compression on 135 and i was like WHF . So now ive got to figure jumped chain . thanks for the video gives me a point to start with

@natemoncur9333 3 года назад

Please this isn’t a sales pitch🤣😂 got me cracking up. Appreciate these videos. I’m a self taught mechanic and use your videos to learn the things I need to to solve problems on my personal and friends and family vehicles. Thanks

@henryrobinson9837 5 лет назад

knowledge is the resultant of learning,your in a new field it will take time to master the quirks of the advanced engine designs,with them changing every 2-5 years

@ScannerDanner 11 лет назад

This is just the order that I teach my class. I will come back to it next. Thanks!

@mrpistonrecaro6483 3 года назад

I’m going through this issue right now. Codes p009 p0008 p0016 p0017 p0018. Cleared codes and they come back. Issues. Runs rough. Checked compression and bank 2 2-4-6 have 150psi. Bank 1 1-3-5 have 200psi. I’m opening the valve covers to see what’s messed up. Thanks for showing us something new.

@scotthooper5127 6 лет назад

The sound was even because of the firing order, 1-2-3-4-5-6. Every other cylinder was good, thats why you didn't hear a problem. Had the firing order been different, you may have been more apt to notice right away. I am loving this guys brain! Holy s&^t he's smart!

@martyisabeliever 11 лет назад

Hey Brother Paul good to hear from ya! Another great instructional.. Thanks for your time... Lord Bless you and yours as always...

@davek6630 2 года назад

Great video! I just experienced this on my own 2013 Impala, with 190k. Car ran perfect, when driven last. Went to start it the next morning 15deg outside and it wouldn’t start. No codes, good fuel pressure and spark, I pulled the front plugs and checked compression 95/85/90 on the front bank. I pulled the intake and checked the rear60/20/35. 😢

@MMCTUNING 2 года назад

Thank you for the video! Good job! Yes, ''V'' motors are sometimes confusing when diagnosing.

@rrmech11 11 лет назад

hey paul good point about cranking vacuum always look forward to your videos

@budd1814 8 лет назад

Thanks for the insight...... enjoyed the smart board. (sometimes I don't see the forest for the trees)

@jacobnbr11 11 лет назад

I have learned that the sound of relative is not always accurate especially VCT engines. I seen a tech once that was going to sell a 5.4 ford engine based on relative sound when I walked over and did a clear flood to get the engine to start. That was a good eye on the relative humps, never seen one like that but I will store that in my memory for future. Thanks Paul

@PhillipBailey 8 лет назад

Excellent! I could see how not adding the sync during the relative compression test could throw you off.

@ScannerDanner 11 лет назад

that is correct my friend. we didn't though because of the difficulty in accessing the 1 rear cylinder you can get to. The other two are under the manifold. plus, going into this job and by the way it sounded to me, I never suspected 3 dead holes. it truly wasn't even on my radar for a while.....my fault for sure

@sivucit 11 лет назад

Hi, I agree with Paul. Knowledge is the power. If you are smart, you should learn both ways (old school and Modern techniques), based on your experience, you should either one(old school or Modern) to resolve it.. What Paul is doing is explaining in details to every one of us.. If he don't want to explain may be he can do things very quickly but that is not his intention.. when u explain to newbie it take hell lot of time.. hope u got my point

@ScannerDanner 11 лет назад

I do not think the variable cam mechanism would cause the chain to be off to the point that it would cause a no compression problem. but it is a great question and something that would be checked more closely when the timing covers were removed.

@GSRThree 11 лет назад

Thanks for another great video. I had one of these in the shop today and used your bank 2 wave form for my known good. My case was different though mine would run but was dumping raw fuel out of the exhaust. bank 1 intake cam jumped. I am an L1 Master also but still consult your videos and book frequently. Your doing an awesome job keep it up!

@ScannerDanner 11 лет назад

no, it is very common to only have one cam sensor. and on this one I would say yes, the multiple cam sensors is used for control and diagnosis of the variable valve timing

@karimjedda2154 11 лет назад

Hi Paul,Here in Tunisia I have found some electronic dealer who told me that he could deliver me the kits at the international price HT.Till now I should wait for half a month to get the kits.You know here it is not possible to buy online. I verified the price that was almost unique for all websites (I have visited).I hope that I have well done.Just I want to tell you that I have seen very cheap chineese automotive PC based labscope, but I was not confident in it. thank you Paul.

