What could be the cause of the mid RPM knock?

[_Madman_]

I did a 3rd gear pull to see if all fuel upgrades are working ok on my car, and I noticed that there is some weird knocking going on at mid RPMs, and sometimes even mid throttle.

The log is done on a car with all the mods in profile, and T25 turbo at around 16psi.

P.S. Concerning logging, are there any other values that I should include when logging? AFR is ECU calculated, no idea what it does.

Knock uses scaling = knock * 10.

 

[GSXDNA]

I would log your fuel trim data, which will tell you if your ECU is adding or pulling fuel at any given time to compensate for a lean or rich condition. If you are running lean when knock occurs, you'll be able to tell that from the fuel trims.

Also, as for your mid RPM knock, I see that your timing curve has a spike in it right as knock increases. Looks like you might be running a tad too much timing. I'd try to make that peak in the timing curve more smooth.

 

[_Madman_]

I would log your fuel trim data, which will tell you if your ECU is adding or pulling fuel at any given time to compensate for a lean or rich condition. If you are running lean when knock occurs, you'll be able to tell that from the fuel trims.

I thought the fuel trims are used only in closed loop operation? Is it the LTFT I should be looking at? The STFT looks very similar to the LTFT graph below. Seems that LTFT is derived from STFT, and it flattens out on acceleration run.

Also, as for your mid RPM knock, I see that your timing curve has a spike in it right as knock increases. Looks like you might be running a tad too much timing. I'd try to make that peak in the timing curve more smooth.

Oh, I see. Is there a rule of thumb when setting up the timing?

 

[GSXDNA]

I thought the fuel trims are used only in closed loop operation? Is it the LTFT I should be looking at? The STFT looks very similar to the LTFT graph below. Seems that LTFT is derived from STFT, and it flattens out on acceleration run.

Ah, i thought you were seeing this knock in partial throttle closed loop. Yes, trims are ignored in open loop.

Oh, I see. Is there a rule of thumb when setting up the timing?

Every car is a little different, but in general, when i see a spike in timing coincide with a sudden appearance of knock, that's usually a good indication that the timing needs to be dropped a bit. I'd just pull the timing back a 1-2 degrees at that RPM range where the timing spike and knock spike are, and see if that makes it better.