How Variable Valve Timing Works
ฝัง
- เผยแพร่เมื่อ 29 มิ.ย. 2024
- Here's how the Variable Valve Timing System Works on a car's engine.
The four-stroke internal combustion engine consists of gasoline-rich air entering the cylinder in the intake stroke, compressed, then ignited to push the piston down to rotate the crankshaft in the power stroke. The piston then returns to the top pushing the exhaust gases out the valves, only for the cycle to be repeated over again.
Variable valve timing optimizes fuel economy, thermal efficiency and emissions. An oil activated cam-phaser actuator is controlled by the ECU through an oil control valve. Oil pressure is sent through the VVT gear to fill up cavities to advance or retard timing. A closed loop control system utilizing the cam and crank position sensors is formed to ensure optimal timing by the ECU for either more power, or less emissions.
In this video, the engine from an Infiniti G35 (VQ35DE) is taken apart to explain the components of the variable valve timing system, including the oil control valve, camshaft bearing caps, timing tensioner, engine head, valves, camshaft and pistons.
Make sure you change your engine oil frequently!
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Reference videos:
How an Engine Works (3.5L V6 Nissan VQ35DE):
• How an Engine Works
How the Engine Lubrication System Works (3.5L V6 Nissan VQ35DE):
• Why ENGINE OIL is so I...
How to remove an engine:
• How to Remove a Car En...
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Make sure you change your engine oil frequently!
Here's where to get OEM oil filters:
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Engine oil:
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Dude, I love you, literally. Such a detailed explanation.
Awesome! Glad you learned something about VVT
I'm an electrical engineer after a veering away from mechanical engineering freshman year of college. It constantly amazes me how mech engineers develop very intricate control loops with machined aluminum parts that mimic control loops on my circuit boards. The VVT system described in this video is a mechanical work of art, especially the phaser.
A while back I replaced the VVT control valve on my Prius and wondered how an simple external part wears out sooner than the intricate spinning cam phaser. I think the reason is that the control valve's electromagnet is feeble and has no spare thrust to overcome carbon deposits. A cam phaser has 80 psi of oil pressure behind it to accomplish its job.
Like other posters to this forum, I agree that the video underscores the importance of clean engine oil.
Good feedback. I'm a mechanical engineer and my brother is an electrical engineer. It's so interesting to see how these have to work together
Another masterpiece, sir. I've had my 16 year old son watch several of your vids because the visuals are so helpful. I can explain this stuff til I'm blue in the face but to see the parts as they're torn down cant be beat.
I'm glad I can help you guys out!
I just watched a two part video explanation of this with a scanner and was completely lost. Thank you for SHOWING how it works. Very simple now.
Glad you learned something
I like how he said "I'm just gonna come in with my xxx shirt etc." Really detailed in everything xD
Gotta have the right tools for the job
@@speedkar99 Alright man, keep up the good work😎
Very nicely done, Sir! I watched some other videos on how VVT works, and yours is *by far* the best at explaining how the system works. I've often wondered how this feature on some engines functions, and today just decided to answer my question with a query to TH-cam. Sadly, your presentation came up a bit down the list. I wish I would have seen it first. You manage to explain how this somewhat complicated system works in a very clear, concise, and understandable format. Thank you for the effort you put in to make this very educational video.
What a fantastic presentation of VVT working. Thank you very much all the way from Maputo/Mozambique. We have a lot of Cars here with 1MZ-FE engines
TH-cam teaches more than any college can teach. Thanks for the wonderful video.
absolutely. colleges should do away with classes and only do final tests... Teach yourself and pay for the formal accreditation!
ease of explanation tells the depth of knowledge that you have. very educative. Thank you. Regards
Nicely detailed! Thanks for your effort, keep up, great stuff.
No problem. Glad you learned something
Oh, cool, I wanted to know that, since I've read a lot about why the VVT gear knocks some time(when starting the car), but this really helped me understand the inner workings :)
Yea it's exactly that little spring stopper wearing out. My Camry does that on cold starts.
This man knows what he's talking about a great mechanic, if its anybody I want help to fix my car it's him
Thanks. I don't fix cars, I take them apart ☺️. I'm not a mechanic, I'm an engineer.
Well I wish I knew you personally
finally I understood the mechanism or at least I have an idea, it is a little complicated , but thanks to the opening of the components I learnt the lesson, Thank you so much for the explanation, You earned a like an a new subscriber
Glad you learned something new
Incredible explanation. Thank you.