@DustinBigMac 9 лет назад

Your better at using the smart board then my teachers in high school lol

@theoldwizard998 11 лет назад

Just additional FYI. The wide and tall crank pulse is likely from a "missing" tooth on the crank wheel. It is not broken, but missing by design to show a reference point on the crank. Some system do "double fire" (fire plugs as pairs, one on compression, one on exhaust) until enough revolutions have occurred to be 100% certain that the cam and crank signals are properly synchronized.. Another reason to use crankshaft position sensor for reference while doing test during cranking.

@bric2661 11 лет назад

Another great video Paul, thanks for sharing it with us, I bought your ebook a few weeks ago it's the least I could do. All the best from the UK

@ILiekFudge 11 лет назад

Thank you for the good info. One dead hole or a head gasket between cylinders is easy to hear. Can you post an update once it is torn down?

@j.j.springer1099 6 лет назад

this is our problem thankyou. my son and his buddy were pulling there hair out

@frankjohn4302 10 месяцев назад

Great video Danner.Thanks

@michaelwitmer7536 3 года назад

When I first saw the relative comp. test I just thought it was a waste spark that we were seeing. It would have got me!

@rickwest2818 3 года назад

I thought exactly the same thing.

@paulsimpson2232 6 лет назад

This SD is very interesting material, and puts away forward for me to tackle a problem i have at the monent. My concern and little disappointment is that you use a pico to show us this and not a verus, i appreciate its your choice. Not many of us have both , and like me i brought the verus , it would be nice if you can do this with verus one day. But if you have already have can you drop me link please. Thanks for all your work you do . It is alot to take in and fit in with a working day.

@ScannerDanner 6 лет назад

I think I show it here ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-WKdZsWU2ZmI.html You do not need to SIA 2000 adapter, it is a P.O.S, just get a single test lead for COP ignition systems to use as your sync on a plug wire or ignition coil. I have the ones I use listed on the tools page of my website. www.scannerdanner.com/dmm-and-lab-scope-accessories.html

@kevinb2u2 5 лет назад

Found this video and your others when showing a customer links to info on jumped 3.6L chains. Paul, as a fellow Master Technician for over 25 years and about the same time since I joined iATN when they had 400 members - I can say that is just brilliant! I pride myself in knowing there is a test for everything, and have a nice collection of equipment and know how to use it. I do have a 2 channel Pico, along with an old Vantage, OTC Genisys scope, along a lot of other neat stuff. Have dealer level hardware and software for at least 7 manufacturers, and do programming on most also. I do not (yet) have a pressure transducer but after watching this video will be my next purchase. Also in having computer and electronics interests, I love your touch screen projection "board". What is that and how does it work? I can Google it to figure it out but wanted to compliment you on your experience and attitude. Kevin in Maine

@kevinb2u2 5 лет назад

I didn't know the "scope" of scannerdanner's reach when writing comment. Very popular for good reason.

@ScannerDanner 5 лет назад

Thanks Kevin! It's called a smartboard

@henkmoesker1313 8 лет назад

Had same 'fool you' experience on a 1 camshaft engine. Car seemed to run fine on higher RPM, terrible on idle. Monopoint so no injection issue, had 1 one plug wire which tested OL ohm when twisting so open. Cylinder drop test gave me spark but also 2 missing cylinders (!) from the 4. These were 2 and 3 on a firing order of 1, 2, 4, 3 so that explained reasonable running (lacking power of course) on higher RPM. These 2 cylinders ran on 1 of the 2 coils and you would easily be fooled into thinking the coil was the cause if you did not reason like a diagnostic guy should. Testing a bit further, relative compression test showed equal humps but did not feel right. Brought in the sync channel and only then noticed we had 2 cylinders and 2 with absolutely NO compression so it fooled me on first test (looking at scope image). Difference with your example; on a 4 cylinder, 1 cam car, a loss of compression on 2 cylinders is no timing issue. It is more likely valves, head gasket (not now, we had NO compression) or piston rings but that is another story. For this little 600 dollar car it was game over (too expensive to get this fixed) but there you go... how a first impression can fool you.

