Ignition timing doesn't follow the map from 2400-3000 RPMs

[Gernby]

I have an S2000 FlashPro FP-S2K-US-30040, and am using the attached calibration. When I datalog at WOT (attached), my ignition dips down beginning at 2400, bottoms out at 2800, then goes back up to where I think it should be by 3000. I can't find anything that would cause this in the calibration or the datalogs. The knock retard is pretty constant, so it's clear that it isn't the cause.

My igntion value at 2800 for the load value in question is 22.6*, but the IGN value in the datalog is only 9*, and the K Retard value is 4*. Where is happening to the other 10*?

Even with the "Stock Equivalent" calibration, the IGN value at 2600 RPMs is only 7* with a K Retard value of 4* despite the timing map showing a value of 20*.

This also coincides with a dip in torque, so I really want to figure this out. Any help will be appreciated.

[Spunkster]

It looks like throttle tip in ignition retard, this is normal when you stab the throttle to help prevent detonation.

[Gernby]

Sorry, I see why it would look like that, but it does it even if I go straight to WOT well below 2K RPMs. See this "Stock Equivalent" datalog where IGN drops off after 2300 RPMs even if I go full throttle at 1300 RPMs. Yes, I know that it isn't good to lug the motor ... :|

[Gernby]

FWIW, none of the IGN values below 3K really match up with what is in the calibration. It looks almost like none of those values are really being flashed.

[Gernby]

No thoughts on what's causing this? I was able to smooth out the IGN curve by creating a 6* spike in the timing map at 2800. It doesn't look good in the FlashPro Manager screen, but it sure works better on the road. My torque curve is now flat from 2K-3K instead of having a 5 ft-lbs dip at 2800 RPMs.

[Gernby]

Hondata or Spunkster,

Could you please let me know if you're looking into this issue?

[Hondata]

If the stock eqivilent calibration produces the same results then the behaviour is that which Honda intended.

[Gernby]

If the stock eqivilent calibration produces the same results then the behaviour is that which Honda intended.

This is a frustrating answer. The whole purpose of the FlashPro is to change the behavior that Honda intended.

[Gernby]

To my surprise, my IGN values at 2800 RPMs advanced by about 8 degrees after reducing the knock value in the knock control table from about 715 to 630. It seems that Honda implimented some sort of dynamic knock retard in addition to the "long term" knock retard, which did not change based on my adjustment. However, this did cause a knock count.

[civicRSA]

I was having the same problem on my FN2 at low rpm. It was solved with a combination of lowering the knock sensitivity tables and retarding ign. very slightly.

[VitViper]

The knock tables are a well kept secret. From experience I've just been automatically pulling about 20% out of the knock tables and tuning ignition for no knock. This is particularly noticeable on the low cam and with noisy setups like S/C Si's. Noise from the blower will drive the knock sensor crazy and I've seen 18-23* knock retard being applied, which hits the other extreme and the ECU registers knock counts simply because the engine is not getting enough timing.

[Gernby]

Here are some pictures that show the issue and resolution. The upper line in the "Timing and Knock Retard" graphs are the IGN value, and the lower line is the Knock Retard value.

[Gernby]

The knock tables are a well kept secret. From experience I've just been automatically pulling about 20% out of the knock tables and tuning ignition for no knock. This is particularly noticeable on the low cam and with noisy setups like S/C Si's. Noise from the blower will drive the knock sensor crazy and I've seen 18-23* knock retard being applied, which hits the other extreme and the ECU registers knock counts simply because the engine is not getting enough timing.

That's good to know. I've kind of been stumped about what my goal should be next. I've tuned around the excessive knock retard by advancing the hell out of my ignition timing maps, but that didn't seem like a very "elegant" approach. Now I feel like it would be better to tune the ignition timing maps and knock control maps so that I have the "best" IGN curve with no knock retard. However, should I then slowly increase the knock sensitivity to the point that it just starts to pull timing, then back off a bit?

[civicRSA]

This is a difficult subject as why would you want to see knock retard when the motor is not actually knocking. Maybe Hondata can help here.

I tend to think that as long as I am not going to change fuel octanes then I will tune my ign. timing safely for 0 knocks and then adjust the knock sensitivity tables so that I get max 2-3 degrees retard on low cam.

WOT I would not want any ign retard if there are no knock counts.

Thanks to Vit for the tips. My car is way better at part throttle now.

[Hondata]

The short answer is that knock retard is not related to the amount of knock.

A longer answer is that knock retard will sometimes vary with knock, but over a fairly long time period, and not by much.

The knock sensitivity will determine the amount of knock retard, but does not affect the knock count. The ECU has MBT ignition table (mean best torque = the ignition table we usually edit) and also a calculated ignition limit for detonation. The lower of calculated ignition limit and MBT ignition is used, with the difference showing as knock retard. Changing the knock sensitivity table alters the calculated ignition limit and so can reduce the knock retard. Also the amount of knock noise will shift the calculated ignition limit up or down as the ECU estimates the fuel octane. I wish that Honda had used a better knock control method, but I suspect that the best had already been patented by other companies.