Request: "How manual transmissions work"
Thanks, it's been suggested many times.
If I can get my hands on a manual car I sure will tear down the transmission
speedkar99 preferably FWD ones. Because it doesn’t seem to be as simple as RWD cars
@@speedkar99 Yeah, when someone comes for oil change, tear that transmission down. It will be very helpful.
wow...i had no idea what VVT was. Thank you so much for posting this video. Very complex indeed. Wow!
Good stuff bro. Easy to understand and also enjoyable to watch.
Glad you enjoyed watching it!
I will love to see how a CVT transmission works. Hope to see a video explaining it soon. Love your videos btw!
Thanks
I'd love to get my hands in a CVT!
That engine block is immaculate... 👍
Funny how the cam shaft and gears are not 😁
Talk about dont judge an engine by its outside 😎
Hey... follow my Instagram I'll have stories up on why it's so shiny and what I'm doing with the engine 😉
Great explanation...👍
Hey man..! Great explanation... Here from Colombia just researching some stuff of the Downzising and the superknock too..(you know, bad gasoil quality) great way to do the class. Thank you and greetings from Medellín.
Glad you found my video useful
Great videos sir I love that I can understand my VQ37VHR that much more. Really is a great engine when it comes down to design
Yep very sturdy. Check out my Nissan VQ engine video for more.
@@speedkar99 I know they are. At 236k on mine. Sitting here with all the timing components and galley gasket replacement parts so that I can get at least 100,000 more.
Thanx mate, well done fir such an awesome tutorial. Love from Australia
wonderful description. thanks a lot. it was so helpful.
Great stuff man! Love to see a new camry mechanical video.
Sure thing. I don't want to overdo the Toyotas though haha
Exceptionally well done!
Thanks
I need this toothbrush and this sock, the secret of your knowledge. Great job mate.
Brilliant explanation!
Awesome thanks
You are helping me learn so much.thank you
You are welcome
What a great video.
Bravo!
Thank you very much!
Very good explanation, thank you.
Welcome
WoW.. what was that..👏👏👏👏👏
Really can't tell how great this video is
Awesome
Glad you enjoyed it
Great video!
Excellent video.
👍
WHO KNEW! Thanks forthe break down. Seems complicated. Makes me want to go do an oil change.
Yes please keep your engine full of clean oil!
Dude u saved my car with this video had a p0021 code couldn't figure it out vvt sprocket where the plunger is was broken internally
Very informative, thank you.
Excellent bro
Excellent video for learning about vvti bro👌👌👏👏👏👏
Technically this isn't VVT-I, it's just Nissans VVT. vvti is for Toyotas only
What a great review. It seems this system as shown does not allow a change in the duration of valve opening, which is dependent on the shape of the cam lobe. So, when you open a valve early it must close early. I was a little confused when you said that pumping losses are reduced both when you close the intake early and when you close the intake late. Presumably this depends on intake pressure, turbo effects, etc. It would be interesting to see a practical summary of how the PCM behaves in different situations, WOT, cold start, coasting on the highway, etc. There is enough detail there for a whole extra video....
Toyota has developed VVT-iw with the w standing for wide, allowing for more angle.
The ECU would sure be an interesting study, if only the coding and logic was as easy to decipher as mechanical systems like this!
Smartest mechanic
I'm not a mechanic
I'm an engineer
Watching your video has given me a thought on solving a problem with my 2007 X-Trail when cold. Lack of power until its really warm and even then it lacks grunt. You touched on wear inside the oil mechanism that controls the valve timing and a slight you get when starting the engine up..
I'm gonna post a video on exactly that next week. The famous VVti rattle!
Take out the vvt solenoid and filter and clean it thoroughly, just did that on my kia and it feels like i just unlocked 10hp extra, car is very eager to move on low revs unlike before when it would always want to stall.
Also, don't forget to use the recomended engine oil for your engine, nothing thicker, vvt systems are very sensitive to types of oil.
That was fascinating.
Awesome thanks
Awesome video once again speedkar99! Very interesting stuff.i wonder how beneficial this is in the overall life of an engine in terms of mpg improvements and emissions. Some fairly complicated mechanical additions to make it all happen.luckily I have never had to replace my solenoids or actuators but I keep my oil well maintained. Thanks again.
Its to meet government standards
The peaces that you show in 3:30 are also there to seal the chambers and prevent oil to leak from one chamber to another :)
Yes it's a sealant too!
reminds me of a rotary engine
Mantap mang
Great video Thank you! How likely is the possibility of a cam sprocket breaking ?