@ScannerDanner 8 лет назад

+Henk Moesker for sure! nice job Henk!

@chicanobluesaz4191 8 лет назад

GM dealer tech here. Gm doesnt rely too much if at all on scope diagnostics and yet when this video started and I saw the capture you initially showed, I asked myself immediately "why is there only 3 humps?"

@ScannerDanner 8 лет назад

+ChicanoBluesAZ nice catch bro

@chicanobluesaz4191 8 лет назад

+ScannerDanner I really like the way you teach. Your presentation is perfect and you make things extremely easy to understand. Just wanted to compliment you on that. And as far as you nor catching the missing 3 extra humps on the scope, believe me it happens to the best of us lol. In my career I have overlooked a lot of captain obvious stuff due to haste.

@henkmoesker1313 8 лет назад

+ChicanoBluesAZ Every tech that claims not to miss things that are obvious so once and a while, is either a liar or a real superman. Think we all have our share of 'why did I miss that' issues (a terrible journey through wires and digging out computers for a fuse issue is one I remember really well)...

@SEXYTECH1000 11 лет назад

YES YOUR RIGHT BUT THATS WHY I SAID FREE WHEELING , THE SPROCKET WILL STILL TURN, BUT THE CAM WON'T. BUT LIKE PAUL SAYS MANY VARIABLES ARE INVOLED,

@kaushikaithal 8 лет назад

Awesome !Simply fantastic..And by the way loved your book.I bought the e version of it.It would be nice to be if I could use it off line though.Thanks for sharing your knowledge .

@ScannerDanner 11 лет назад

That is correct my friend. a waste spark system would have looked very much like this and would have been good.

@DJDevon3 11 лет назад

That's true too. However, on my car that would knock out the crank sensor completely if the sprocket wasn't turning. Great point though as I imagine there are plenty of cars that don't operate that way which is why I watch ScannerDanner and others. :) Paul, in both instances you are using a labscope that most don't have access to, DIY'ers would have pull it apart. Great video for techs though nothing wrong with that.

@marcussho 6 лет назад

How many teeth can this engine jump before interference occurs?

@weldingjunkie 4 года назад

marcussho not all motors are interference they just won’t run or start

@bentonrodeheaver2596 4 года назад

Not positive but would say 4 would be the limit.

@Bartonovich52 3 года назад

This is an interference engine like virtually every engine made in the last 20 years.

@C8Kid 3 года назад

Is that a direct fuel injection engine? If it is I found this. Pressure Diagnostics You will never find a Schrader valve or port to measure pressure on a direct fuel injection system, even on the low side. If you were able to tap into the low side with an analog gauge, you would see pressures rapidly changing as demands on the engine changed. Direct injection pressure is measured with sensors, and the signals are used to determine pump speed and/or volume. So, you’ll need a scan tool to look at the pressures.

@nickayivor8432 2 года назад

Happy New year 🎉 ScannerDanner take care and have a great evening God bless you, your family around you ScannerDanner 🙏 🌟🌟🌟🌟🌟 Tutorial Great 🌟🌟🌟🌟 🌟 thank you very helpful video From Nick Ayivor from London England UK 🇬🇧

@stage3performance 11 лет назад

Seriously I can't say thank you enough. I'll be purchasing your Ebook soon

@ScannerDanner 11 лет назад

you have to cut me some slack man. this car was towed back to the garage that brought it to us. I have had no updates from them and truthfully I haven't asked for one. The main purpose of this video was to cover "relative compression testing variables" not "how to fix a no compression problem on three cylinders on the 3.6 engine". I realize you would like to know what exact mechanical part failed with the chain and so would I, I just don't have that info.

