VVT Tuning Noise - ADDED: Comparison Video
 

THE ISSUE:
I have heard this is multiple tunes, including the Perrin, Vish, and Visconti.
Vish explained it's simply a large change in VVT timing in a small amount of RPMs. (5 to 40 degrees)

I'd like more technical information on what exactly is creating the noise. Perrin said its resonance, Vish said its "rasp." Sounds like shit, and like valvetrain noise to me. With all of the tuning drama recently...

I'd like a straight answer as to mechanically what is happening, because if the long term effects of reducing torque dip has mechanical implications I want the VVT timing cut back.

SOUNDS OF THE MODIFIED VVT TUNING TO REDUCE TORQUE DIP
Here are the logs to accompany the video:

https://lh6.googleusercontent.com/-4...-h798-no/1.JPG

https://lh3.googleusercontent.com/-R...-h561-no/2.JPG

New comparison video, stock VVT map vs aggressive VVT tune:
[ame="http://www.youtube.com/watch?v=9t4QtTmfBsA"]Vortech FRS VVT Angle Comparison | P2 - YouTube[/ame]




Noise can be heard here Perrin Tune: at time -31.00 and -23.00

http://www.freesound.org/people/dezoris/sounds/191194/



And here on Vish dyno: At 22 Seconds

[ame="https://www.youtube.com/watch?v=Ptyi9mT0XoA"]OFT300 Development - YouTube[/ame]

At 22 Seconds


UPDATE: 3/11

Perrin modified my flash file to go back to a stockish VVT map from 2800-4200RPM range. After the flash the valve train noise is now gone.

The argument remains, tuners say the noise introduced from the optimal/aggressive VVT tuning is normal. Tuning VVT agressively can be done on FI or NA the same way, depends on the motor on how much noise it generates.

Given the unproven long term mechanical implications of those statements (if any) going back to a conservative VVT setting is good insurance for now.

There is no mechanical implication of running optimal VVT timing to minimize torque dip. If it's not something you want, just get a UEL header and run an appropriate UEL tune. Noise and dip gone.

I can second that first-hand. On the stage1 tune there was always rasp during that time. Since I've installed the header and moved to the stage2 tune.. there is no dip and no noise... but it is replaced with - oh sh!t this thing is moving!!!

The header is beautiful sounding in fact - can't help but run it through the gears every time to 5K or so... :D)

:burnrubber:

The VVT on this engine just changes the set angle of the camshaft itself. It doesn't create any extra lift and the duration of the valve opening remains the same therefore there is no extra stresses put on the valvetrain itself.


You have to remember that on the stock maps, the AVCS system is going through most of the range of the system anyway. What's the cause of the noise is the cam angle opening in relation to set events, perhaps extra overlap is causing it or earlier opening of the valve.

@shiv@vishnu
@Kodename47


So the extra overlap is causing a metallic sound in relation to set events such as what?

Shiv, a header, loss of O2 and a re-tune is not worth the cost to get rid of a metallic sound from cams due to the way the VVT is tuned.

I am not trying to be difficult but lets face it if you are capable of making changes to angles of VVT and other settings you should be able to completely explain why it is creating a mechanical sound.

Can you reduce the amount of angle change in tuning to eliminate the mechanical noise caused by trying to smooth out the tq dip?

I am looking for a more complete explanation of what really is happening to cause the metallic noise, not just hey, its ok.

Heard this from other tuners before, back it up.

I was wondering why at around 4krpm on a tuned stock exhaust car (mine), I was feeling and hearing shudder (is probably rasp) at WOT which would then disappear. Doesn't appear at partial throttle, or WOT in 6th, just 3rd of 4th. Probably b/c of the speed at which the revs are changing.

Have a look at this thread: http://www.ft86club.com/forums/showthread.php?t=57662

I've compared stock to the OFT tune. My guess is it's some form of resonance. Increasing overlap or changing the cam timing will have an effect on the way the air moves and in/out and around the cylinder.

Of course you could change the timing to get rid of the noise but you'd lose The power gained. I'm sure a compromise can be made though.

Answer: VTEC

This is by far the most detailed explanation I have seen thank you.
I would like to see how many degrees it needs to be reduced to eliminate the sound and the resulting power drop. I'd rather have a power drop than an unexplained metallic resonance.


It's not an air charge sound, or tone sounds like marbles getting ground up in valve train. It maybe old school but if it don't sound right then it probably isn't.

I don't agree with with the description of "metallic" noise. It's not metallic. People who describe it as such probably have never heard a real metallic engine noise before :)

It's just induction/valvetrain noise. You hear it in all NA engines to and extent. You hear it clear as day in VTEC honda motor just before the secondary cam kicks in. Personally, I don't even hear it unless I pay attention to it. However, I can hear a knock with the radio on, in the middle of a conversation. I guess I'm just more sensitive to things that unfriendly to engines.

Although I can't offer a technical answer or reason for it, I did note that the exact same noise is audible in the stock ROM just as torque comes back from the dip at ~4500rpm. The only difference is that it is quite brief in comparison to the tuned ROM's which change the cam timing significantly well before that RPM.