I did not realize that vvt was so simple. Thank you for that! If we could just use solenoids to control the valves directly and be able to control not just the timing but the duration.....ah. Never change a cam again - ditch the cam altogether! This is already being worked on, it seems.
Soon we will have the free-valve...all controlled electronically with each valve having a solenoid
The Koenigsegg gemera has a 3-cylinder camless engine that puts out something like 600hp!
@@speedkar99That's not good. Good in theory I guess but prone to failure and costly. My 2015 Hyundai sonata is currently using ecvvt meaning the intake valve is controlled electronically via motorized cam phaser mounted on the camshaft to allow the ECU to advance or re t a rd. Well guess what? Those phasers are known to fail, noted in so many customers complaints. And unlike the regular intake valve solenoid that could easily be replaced in 5 minutes with a $30 part, the electronic intake valve timing is a pain in the butt to replace and a $2000, $3000 $4000 dollar job since the timing case would have to be taken apart to get to the cam phaser.
That's what you call an explanation 👍✌️
Thanks
You are so amazing how you get all these information on vvT in simple why
I learn By taking things apart
Awesome video again. Plz do a video on manual transmission working 🙏😑. I will remember to use socks to wipe oily parts. 👍
I need a transmission to tear down...
If I can get my hands on it then I will. Thanks
Good video buddy.
Thanks. Haven't seen you in a while
@@speedkar99 Always here. Didn't miss a single video.
you should do a video on the Nissan magnetic variable valve timing works, newer VQ's use it on the exhaust side..
Thank you sir
You are welcome
well this is something I already had some idea so understood very well.
and a bling bling block.
Shiny VQ35 eh
He always kills me with the "my brothers old socks", "old toothbrush", etc.
The wear bar and spring arrangement looks like apex seals on a rotary.
They sure do
Sick!!
😏
... And then when you realise that with the advent of electric vehicles all these gems of human ingenuity will fade in oblivion, nothing gets more depressing. That we humans managed to get all that minute oil flows in those 'mechanical circuits' so reliably at such a high frequency - is an achievement enough for the human race. My salute to all the people who imagined it and built it over so many years. My Jaws remain dropped everytime I get to understand such mechanicals.
I agree. The lubrication system is a marvel
I agree entirely, Shreyas! It's incredible that mechanical engineers create powerful yet intricate servos inside spinning gears, controlled by the oil that lubricates them. Makes the electronic parts on my circuit boards at work seem like a walk in the park.
Your automotive channel has some of the best videos on TH-cam.
First off, the camshafts in this video are hideous. Please tell me they were pulled from the bone yard.
It seems to me the cam phasers are either "off" or "on" triggered by the ECU. The duration of the lift does not change, it is only when the valves start to open relative to the pistons. Is this correct?
Thanks. The cams sat outside a while when I disassembled the engine.
VVt is a closed loop continuous control system with the cam sensor, not just on off.
Awsome!
Thanks
I smell another V6 engine coffee table coming up...
Haha this one is already done
Enjoy your video immensely. By the way, has your brother ever complained about missing socks that later turned up oily? What was your response?
Natural selection applies to socks. His stock pile could use repleshing anyway
The toothbrush really brought it all together for me.
It sure is a good contributer
🤣🤣🤣
Nice 1
Thanks
Thank you for very informative video. I watched this because my 2015 Hyundai Elantra failed to start last week I have reasonable wrenching skills and I can explain that the starting sequence sounded like the starter motor Bendix did not engage the flywheel . Then I looked under the hood as somebody else crank the vehicle and saw that the serpentine belt and the crank and alternator were all spinning beautifully but it sounded there was no compression gallop. Upon much more cranking pretty soon you could hear the engine starting to gallop with compression and it started immediately. The only thing I can think of is something to do with the VVT? It was spinning like it didn't have a cam chain or didn't have any valves. Then after five or six minutes of spinning suddenly you could hear compression build and at that second the engine started. My mechanic is buffaloed and doesn't know what to do
I have a 2015 sonata that does the same thing. The cam shaft phaser is most likely at fault and needs to be replaced. Do you ever get it fixed? If so what did you do?