@bryangogan6050 6 лет назад

ScannerDanner agree 100%. Seen many of these engines. Total garbage. Best thing to do is remove intake hose and feel with your hand on throttle body while someone cranks engine. If not uniform suction during each cycle.. tell customer time for a new engine if you can find one. These engines are total garbage and way over engineered. Just looking for trouble. A 3.8 supercharged would put out close enough to the same powered and are tested and true. I am a tech and 41. They call these 3.6 l a high feature V6. I laugh and call it a high maintenance V6. Anyone else agree?

@sivucit 11 лет назад

Nice Video Paul.. Awesome explanation. Nothing related to this video, but on 6 cylinder engine, can I safely assume we will have 2 CAM sensor one for each bank minimum.. ?.. second, in this video, they have 2 CAM per bank , one for intake and other for exhaust, do u think that is for Variable valve timing monitors?.. pls advise

@theomnipresent1 8 лет назад

@9:25 it all clicked! I actually had noticed that there weren't enough humps between the ignition events. I couldn't figure how the cam and crank sensors would tell it to fire like it was a three cylinder? I assumed that there was an ignition timing issue and it was firing before rotating 720 degrees. Not seeing ANY sign of compression between the even peaks totally tricked me! After the epiphany I paused the video to think of ways to make sure I couldn't be had again! 1) If you knew the cranking rpm, and used your scope to measure the frequency/period of the waveform you could compare that to the actual engine rpm to confirm the ignition timing is correct & that compression humps are missing. 2) Another way would be if you used 3 channel's on a scope. Done the same way as you had in the beginning, but one more channel for the next cylinder in the firing order. An ignition signal would show up in the 'valley', revealing the hidden compression stroke! Maybe these would be viable tests, hopefully someone can let me know? Love the channel & content, keep up the good work!

@ScannerDanner 8 лет назад

+theomnipresent1 thanks so much!

@theomnipresent1 8 лет назад

Am I on the right track with those methods?

@JoelAutomotiveInaction 11 лет назад

I enjoy learning from you.

@delvonbullock8661 Год назад

Excellent video bro

@akafurtado7636 8 лет назад

I don't actually own a scope but recently ordered a new Pico and cant wait to get it and start using it. Love all your videos too!So just a thought .... Initially in this video you took the capture and just had the relative compression wave to work with . Without seeing the ignition event you assumed that the compression was good because of the way everything was uniform with the wave. Working with the initial capture if you had looked closely to the time that it took to get your 6 compression "humps" couldn't you have been able to see that the amount of time it took to get those "humps" was too long ? If the engine was healthy you would see the 6 humps in a smaller amount of time ? am I understanding this correctly ?Thanks again for the videos ! They are awesome .

@ScannerDanner 8 лет назад

+Aka Furtado yes, that is correct. I just didn't pay attention to the time base. I totally should have. Great question and insight my friend.

@akafurtado7636 8 лет назад

No problem ! Iam just glad that I was able to grasp the operation of the scope from watching the video. I have a feeling that after getting the picoscope I will never diagnose another car without it !

@ScannerDanner 11 лет назад

picoscope, snap-on Vantage Pro, snap-on Verus, and also look up something called a uScope from aeswave d o t c o m. This uScope is a single channel inexpensive scope that is great for people just starting out.

@theophilussmithiii7434 2 года назад

Good information. Why would the computer not throw a timing code?

@ScannerDanner 11 лет назад

yes, a waste spark system would have shown this type of pattern. (where you have a coil firing event every 360 of the crank)

@jimmymakwega3872 4 года назад

you are damn wright scanner danner, sync signal was the main player here, otherwise, you would never fix this car, as you said compression sound would throw you off, Thank you so much scannerdanner, parts changers will never ever fix this car ever ever....

@1964juls 8 лет назад

Dan, once again - thank you for another great video. I've seen these exhaust pressure transducers (firstlook brand). I am wondering if you've had any experience using rather than relative compression particularly on v6 and v8 for this example? I would have to think it would make more sense to use something to that effect considering how tough it is to reach the back bank of the engine. If you have, I think it would be great if you can share your experience with them.

