whiteflash

My roommate is more familiar with tuning STi's / Evo's, so before he really starts to push the limits of my tune we want to make sure we've got a proper grasp on how the knock control works. Evo's / STi's have an advanced map, as well as a knock map overlaying on their base bap. The s2k's configuring seems very archaic in comparison. I apologize if my thought process is a little scattered.

So I want to understand if I have the concept correct.

There of course is the knock sensitivity map. This determines what area's of your rpm/throttle % are more or less sensitive to knock. You can tune area's that you think might be seeing ghost knock sensitivity (but not necessarily knock count). Although if your suspicious of a ghost knock count you could lower the sensitivity to help determine if it is or isn't ghost knock.

From analyzing this is what my thinking is; please correct my understanding of how the maps work in conjunction. Ignition timing maps, as well as fuel timing are locked (Non-learning). There is no seperate knock map. Only the sensor that approximates the octance / AFR and how often it should be igniting.

Essentially this is how I'm see'ing it break down evaluating my log, and I want to see if I'm beginning to see the light:

At stock the ECU has a map that is very well tuned out of the factory, for a universal 91 octane. As you add an intake for example (without tuning), your fuel/ignition timing maps are locked. Now you're bringing in more air, with the same amount of fuel and running leaner. At this point your knock sensor forces a retarding of ignition, at locations in the map based off of more or less a specified algorithm. Since it's not active, and is really just a "best guess effort" by your cpu, these might be overly retarding, or under retarding.

In relationship to JUST knock retarding and keeping everything else the same, you would lower timing in places where it's retarding, and could possibly advance timing where no knock retarding is being done, until you have the best ignition map w/ 0 knock count and 0 retarding.

I understand that is NOT the way to tune, but it's the only way I can try and formulate my understanding of knock control in its simplest way.

In summary;

The knock control does not work 'seperately but together' like the STi's, where they feed information back and forth. The knock control is conjoined directly to (or inside) the ignition map definitions and it's relationship to the ecu's approximation of octane and afr.

Thanks

Gernby

I honestly don't even understand what you are asking. Hondata provided some explanation of the Knock control system in a thread, but I haven't seen anything helpful about the knock tables are for in the FlashPro.

https://www.s2ki.com/forums/index.php?showtopic=745922

ace123

I can't exactly answer your question, but maybe this will still be worth posting. I'd read the Hondata post from gernby's link first.

With how Hondata describes knock and what I've seen from my dozen or two datalogs, recorded knock in the logs doesn't have a great correlation to the trends in the knock % chart--or even A/F ratios, to my surprise. I suppose, with enough true knocks, you could find where you are relatively too far advanced and retard timing there while advancing it elsewhere for each throttle position and RPM level (and fuel level setting?), but I don't think you would have much success doing that with knock %. And obviously tuning by inducing recorded knock counts at every RPM and TP would be foolish, as you said, but I don't see a flaw in the theory.

On a related note, (and you have probably already figured this out, but others read these posts too,) to tune out knock in this car, you can adjust individual cylinder fuel and ignition timing. This helps ensure knock level is the same for each cylinder. It does not appear to depend on RPM or throttle position at all--so I think it's just a global offset. Hondata's help shows them using this feature. My ignition and fuel are both at +0.5, -0.5, -1.0, +0.5, and it seemed to do a bit better I haven't knocked recently, so it's not fine tuned yet, but it's better than 0, 0, 0, 0.

whiteflash

I haven't encountered a knock count yet, however I'm see'ing knock retard. Which I'm guessing is a false positive. I'm actually pretty much ignoring knock % as it seems to be a completely funky value that really seems completely meaningless. As someone said in another thread they've seen 80-90% yet no knock recorded, yet got a knock count at 18%. Unless these values work backwords (i.e. 0% = guaranteed knock) I can't see an understanding to look at that portion of the graph at all.

My tuner (roommate) is extremely picky about understanding every aspect of the ecu's operation, even if it's just simple theory that may only relate to a microscopic gain. I suppose that's why he's hitting 310whp/340wtq in his STi w/ only a turbo inlet and exhaust. We've seen STi's that are 'tuned' with a laundry list of mods making less power.

So any question he asks, is pretty much up to me to find out the answer since he's doing it in his spare time and I'm obviously not paying him. While I know how ignition and afr work together, I'm completely foreign to examing these graphs and tuning. After about 30 minutes of looking at them I started formulating theories on how our ecu calculates certain values, so I just figured I'd run the thought by and see if I'm dead off or if what makes sense in my head actually makes sense.

Appreciate the feedback

Gernby

I datalogged some knock counts at an autocross this weekend. The knock seemed to be due to really bad heat soak (IAT's greater than 140* F), so I had to make some changes to my air temp ignition compensation tables.

Here is a close-up view of Knock Level, RPM, Knock Count, and Knock Retard. As you can see, knock retard immediately jumps 1 degree when it detects the knock. I had 6 knock counts on a single datalog of 4 autocross runs, and every knock count was immediately followed by a 1-2* jump in knock retard. However, the knock retard seemed to reset after throttle was lifted. For example, if I got a knock while at WOT at 6500 RPMs, then the knock retard would increase by 1* up until I let off throttle at 8K RPMs. The next time I hit 6500 RPMs at WOT, knock retard stayed low unless I got another knock count.

What I find particularly weird about this datalog is that there is nothing evident in the knock level at all that indicates a knock.

TheNick

I'm currently having all kinds of issues where the ECU is getting false knocks from loud valves. Its retarding a lot of timing above 7k. Valves are adjusted perfectly fine (per OEM spec) but they are still relatively loud.

Gernby

The Honda spec is pretty big for valve clearance. I keep mine adjusted .001" - .002" tighter than the minimum spec to maximize lift and duration. They are also quieter that way.

BTW, how do you know that it's your valves causing the knock counts?

whiteflash

I dunno if this is at all possible, but gernsby we have semi-similar mods and I was wondering if I could see one of your street datalogs (or calibrations). I just wanna see what your numbers look like compared to mine. I seem to be running quite rich, and I wanna compare the differences. I'm not gonna steal, just compare. But I'm not sure if the files are locked to the unit or not.

Thanks

TheNick

Its quite obvious due to the number of knock counts. I can't go tighter than minimum spec due to rules limitations.

I'm getting up to 9deg retard at 5500 and near 5deg at 7k.

The "counts" are all under 10 at this point - but if you plot Count on the Yaxis and RPM on the Xaxis - there are at least 50-60 data points for a couple WOT pulls in a period of 16 minutes.

Gernby

If I had paid for my calibration, I wouldn't be so willing to share it, but I don't mind sharing what I have right now. Send me a PM with your email address, and I'll shoot it over to you.

Nick, just to rule out the valve adjustment as a possible issue, are you sure you are measuring the clearances at the right location? From personal experience, I know that some Honda's have clearances spec'ed between the cam lobe and rocker while others spec the clearance between the adjuster screw and valve. When I first adjusted the valves on my '02 AP1, I measured between the lobe and rocker, and wound up setting my clearances WAY TOO BIG. I lost quite a bit of power and my valves were really noisy. IIRC I gained over 10 ft-lbs on the dyno when I fixed it. If that's not the issue, then I would start getting concerned about a valve problem. Have you done a leak down test?