Hello, I have done no repairs and the problem never resurfaced and it has been at least 8 months and over 10,000 km of no issues. When I had the problem on my Elantra I had done my oil change and filter change. I then back to the car up into the garage then the next day I had to back the car out of the garage and shut it off. Then I went to start at the next day and I got that strange no compression. My working theory is this, that I did the oil change and as usual I did not fill up my oil filter with fresh oil when reinstalling . My working theory is that a small air bubble got in the oil pressure line as normally would happen but my two short 30-second runs of the engine might have allowed the air bubble to be right in the cam phasers when I shut it down I have since done an oil change and this time I ran it up and down the road for 15 minutes. It has been running fine all I can think is that it had something to do with that oil change as I had done to 30 second engine runs in 2 days. Possible airlock air bubble in the oil pressure operated phasers
Just wondering, did your issue happen after an oil change
Excellent video! I am actually having trouble with my oil solenoid valve at the moment, it is making the rattle you described on start up! Now I know what to look at, thanks . Is vvt the same as vtech?
The OCV what controls the VVT gear. The rattle comes from that pin inside the VVT gear. VTEC is different...that controls how much the valve lifts up
be sure to use proper oil viscosity w30 or w40... the modern w20 oil is super thin and hardly a lubricant specially for V6 or V8 engine camshafts, the rear journals on the passenger side suffer from low pressure because of wear tolerance create leaks
👍
Awesome
Thanks
@@speedkar99 sir plz reply on insta
My man, very well done and presented thank you!!
And to that one thumbs down, get a life man!!
You are welcome!
This guy is the Albert Einstein of engines.
How are the engine block and head so clean??
Very interesting. I own a Focus MK 2 with the 115 HP 1.6L Ti-VCT engine. The engine has a rather poor reputation being often cited to be a "hybrid" between the regular 1.8L 125 HP engine and the 100 HP 1.6L 100 HP engine.... as in having the performance of the 1.6L 100 HP engine but the fuel consumption of the 1.8L. It certainly feels too thirsty for its felt power output. There is also the issue of reliability and justification for such a complex technology in an engine that by all means and accounts is little more than a crappy 1.6L standard naturally aspirated engine. What I mean to say is.... you can have basically the same power output and fuel consumption with a regular 1.6L engine.... except those dont have 4 rather expensive variable cam timers that add another point of failure. Yes, it doesnt have an EGR valve because it does this via cam timing... but then EGR isnt such a common failure on gasoline engines but more on diesels - at least to my knowledge.
Overall, there imho just isnt enough justification in terms of performance and fuel consumption gains compared to increased repair risk and cost. Not to mention the need to be more conscientious about oil changes with it which is another nail into the cost benefits of it. Most gasoline cars in europe are primarly used as short to mid range city vehicles as regular long range drivers lean towards diesels. I mean before VW decided to cheat.
So you have a car with high fuel consumption and low power.... it at least should be cheap in maintenance and survive rough treatment because in terms of economics... it simple isnt worth gentle maintenance, it only has to live long enough to outlast the rust.
There is an filter mesh before the VCT units oil supply that is meant to protect the VCT unit from debris in the oil - a good idea in principle but the original mesh/oil supply diameter was pretty small and as such if you are unlucky, it gets clogged completly and starves the VCT unit in question of oil with predictable results. Later models have increased the oil pipes diameter and also switched to a better oil, for the most part increasing reliability to acceptable levels. Still a lot of technology for very little direct visible driver/owner gain.
On the bright side, on more modern turbocharged direct injected engines like the Ecoboost - it probably can achieve higher gains and also due to higher overall performance and actually visible fuel consumption gains, can there also justify increased maintenance costs. The 1.0 L 3 Cylinder ecoboost is quite a fascinating engine, using a watercooled exhaust manifold to reduce or even avoid the need to enrich the fuel mixture to protect the turbo/catalytic converter from high sustained engine loads exhaust temperatures.
Would be helpfull I think, if all the diagrams you show on your videos, could be downloaded somehow, so we can read them over and over when we need them ;)
I get them from the repair manuals
great content! quick question.. on a g35 v6 the 4 bolts on the cam actuator do they come loose? if so would it be a good ideal to remove the cover and inspect to tighten? what would there torque setting be? making start up noise.
thanks
Did u ever do it I’m having same issues and I just got new timing chain I got code poo11bank 1 before Timimg chain fix it was bank 2
Very good explanation Mr.Brush 😉 I'm only interesting at what speed vvti is engaged?🤔
That's all computer controlled.