@RayonsAutoDiagnostics 11 лет назад

that was technical but with experience its alot easier. thanks scannerdanner

@m.b.smoshitoa8325 4 года назад

Greedings Paul, for the correct timing you say the spark must happen exactly at the top of compression peak.whenever it is not you say timing is wrong. someone agued me saying spark must be few degrees before tdc. atleast 10 degree. so that fuel mixture have time to ignite and at tdc that is when it will be fully effective. i never heard you mentioning that anywhere. BLOM MOSHITOA (S AFRICA)

@ScannerDanner 4 года назад

Not sure I used the words "exactly at TDC". It is absolutely common to see timing anywhere from 10 degrees before to even after TDC. Had a Lexus that was at 7 degrees after TDC and it was normal during a cranking situation

@kevinc917 2 года назад

That bank is 2 4 6 but very good logic

@scientist100 3 года назад

So the valves were closing way off that there was no vacuum and a little compression in the intake at the wrong time. Unlikely to see so many jumped teeth but good to know for sure.

@karimjedda2154 11 лет назад

Hello Paul, I will receive my 4 channel standard kit + transducer kit soon,I'm really so interested by these techniques of diagnosing. Even if their prices are too expensive for a beginner I have decided to go ahead.

@leotech93 8 лет назад

Best lesson ever. Thank you bro.

@ScannerDanner 8 лет назад

thank you! I have hundreds more just like this

@PineHollowAutoDiagnostics 8 лет назад

Hi Paul, my friend Eric O. at South Main Auto just ran into this exact scenario on a 2005 Ford 4.0 V6...relative compression humps looked great, until I suggested to hook up a sync channel (this video really stuck in my mind!)...sure enough three humps were missing! My question is how can we have no compression or vacuum AT ALL inside the combustion chamber if the timing is off, but the camshaft is turning. I mean those valves should be closed and sealing at some point in time right? Unless all the valves are bent lol

@ScannerDanner 8 лет назад

+motoYam82 coul be bent, but it could be timing too. If either valve is open during the compression stroke, then obviously there would be no compression. They may be closed and sealing during the intake or exhaust strokes.

@PineHollowAutoDiagnostics 8 лет назад

Sure, but in general if the valves are sealing and the piston is moving (up or down, doesn't matter which stroke), there should be a significant change in pressure in the combustion chamber, right? Just wondering if we can use the in-cyl transducer to accurately see if we have bent valves inside...

@PineHollowAutoDiagnostics 8 лет назад

+motoYam82 At 19:00 the "dead" cylinder waveform can still tell us something. 1) We know that the cams are still turning, as shown by the two cam sensors. 2) The small pressure humps are less than 0.1psi peak-to-peak in amplitude. I would put money that the valves on that cylinder are NOT sealing the chamber at any point in time, i.e. they must be BENT and sticking open. 3) In 720deg of crank we see THREE distinct humps on the dead cyl waveform. Not sure which cyls are "backfeeding" pressure, but that again proves those valves are not sealing... So basically can we say to the customer: your cam timing is definitely off. However, there also appears to be valvetrain damage to the rear cyl head...much more expensive than just resetting the timing!! In that case tearing the valve cover off would almost be a waste of time...might be more economical to just swap the entire engine :)

@ScannerDanner 8 лет назад

+motoYam82 Not if the valves are closed during the downward movement of the piston and open during the upward movement. your cranking compression test will show basically nothing but your in cylinder transducer may reveal your issue. Not sure, I think there would be variables there too.

@PineHollowAutoDiagnostics 8 лет назад

+ScannerDanner Yeah I was thinking of the in-cylinder transducer which shows pressure and VACUUM (so valves sealing on a downward stroke would show up as vacuum). The traditional compression gauge and relative comp test wouldn't provide any additional info here... Will definitely keep an eye out for engines with timing issues to get some waveforms. Ever seen a Chevy 2.2L Ecotec with poorly sealing exhaust valves? Just got one in the shop here with a cyl3 misfire...reminds me of your Hummer misfire case study!

@oscar1105diaz 11 лет назад

I also noticed the same thing that technical lee said about the captures being mislabeled

@georgecareaga2846 11 лет назад

hey paul after watching the video one thing came to mind which was the variable valve timing actuator or solenoid for that bank 1 intake cam could possibly be the issue.what do you think?

@ScannerDanner 11 лет назад

cool man, where did you get it from?

