Limit ignition trim

[Simon_s13]

I was on the dyno this morning and I found that the car was losing power. I went through the log and I found "Limit IGN Trim  -5".

it may sound stupid but why does the ECU activate it?

The engine wasn't knocking, ECT and IAT ign trim were off. 

After a few runs I have seen it twice.

Thanks in advance

 

605-1.llg

[Adamw]

All limiters include an optional retard when active.  In your attached log it is the RPM limit that is active at the 19sec mark.  

With advanced mode turned off the default trim is -5 (5deg retard).  If you dont want retard when the limit is active then you can set it to advanced mode and the trim is user configurable.

 

[Simon_s13]

Thanks for your quick response Adamw,

The RPM limit is 6500 rpm as you can see on the attached image

Why does it activate the limit at 6087rpm? 

I'm a bit confused with this.  

[Adamw]

33 minutes ago, Simon_s13 said:

Why does it activate the limit at 6087rpm? 

Looks pretty close to 6300RPM just a touch before that to me.

 

With advanced mode off, the default limit control range is 200RPM, this means the limiter will start fading in 200RPM below your set limit (ie 6300RPM).  When the RPM drops below your limit the cut percentage is removed at the exit decay rate - which is 5%/20ms in default mode.  The ignition trim will be active the whole time the limiter is active.  The point where your cursor is on the time plot with the RPM at 6087, the limiter is still active because it is being decayed.  

[Simon_s13]

On 3/9/2024 at 10:04 PM, Adamw said:

With advanced mode off, the default limit control range is 200RPM, this means the limiter will start fading in 200RPM below your set limit (ie 6300RPM).

Ok thanks for the explanation I understand it now.