Hi. There are some videos out there regarding the Honda K24 and K20 engines, where they open up the front cover of the VTC actuator and than just take out the actual lock pin spring and stretch it and then they place it back in. Many claim that no more rattle after. What do you think about that? Thanks
Nice :))
Did air pressure test on a VVT cam phaser. The air pressure was leaking out from the rear of the cam phaser. Im pretty sure this is no pressure relief system.
I guess the engine is a complex mechanical device:)👍
It definitely is! Very complex but the ecu is even more complex
Question. So is it only the intake cams that are controlled by the system? Or are the exhaust and intake controlled together; and dont adjust relative to each other? Or did I miss something. If so, are there engines with independent vvt for all cams? I just got my first vvt engine.
Will that rattle noise when it starts up cold will it harm the engine it goes about 2 seconds and then you won't hear it anymore is it necessary to change the actuator
See my engine rattle video
There is nothing i take very serious than not skipping my oil changes
Reminded me of apex seals on a rotary.
Seems like a very limited range of motion.
Agreed on both there!
Nice video! Was a Toyota engine?
Variable valve timing on a small-block Chevy is when the chain lets go; variable valve timing and lift is when your camshaft bearings are toast.
Ouch. Those are tough
If solenoid not being elektrick ....is the piston position blok the oil line or not...
Or it in posisiton netral...just rublication of chamsaft only not make a hidraulik fuction?
Hi Dear,
My Peugeot recorded "camshaft dephaser" on OBD and the engine has very loud sound and low acceleration, do you think this means I've to replace just the vvt solenoid first or it's better to replace both the solenoid and the camshaft dephaser gear?
How do we know if there's a problem/ sign of failure in four engine cylinder valve timing?
As always, a great video but the brush looks very bad. If you buy your brother an electric toothbrush you may clean all that parts much quicker.
Good thought.
Heeey baby, there you are :)
This is so simple and less complicated than the ones on a Tesla!
VVT in Tesla?
can you pleae make vido about relay and fuse box
I have 2 wiring harnesses waiting for me to dig into...that video is on my list!
@@speedkar99 thanks
Speedkar99 Just a quick question, I sometimes get this rattle you've mentioned, and as you said, the reason could be that pin that is worn out. Now, I've found that if I turn the key on, wait 5 seconds, and then start the car, it does not rattle. But if I turn the key on, and I immediately start the car, it does rattle. Do you know what could be the reason behind that? Thanks again for your videos!
Hmm I'm not sure because the oil pump is mechanical, so it's not like it builds up oil pressure before you start the engine. My Camry does the rattle on cold starts as well I should try that.
Does this really work?
@@speedkar99 Did it work?
OK, so what are the odds of this being the one second rattle on a cold start up what most people think is the timing chain tensioner going bad or a stretched out timing chain, my timing reads a steady 15° at idle warmed up, so I’m assuming my timing chain is not stretched, that one second rattle, if I let the car sit for a couple hours after running, the tensioner holds pressure for a good couple hours before it will have that rattle again, then disappears immediately, and engine is quiet, as can be 160k miles, burns no oil in between 3000 mile OCI’s
2006 VQ35DE eng. (G35 coupe)
Also, the cover on the timing chain cover right in front of assuming that actuator is that a service hole for that issue cannot be fixed without pulling the timing cover?
The VT device, is that what pulls timing is when knock is sensed?
That is another sensor, usually screwed on to the engine block. It looks like coolant temp sensor, but Its is a piezo electric crystal that generates a voltage pulse - during knock - that the ECU will see and the ecu will pull ignition timing immediately until the event resolved. It works like the triggers on a outdoor gas grill that make a spark when you push the red button and it lights the grill. HTH - Sandy
I think it's time to grab another one of your brothers toothbrush, that toothbrush in the 4 stroke demonstration is just screaming for retirement....😄😄🤣😂
It was his wife's tooth brush!!!!! OMG 😂🤣😂🤣 wrote my las comment during play.....I love it.....
Agreed!
Natural selection applied for toothbrushes too 😏
Do you know if the VTC sprocket spring/pin is rebuildable? My VQ35DE makes a rattle on cold starts and I would rather open it and replace this spring instead of paying for the whole sprocket that is $400+
How about a used one? I'm not sure where you'd get parts to rebuild that
@@speedkar99 Ehh yes they have used ones.. But I feel like with a used one I might come across the same problem. Will it hurt anything keeping it like this?
nice video
please which country are u coming from
Canada
Pls can u direct me to any mechatronics institute there ?
Haven't you already made a similar video on the same topic ?
Yes. That was Toyota's VVT-i system which is very similar in operation.