@GRUSSNewton 11 лет назад

Very detailed video Paul but you make it easy to understand, please could you let us know the outcome?

@MassMechanic 10 лет назад

You say the Crank signal waveforms just looks that way, but you fail to notice the Amplitude and Frequency increase is directly related to the loss of compression on the 3 cylinders. In other words, the vehicle can be diagnosed with just the Crank waveform. This is one of those variables you are always talking about.

@ScannerDanner 10 лет назад

For sure, they do match, but that is also in hindsight don't you think? I have seen many irregular crank signals during cranking and it is completely normal. But I get what you are saying for sure, I should have caught that.

@prmayner 10 лет назад

I was thinking the same thing also. Good catch MassMechanic.

@prmayner 10 лет назад

ScannerDanner Great job Paul, just goes to show were all human and we can't think of everything all the time.

@ScannerDanner 11 лет назад

great info my friend. thank you for that! I definitely need to go back and watch that part again. it is possible i miss labeled that cyl head. so if it was a stuck cam phaser, would the repair still be a complete disassembly of the timing covers?

@sadboy8413 3 года назад

Hi I'm doing timing on a 11 chevy traverse and after taking everything off and was getting ready to set timing b4 taking chains of and noticed that it gets stuck wont turn a full turn any help would be appreciated.......p.s. b4 taking everything off i cranked it a few times with out any issues

@ScannerDanner 3 года назад

@@sadboy8413 why are you doing the chains? You may already have a bent valve? Post this to my forum www.scannerdanner.com/forum/post-your-repair-questions-here.html we can help you more there. It is free to join. Thanks!

@psicopatalucifer 11 лет назад

Thanks for another great video Paul.

@redclift30 11 лет назад

Stage3performance, I would buy the Hard copy of the book so you are able to highlight and do easy bookmarking!

@PaulCTownsend 3 года назад

Interesting as hell.

@DJDevon3 11 лет назад

I take it there are 2 separate timing chains on that vehicle? If no and there is only 1 chain and it's broken then how can you get 3 dead cylinders and 3 good cylinders with a good chain?

@PhillipBailey 8 лет назад

I was actually thinking about this COP system and I remembered that the Ford systems actually fire both coils of the companion cylinders until it receives the CID signal from the CMP sensor/s. I wonder how that would look. I'm going to have to do a relative compression test synced with a coil on one of those just to see. This car must have set cam correlation codes?

@ScannerDanner 11 лет назад

thank you Bri C!

@cobbysparks9891 4 года назад

You are just good like that. God Bless.

@redsson6669 11 лет назад

good stuff as usual, hey paul why did you skip all the fuel sections on your lectures? are you gonna go back to it eventually?

@theoldwizard998 11 лет назад

Just me, but I think I might have grabbed the crank pulse instead of one of the spark control line to begin with. I certainly would not have bothered looking a the cam signals, because they can vary a lot during cranking (cam phaser work off of oil pressure which is inconsistent during cranking). Perhaps (only perhaps) it may a been obvious during 720 degrees of crank rotation that there were only 3 starter current peaks (compression events).

@hddm3 11 лет назад

great vid, pauls the man again.

@ScannerDanner 11 лет назад

unfortunately most "old school mechanics" are parts changers. I am not saying they are all bad, but I most certainly would not want to learn from an older guy that says you do not need a scope in this field.

@BoltThrower321 11 лет назад

Damn ipad....this engine has also a variable camshaft and 4 cam sensors, my guess is, that those actuators are fine,but the camshafts are broken and in result of this, pistons are working fine but the cams are o. a wrong position and can't move due to the broken shaft, further I suppose that the timing chaiin has not jumped over....a common problem with gm engines are lenght/strechted chain/s. I advise you to remove the valve covers and than check your camshafts by cranking.

@dmorley100 11 лет назад

I'm gonna go out on a limb and say this shop did a timing chain job on this car before all this started being as these particular motors are bad about timing chains making noise and the only way to do chains on em is to pull the motor. Far as I'm concerned, if they did screw up a timing chain job I don't blame em cause these motors ain't easy to time right.

