Tip In Knock?!
 

I've read around about the issues of the 'Throttle tip in knock' sound that some of our cars get, but had no fix/solution to stop it from happening again.
No engine/power mods on the car, and before when it was completely stock I still had the same issue? Just wondering if there's anyone that had this issue and got it resolved. Thought my Oil Change would change it, it did for a bit then it came back.

Happens when I'm coasting then I start re-applying some throttle and it'll come and happen for a few seconds then it stops.

Went twice to double check if it was my heat shield and it isn't, so this is almost what I come to the conclusion of.

For those who need a auditory understanding, here is something almost identical to mine.
[ame="https://www.youtube.com/watch?v=g8nnFeP7ib0"]Frs/Subaru Brz "tip in knock"? and VVT sound - YouTube[/ame]

Hmm that doent sound like tip in knock. But you rearly need to log ecu parameteds to be sure. Detonation pre Ignition or pinging or igniion knock is usally a more high pitched tinny sound like ball bearings in a tin can.

The noise in that video sound like a mechanical noise like vvt rasp or resonance or engine bearings on the way out or low oil levels\pressure or something rattling

Tip In Knock?!
 

I think he is referring to the click on shifts when the throttle is reapplied. My car does this too. This video isn’t a good example. I’ve seen others post videos of this problem that sound better. On my car it without a doubt sounds like knock. I’ve been at the car thing for a long time and recognize knock.

Listen to the video again but focus more on the sound between gears and see what you think.

Maybe I will get a recording of my car today.

There is also a thread that I think Tor started which was about tip in knock where you pointed out that the transient ignition retard table for the 2017 roms changed. If I recall Tor took this new table and dropped it on his tune and the tip in knock sounds went away.

I have this click too and it drives me mental. Doesn't happen every single time I shift, but when it does, it bothers me to no end.

video is definitely the throttle body noise, not knock

I would think if it was the TB that you would hear it on every shift which you don’t. It only happens when you rush back to the throttle on a shift. I am not even talking about WOT. I’m talking about light throttle but just rushed. As long as you delay your throttle application then It will not make the pinging sound. I’ve also tried to duplicate this sound with the engine off and the TB does not make the same pinging sound that I hear on quick shifts in my car. Yes I hear the TB but it isn’t the same sound.

Isn't this the same sound posted few years ago of those that had issues with the seals going on the injectors? I can't find the video of the sound but here is a link to a long discussion of the issue (the sound may be buried in the tread)

http://www.ft86club.com/forums/showt...injector+seals

The seals make a popping sound kind of like a cork gun rather than a clicking/pinging sound.

I can reproduce tip-in knock at will in the same way that OP describes. I don't know much about what the ECU is doing except that it's waking up from fuel cut.

1. Drive for a good long period a steady highway speed.

2. Lift completely for long enough to go into fuel cut.

3. Stab at it. Doesn't take much.

Like @ermax describes, it can be avoided by applying throttle in two stages. First crack it open to wake up the injectors. Then go ham-fisted (footed?) with confidence.

I think a data log of the throttle position in sync with an audio recording may be handy. Do some shifts where you avoid the pinging sound and some shifts where you invoke the pinging and then you should see how the throttle is applied. You should be able to see that it isn’t rapid movement of the TB that makes the sound. It seems to be all about how quickly you get back on the throttle between shifts. Sure it’s easy to avoid but I have to drive the car unlike any other car I’ve ever driven. Who wants a sports car that you can’t do quick crisp shits without being haunted by a sound that resembles detonation so much you cringe every time.

As I said before, Tor has this sound (even linked to this same video) and he was able to resolve it with the 2017 transient restart table. It it really was just DBW making sounds then why would changes to the transient retard table have any impact on the sound?

Exactly my situation, even in neutral and I throttle it, you'll hear a minor resemblance of the sound on the initial 'stab' at the throttle and then it goes away.

If you stab at idle you will also hear the intake gulp up air. If this is what you are referring to this is something else. Almost all cars do this but the 86 seems to do it more than others. It’s almost like the CPU in the ECU is underspeced for the task at hand. It seems like it doesn’t keep up with rapid changes to the throttle. It’s like the TB reacts quickly but the timing and fuel adjustments lag behind a little.

I've had this noise in my BRZ since I took it off the lot. It only happens on very humid/ hot days. I always thought it was the throttle body opening suddenly. Maybe it isn't.. Haven't had any issues though.

Bravo!! I thought i got paranoic and filled the car with "race gas" (95 oct) because knock. Thanks mate, i feel like rubbish for spend 40 dollars at that pump.

Tip In Knock?!
 

