Knock control observations

[teders]

Yesterday i was doing a bit of extra spirited driving, and saw my knock control metric get up to the highest i've seen it yet, .72. Usually i drive my car really easy and keep knock control at around .49, with the occasional jump up to .53-56 after multiple WOT pulls. Yesterday however i had to be somewhere in a hurry, and i was speeding for significantly longer and more aggressively than i probably ever have in any car. Not something i take pride in, but yesterday it really had to be done. That being said as nervous about police and the well being of my car, i'm not going to pretend i didnt enjoy it.

One thing i noticed was that knock control actually would come down if i maintained an RPM range of between 4-5k in 5th gear (cruising at 80+ for several miles), which i consider to be aggressive driving, and that knock control would only ever really climb after WOT through the RPM range to redline. Obviously that is more aggressive and so not really any surprise to me that k-con would go up. Knock control seemed to only be able to drop after the car was driven for an appreciable distance. Once i hit traffic towards the end of my drive (not stop and go, but slow coasting around 20-30 mph) knock control would drop less rapidly than it would at higher speeds covering more distance, which seems counter intuitive to me.

This is the first car where i've been able to know what my knock control is (thanks ktuner <3 ), so i dont really have anything to compare to. Would anyone with more knowledge of the dynamics of knock control care to share with me what they know? Specifically i'm curious as to what factors will cause knock control to increase/decrease.

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[360glitch]

I notice the most significant k.con drops when boost pressure is above zero. I've also noticed that because the Si motor targets boost quicker than the base 1.5, k.con will decrease quicker. Once you realize how it works, you can easily manipulate k.con to drop very quickly, assuming you don't have any real problems.

 

[teders]

Interesting, good observation. So really its all about maintaining a positive boost pressure. If you maintain a lower K.con, does that mean that you are experiencing less knock events or merely that your engine is being less hindered by knock control?

 

[360glitch]

Interesting, good observation. So really its all about maintaining a positive boost pressure. If you maintain a lower K.con, does that mean that you are experiencing less knock events or merely that your engine is being less hindered by knock control?

Knock control will increase when you have knock. The tricky part is that it will increase for other reasons as well, and there is no documentation publicly available that tells us why.

If knock control is at a minimum, the engine is not experiencing knock.

 

[kshawn]

Do a slow pull holding at 2-4 psi 4th-5th gear. That's how I get knock control to drop back down. On a base stage 2 tune And catless downpipe. I can do 2 pulls before it leaves .49 after that I saw .52 after 5 pulls. My car is begging for more but waiting on a clutch.

 

[gtman]

So... I have Hondata and K control seems to stay around .54 as the low point on 93 octane. Ktuner's lowest is .49...

Is Hondata a bit higher as a margin of safety against knock?

 

[LilToTo17]

So... I have Hondata and K control seems to stay around .54 as the low point on 93 octane. Ktuner's lowest is .49...

Is Hondata a bit higher as a margin of safety against knock?

Technically the lower the better but it depends on octane fuel.

Here’s what Vit officially said, “The Knock Count value on this ECU is worthless. It doesn't track actual knock -- I've induced audible knock on our test vehicle and knock count stayed at 0. Yet at other times it would go up while shifting the vehicle. Pay attention to Knock Control, it is the more important value. And what this value does will depend highly on what the tune is setup to do. For a stock style tune that is designed to run on 87 octane and premium (91+) you'll see around 1.0 on 87 octane and closer to .5-.6 as you get up to 93-94 octane (not all premium fuel is the same).

On something like our Stage 1 and Stage 2 tunes we've designed them to run on 91-93 octane, so on 91 octane expect to see closer to .9 and as you get to better premium grade fuel you'll see closer to .5 - .6.”

 

[Metal_Hatch]

@maddmatt02 made a video on YouTube about how to speed up Knock Control learning, helped me out a lot.
Link below:

 

[360glitch]

So... I have Hondata and K control seems to stay around .54 as the low point on 93 octane. Ktuner's lowest is .49...

Is Hondata a bit higher as a margin of safety against knock?

I've asked about this a lot and my understanding is that you should consider Hondatas .54 and Ktuner's .49 as equivalent. Knock control is almost better looked at as a trending value, rather than it's value at any given time. For example, 0.60 is not necessarily a bad number, but if you see it go from 0.49 to 0.60 (or similar) under light throttle conditions, you probably have a problem.

 

[ParkwayDrive13]

I've asked about this a lot and my understanding is that you should consider Hondatas .54 and Ktuner's .49 as equivalent. Knock control is almost better looked at as a trending value, rather than it's value at any given time. For example, 0.60 is not necessarily a bad number, but if you see it go from 0.49 to 0.60 (or similar) under light throttle conditions, you probably have a problem.

Would you feel that it would be a problem under part throttle, or WOT? I've always understood that if k.control goes up sharply under WOT its a problem, not so much under part throttle. Am I wrong with my understanding of that?

 

[dc2turbo]

Would you feel that it would be a problem under part throttle, or WOT? I've always understood that if k.control goes up sharply under WOT its a problem, not so much under part throttle. Am I wrong with my understanding of that?

it shouldn't go up with partial throttle unless its making full boost where TPLATE is at 90% or higher.

At partial throttle, it can go WOT even if you are only giving 25-30% throttle.

 

[ParkwayDrive13]

it shouldn't go up with partial throttle unless its making full boost where TPLATE is at 90% or higher.

At partial throttle, it can go WOT even if you are only giving 25-30% throttle.

Hmm. Interesting. I'll have to datalog mine then. I've seen my kcontrol go up during part throttle (approximately between 50%-60% Tplate[ill have to re-verify that]) and go back down/stay the same during WOT. (Currently stock, with Ktuner/VitTune Stg1) Could be many reasons, but this has sparked my curiousity. Thanks for the info

 

[gtman]

I thought it was the opposite where K. Control spikes up right after WOT and then slowly lowers back down or is that incorrect?

 

[kshawn]

Accelerating in to high of a gear, for the speed, will anger knock control.

 

[360glitch]

Here's an observation for you, that I've never heard anyone else mention before. It may be a little "deep" for the average user but many will understand. As best I can tell, while in open loop, the ECU will NOT increase the knock control level regardless of what terrible things may or may not be going on inside your engine. If you don't know what open loop means, or the various fuel statuses that Honda uses, there is a fair bit of documentation available on the web.

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