How to identify ghost knock
 

I'm helping a friend tune his nearly stock S2000, but we are struggling with some knock counts on cylinder 2. The knock counts seem to happen in 2 scenarios. The first is at idle, and the 2nd is at 20-30% throttle between 3200 and 3800 RPMs. We have used the individual fuel trims to add 2% more fuel and -6* timing, but it hasn't helped. It seems to me that this is probably just some sort of rattle that the ECU thinks is knock, but I don't know how to prove it.

I believe the engine has 50-60K miles, but the head was just replaced with another used head last week. I'm not sure how many miles were on that head, but it had a bit of a "refresh" before it was installed. The only mods that I'm aware of are a TP and exhaust.

Any suggestions?

If it hasn't help any after adjust fuel/timing i would assume it's most likely false knock. Can you adjust the knock thresholds?

The knock tables can be adjusted to change the knock retard, but they don't seem to have any impact on the actual knock counts. The knock counter really seem pretty independant of the rest of the system.

Humm...that's pretty interesting. Can you guys hear any knocking from engine bay? It should eliminate any real/false knock in that range as well up to the new threshold level that you set.
Idk i might be wrong, since i'm still new to S2k.

Did the 6* that you pulled out have any effect on the knock count or raw knock voltage?

What are the timing values in those cells (for comparison sake)?

The six degrees of timing we pulled out and the extra fuel we added did not help.

No knock can be heard and the car seems to run fine. Ill have to look at the timing values when I get home tonight.

On one datalog, there were 21 knock counts all within about 4 minutes of driving.

it would be nice if hondata develop a knock indicator of some sort via one of the dash light. Like the CEL would blink indicating knock.

I know my old celica with the apexi powerfc, the CEL light would blink on each count of knock.

4mins 2x knocks hummm...what rpm that you see?
only way I can think of is check your plugs see if there is any sign of detonation.

Only between 3200-3800 rpm under 20-30% throttle and only on cylinder two.

I would have already checked the plugs but all the tools I had were stolen out of my garage a few days back. I'll try to do that tonight. Could a noisy injector be the culprit? I can swap them around to see if the problem follows that injector. :shrug:

One more thing to note..... I had gone back to the "stock equivalent tune" and was still getting knock counts on cylinder two.

Didn't you say that you were hearing some sort of rattly noise when you start the car? Did you order a set of the colder plugs? I have a set of Denso IK24's that you can try.