The TB is almost silent. Go out to your car and turn on the ignition but don’t start the car. Now go all nuts on the throttle. You will hear the TB moving but it’s very faint. Definitely not loud enough to hear over the engine. You will sometimes hear air rush into the intake but this isn’t the ping/knock sound as heard in the video.

Right, I know that the air induction noise isn't related, but I have heard on numerous accounts what the OP is describing. Though, it only happens on WOT shifts for me.

Okay, I was just clarifying. I firmly believe the sound we are all hearing is knock. I just can't believe a modern car would knock right from the factory the way our cars do.

You're good! It is interesting, though. Has there been any reports where this leaded to serious damage (specific to our cars)?

So we all know about the early 2013 having the messed up transient retard table which was blowing injector seals. They fixed this in mid 2014. Well this table was updated again on the 2017 to pull even more timing.

Tor talks about tip in knock in this thread:
http://www.ft86club.com/forums/showthread.php?t=118629

He seems to have solved the knock by dropping the 2017 table into his rom. I think I am going to try this tonight and see how it goes. It does impact throttle response a little though. Hopefully it isn't unbearable. I am real picky about laggy throttle response. But if it prevents knock I will suck it up.

Bah! Nothing wrong with mixing in some good stuff. I bet you noticed the difference.

Stock tune in 2012-2016 cars will knock even on 93 fuel in 2000-4000 rpm under high load

2017 stock tune is better

Yup, at 6k rpm vvti kicked in yo

Agreed, watch the car's knock sensors.

http://www.ft86club.com/forums/showp...20&postcount=3


60k on stock early tune, almost 5k on the OFT tune, noise is exactly the same before and after.
Oh but now with added VVT noise as with the video in the OP.

I have recreated the sound while logging and there are no signs of knock in the data. But knock sensors aren’t 100% definitive one way or another. You can bog this car in 2nd from a dig and it will ping like a bitch and still not show in the data. I just can’t imagine what else the sound could be if it isn’t knock.

I will report back what impact the K00C transient retard table has.

A knock sensor will pick up a knock WAY before you can hear it. By the time you hear a knock your engine is pretty much fucked, which is why the piezo speakers that are knock sensors pick up any knock well before your ears can.

That noise isn't knock.

Why does it go away when pulling timing then? If it isn’t knock, what to you think it is?

I understand from speaking with more learned friends that the stock tune, at least for the zenki, is actually optimized for 94 octane.

And before this devolves into a panic, let's remember what the owner's manual says about it. On this page alone, the owner is reassured four times that a little pinging is normal. The system is designed to constantly look for the knock threshold and keep timing right up against it.

http://i.imgur.com/jmh9aE3.jpg

Tip In Knock?!
 

I just dropped the K00C transient retard table into my B01C rom and the ping has completely gone away. I will hold off final judgement until I get more miles on it. This car takes for ever to settle in after a flash so we will see.

Before I changed that table I did a log along with an audio recording on my iPhone. I started the recording and marked the start point with my defrost switch. So I should be able to line the data up perfectly with the data log. I haven’t played it back yet so I’m not sure if you can even hear the pinging. After a get some miles on this new flash I will do another log/audio recording to show the contrast.

Edit: I just played back the recording and you can faintly hear it. I was simply oscillating between 3500 and 2500 with the clutch in. There are a few of them where you can clearly pick it up in the recording. Tomorrow I will try to pair it up with the data somehow.

You make it sound like you engine is going to fly apart with a rod through the block if the knock is audible to the human ear. Have you never driven cars that dated back before knock sensors? If you bogged them they would ping like crazy but the engine doesn’t fly apart and the ECU had no way of correcting without the sensor.

Again, knock sensors are far from perfect. On the flip side you can have a rod bearing on its way out and the knock sensor thinks it’s detonating so it retards the crap out of the timing so much the car stops pulling. The knock sensor is bolted to the block. It picks up so much sound. It’s amazing it doesn’t retard the timing at random all the time.

This is not a 1979 Chevy with 9:1 compression ratio. Modern engines especially high compression engines like the FA20 don't take well to knock. That's not tip in knock the OP has and any knock is bad. If you can hear it, your engine is fucked already.

High compression ratios just means it’s more susceptible to knock. It doesn’t make it any more or less harmful to the engine. Knock on an old car is no different than a new car. You know what is actually happening when an engine knocks right?

Just a follow up. I am well past the learning phase after flashing. I also have an autox in on the car after the flash and the knock on shifts is still gone. Seems like the 2017 transient ignition retard table did the trick. I actually came across another thread about tip in knock on shifts also being solved with the 2017 transient ignition retard table. So that makes three threads on this topic all solved the same way now. Throttle response does seem impacted but not too bad. I am tempted to dial back the retard a little and see if I can find a happy medium where I eliminate the knock but don't hurt throttle response as much.