VersaTune User Forum

Hi,

New user here, recently installed Versatuner and flashed the stage 1 tune (manual transmission stage 1 91US 95EU) from the easyflash tune database to my gen 3 mazda 3 2.0l skyactive g.

After driving 50+ miles i have started to take some logs to check MAF calibration. One of the parameters I have been keeping an eye on is knock retard. I have seen the knock retard is ranging from +0.35 to -5. Could someone please confirm I have understood this value correctly. Negative knock retard is safe, the ecu is advancing the ignition timing when the values are negative? And positive knock retard is dangerous, the ecu is retarding the ignition timing when the values are positive?

Thanks

Paul

Under normal driving circumstances none of these values is dangerous in any way. You would have to worry if you saw more than 2-2.5 degrees of KR at high RPM (4500-5000+) and high throttle application (WOT) on a turbo vehicle, or more than like 5 on a NA. That "knock retard" parameter in this case are just timing corrections based on various parameters (steering, throttle application, fuel octane, and so on), that being the reason why the correction varies up and down.

Thanks for your reply

So positive values are what I should be concerned about if they start creeping up? Negative values are safe?

Paul H wrote: ↑April 18th, 2024, 10:12 pm So positive values are what I should be concerned about if they start creeping up?

...If they start creeping up quite a bit and in high throttle/ high RPM situations, not at cruising.

Be nice if the devs would chime in on this. To me, it appears that negative knock retard value results in a reduction of ignition timing. Mitigating knock using common methods at those load and RPM points results in a reduction of negative knock retard.