@mctobbsi 11 лет назад

Hi Paul! Once again a very nice video! If you would have been looking at a control signal for a regular coil firing two plugs at the same time the relationship between starter humps and timing would be ok? Is is not quite an easy mistake to do when working with different ignition systems?

@randhawaj1 11 лет назад

Great video Paul

@8953147 6 лет назад

Your the "Big Daddy" of troubleshooting for sure!! Funny ending!

@fsteddie98 6 лет назад

don't know if some one already said this but I believe the firing order on that eng is 1,2,3,4,5,6 and that is why you didn't think you had a compression issue at first. If the eng would of have a different firing order you would of heard it. does that make sense?

@ScannerDanner 6 лет назад

Regardless of firing order, one cam being off would have produced the same every other cylinder pattern on any V type engine.

@SEXYTECH1000 11 лет назад

PAUL, LOVE THIS VIDEO,,,,

@JustinMentionedIt 5 лет назад

The only thing that blew my mind is that touch screen projector, you have great videos , that tools awesome . I have codes P0016 17 18 and 19 ... any idea why? Throwing all those sensors codes does that mean something certain ?

@ScannerDanner 11 лет назад

agree and thank you jacob

@jhauna1 7 лет назад

Hey Paul good one again. I jus thinking if u had gotten a good waveform for this 3.6? It looks same as the Suzuki XL7 (2007-2008). Jus something to consider. 👍🏾

@ScannerDanner 11 лет назад

thanks Gary!

@alejandroamaro8303 8 лет назад

Hi Paul. im thinking about buying an oscilloscope, but is it necessary that i buy an amp clamp to use it for a relative compression test like you do? i can't just pierce a wire and measure current like that with the scope. i know i cant measure it like that with a multimeter unless i put it in series. but is it the same with a scope ? are the leads of an oscilliscope set to read current with one one lead like a clamp does? or do i have to put them in series as well ?

@ScannerDanner 8 лет назад

+Alejandro Amaro same as a multimeter bro.

@alejandroamaro8303 8 лет назад

+ScannerDanner okay. sorry for the dumb questions lol. I'm just a DYIer trying to learn more and more. plus, i can follow your videos better if i get one and take my Diagnostic skills to a whole new level. i really don't want to have a "swaptron" mentality just throwing new parts to cars thats why im trying to learn the right way by watching your videos. thanks for all your time btw bro

@ScannerDanner 8 лет назад

+Alejandro Amaro no apologies necessary my friend. It was a valid question. Just think of the scope as a really fast voltmeter

@alejandroamaro8303 8 лет назад

Okay. For Now... I was thinking about getting one with a 20Mhz Bandwith and 48 Ms/s sample rate.. Is that okay ? Or do i need a faster sample rate ?

@BoltThrower321 11 лет назад

@kevin I doubt it.....to tricky to get all those cilinders to tdc.@paul how about to check cam an crank signals, while you activate the variable camshaft actuators? Verus does the activation and pico shows you the signals...one way to check the timings. If the camshaft is really broken, you can test that with this method.

@robertmccully2792 9 лет назад

How does the computer know when there is bad compressions? It seems to me that almost all test can be shown from computer data lines, because of all the feedback to and from computer. Its all there, just have to know how to read am i correct? I am learning so i have not yet grasped my theory. But all the hookups your doing are already being done in some form or another. In fact it seems to me vacuum pressure hertz would narrow it down.. and so on....

@BoltThrower321 11 лет назад

Ok, let's evaluate the facts. Bank 1 has a good compressions (tested by current and transducer signals), bank 2 has not a compression.

@user-fy6rr6sz2n 5 месяцев назад

Thanks

@WillsHellaHeat 5 лет назад

have done a few 3.6l timing jobs on acadia and vue and treverse but doing a Saturn vue it jumped time guy took heads off had them redone but heads back on before i come into the picture i lined up all my marks like I always do no issues now that i got it all timed and goto rotate by hand i get about 1/2 rotation and it stops like its hitting something rotate backwards and stops in same spot number 6 cyl piston up and number 3 what could be the issue ? ive used my inspection camera and valves are open and pistons are up but do not appear to be hitting ive retimed it twice and same issue