Engine speed ROC for Knock but not CLL?

[DerekAE86]

I guess most of the time for a large ROC in RPM to happen there will be a large delta for TPS input or resulting MAP.

But is there a reason why Engine speed Rate of Change is monitored in addition to TPS and MAP deltas for Knock control but not CLL?

[Adamw]

RPM ROC is only used for the normalised knock mode which is comparing the noise level of the current combustion event to an average noise level for the same cylinder that has been learnt over several previous combustion events.  So if there is a big change in RPM, the noise level of the current combustion event may be significantly higher than the learnt value that you are comparing to. ROC is used to trigger the "delta gain" to temporarily increase the knock threshold for a few cycles until a new average is learnt. 

For CLL, there is definitely some fuel puddle volume change with airspeed, which is loosely related to RPM, so I expect there would likely be some lambda disturbance related to a high RPM ROC, but I haven't personally noticed any need to factor it into CLL conditions yet.  

 

[DerekAE86]

That's fair. I just thought it might have some uses as a lockout value more so in the decreasing RPM situation where you get spikes in Lambda that usually come from the TB snapping shut on a gear change or engine braking.

Correct me if I'm wrong - but the TPS and MAP delta lockouts are only for positive changes?

[Vaughan]

On 8/14/2023 at 7:39 AM, DerekAE86 said:

but the TPS and MAP delta lockouts are only for positive changes?

Just checked the code and yes