Let me throw this out here, I am not saying there is something wrong.
This motor and countless tunes are quiet during the overlap phase.
Why does pushing the angle change so far create "valvetrain" noise?
Because it is audible on the street, inside the cabin all the time.

If you back off the VVT angle the chatter goes away.

The angle change you are introducing is creating the noise, it's not something "typical."

I am not looking for a generic answer here.

You know what I know
You and I can't deny it

It does not sound right
Yes, same sounds

Some of my tunes cause more noise than others.

I don't know exactly what's going on here, but I can at least post about a few things that I've had some experience with. I'm not an NVH expert but I've had some exposure to it on a system design level and on an experimental/testing/optimization level. So I can suggest, for academic purposes at least, an experimental way to approach the issue.

So we know that exhaust makes noise, motor mounts and loose objects make noise, that kind of thing. The main things that are specific to a modern n/a DI engine are:

1) sound of the direct injection solenoid valves
2) sound of the high pressure fuel pump and fuel pulsation
3) sound of the hydraulic lash adjusters and valvetrain

There are a lot of things that affect engine NVH on a modern direct injected engine, but you can't figure out a root cause on a transient WOT from a chassis dyno like that. What you really need to do is put the engine into an NVH lab engine dyno. First thing I would do is motor the engine in 200rpm increments. Now what the hell does that mean?

Does this noise occur when the engine is actually firing, from a combustion event, or can you hear it when it's just spinning (like on a decel in the vehicle)? An electric motoring dyno bolts to the flywheel and spins the engine up and down to hold a speed. The engine doesn't have to run, but you can communicate with a prototype ECU in realtime and start commanding different AVCS positions. The beauty of that is that you can isolate whether the noise is coming from some valvetrain issue or fuel system issue without any combustion occurring. This is important because the pressure rise characteristics have a huge effect on engine NVH, especially on DI gas engines and diesels. Faster pressure rise=more noise, and that's one of the reasons why diesels are so loud.

So first I would motor the engine and see if I can audibly hear the sound, and see what my NVH instrumentation can pick up at the same time. Figure out the frequency and order of the noise in a motoring condition. Perform cam phasing sweeps at each steady-state rpm point and record data with different levels of intake and exhaust phasing. Generate plots of cam phasing vs various noise parameters (decibals, frequency, etc). Then repeat the test with the engine firing--actually run the engine at full load. See what the influence of combustion would be, and also perform cam phasing sweeps and fuel pressure sweeps to see what the influence of the high pressure fuel pump is.

Finally, I would feed that information to a simulation specialist who can do finite element analysis and figure out what the heck is making the noise. NVH simulations make little nifty animations that show the stress and strain on various engine components under different conditions, and can assess potential NVH. Then from all that work devise a countermeasure with hardware (motor mount, special engine cover, etc).

If a hardware countermeasure is not possible, look at your cam phasing sweeps, look at your NVH data, and determine what is an unacceptable level of NVH. Figure out which set of engine parameters fall create the unacceptable level of NVH. Weigh that versus engine performance and combustion data, and make a judgment to create a calibration-based NVH countermeasure in lieu of a hardware change.

Uh.
ITS VVT

The overlap at cold start on the factory tune is definitely not quiet.

Maybe you could post a datalog from your car (which doesn't make this noise, correct?) showing your vvt angles and we can compare with one that does.

- AdrianG

Your issue is placing visconti in the same light as the other 2 thinking there must be something wrong.
I am nearly 100% certain visconti did not play with the cam phasing until shiv posted it up so what you heard with visconti is not the same with the other two.

My car has valvetrain noise during overlap on perrin tune. Even more pronounced than Shivs.
This has nothing to do with cold starts. Its about the sound in the videos at specified times at normal operating temps.

What exactly are you claiming is "valvetrain noise"? Are you suggesting the timing chain is making noise, or the valves themselves are making noises? Just because a noise is appearing from a different cam angle doesn't mean it's a noise being made in the valvetrain. Adding overlap can increase intake noise quite a bit, maybe that's what you're hearing?

I've listened to the sound clips a few times and don't hear anything remotely alarming, so either you're being paranoid, or the clips really don't represent the noise well at all.

Runinng Shiv's tunes I can hear a change in the engine noise right around 3800 rpm or so. With e85, the noise is even louder. Comparing the exhaust valve advance on the logs with what I hear, they certainly lineup. The sound has all of the characteristic rasp of an exhaust that has imbalanced pulses.

Could it have something to do with the direct injection? My tuner mentioned something about the DI making some serious noise when figuring out how to tune my car.

interesting. Always wondered what that noise was.

:popcorn:

I went out for a drive tonight with the windows down to listen for any new noises after flashing with an OFT. There's definitely a noise in the ~3200-4200rpm range, but it definitely doesn't sound mechanical in the valvetrain to me at all. It definitely sounds like rasp, and is more audible at part throttle than at WOT.

It's like intake rasp in terms of what it sounds like. It's not noticeable at low speeds, but it is at freeway speeds. That's why I think it's an intake noise.

Either way, if it's normal, then that's cool.

On phone I am. Therefore, if mistakes I make, Frank Oz blame you should.

OP needs to a bit more direct in accusing Shiv of being a BS artist.

I know what you are talking about.. In both my tunes from fa20club and now e85 from Bill. Its like were the torque dip is in that range of the rpm's, on mine it sounds like my header or OP is rattling to shit. But i checked everything and found nothing, flashed to stock and noise is gone.

Sounds like an exhaust leak almost around 3500-4000RPM right? Like a metallic rattle..... Stock tune doesn't do it, its gotta be the exhaust note due to aggressive cam phasing. Could be why there is a torque dip in the first place, people would complain of the engine note and think something is wrong.

Just my theory of course

basicly what I think it is also

see here:

http://www.ft86club.com/forums/showthread.php?t=47263

also you can hear it in this video

[ame="https://www.youtube.com/watch?v=bw_f3ZS78vk#t=36"]SCION FR-S OPENFLASH Header - YouTube[/ame]

I wouldn't say shiv is a BS artist. His stuff does as advertised & he's a good tuner. It's just not the be-all end-all solution it's marketed to be. On par with other unlocked tuning solutions but easier? Sure.

He's a good marketer is all. Not a bs artist.

On phone I am. Therefore, if mistakes I make, Frank Oz blame you should.

I here it exactly 4-5k and my car is stock. I've read removing the sound tube gets rid off it. I'm used to it by now.Also real 0w20 oil reduces the noise.

I first noticed the noise when MPT was dialing in the engine on AEM series 2 (sans DI) the noise is almost assuredly the cam phazers themselves, they work using the ratcheting effect of the valve spring resistance against the cam rotation, decreasing the rate of change in cam angle decreases the noise drastically.

If you pay alot of attention you can hear this even on a stock tune, it is just not as prominent because the rate of change is much less, there is probably some amount of delta the factory allowed between rpm or load breakpoints.

If you ask the cams to go from full retard to full advance (or visca versa) in one break point it goes crazy for a couple hundred RPM trying to get your desired angle.

Other systems make less noise because they require the oil pump to move the cams, or rely on different technology entirely. there are benefits to this type of phazer, this is the drawback.

I have my sound tube, and while I removed it before I got tuned, I suspect that the noise would've been greater than it is now. But, it's still there even without the tube (and the cabin hole is plugged by a sealed gromet through which my 5ch amp's power line is run through). However, I hasten to reemphasize that the sound is not annoying. It's just noticable as the sound changes from normal "hrmmmm" sound of the engine intake + exhaust at street and cruising revs, to more of a "brrrrrwahhhhh!" as it moves between 3200 and 4k, then keeps that sound, but quiets down above 4k (in terms of intake noise), while exhaust volume increases with the revs.

It doesn't sound sick or bad or anything, just different.

Could this damage or cause significant pre-mature wear and tear in the long run?

Well I am not calling out anyone. I asked, Shiv and Perrin, neither can answer the mechanical cause for the noise.

What this means to me is they are are focused on the the cause and effects of changing the cam angles on the dyno. The fact that they don't have an answer as to why the changes they made introduces "valvetrain" noise immediately rules out continuing to run the tune in the current state regardless of if it makes more power or not.

More than likely people are describing different noises that are all timed around the heavy advance of the intake cam. The intake cam phasing and the direct injection pump phasing go hand and hand. Tuning the cam aggressively can gain some power down there and it does make intake resonances but on some cars you can get the "marbles" or almost "knocking" sounds. When I had to work out the DI pump targets, duty cycles, phasing, dump valve, etc with the Hydra EMS I could induce significant DI pump noise. Careful tuning and asking only what the pump could deliver is critical!

Now the reason some get this "marble" sound and other's don't could be tied into how well the DI pump is working. Pulling back on intake cam advance can silence this sound but its just a sign the car may have a faulty DI pump.

Two different sounds, one normal, and one is bad!

Thanks,
Phil Grabow

I have heard what you describe since re tuning my car on the new header. Sounds like an exhaust leak to me but checked everything mechanical wise and nothing.

http://www.thisoldbrain.net/wp-conte...010/10/FUD.jpg

http://techmarketingscoop.com/wp-con.../07/No_FUD.jpg

So basically you're accusing them of causing an issue with no proof other than you don't like the noise? Have you not read the posts from people stating they get the noise on the stock tune if you listen carefully?

I'd read the quoted post below, flash back to stock, fill up with crappy e10 or e15 gas and go to the dealership complaining about the cricket noise to see if they'll do the DI pump TSB for you. Then see if you still have the same noise, or if it's a different one. Mine definitely doesn't sound like marbles or anything harsh, just a raspy resonance in the intake. The videos you posted don't sound like marbles or knocking either?

That's some good info. I get some noise on mine, but it's not a harsh marble sounding noise, just a minor rasp.

Mine has also always made a different noise (almost sounds like a tractor) at very low RPM's, but it's very brief and every other manual car I've driven makes the same noise.