I'm wearing out my laptop datalogging and have been using the DLL software to review the logs.

I have been making small adjustments to the HO ignition maps and the car is running great. I'm still getting the occasional 1 to 2 knock counts with a few at 3 and these are for the most part now gone.

The tune is really good right now but I have noticed something in the logs from daily driving that I hope someone could explain.

I have been monkeying with the scatter graphs in DLL and have noticed something regarding timing that I hope someone can explain.

At light throttle (TPS around 27) and about 3500 RPM my car is showing several data points where the ignition timing is at 46 degrees.

This is only at very light throttle input, cruising speed.

The question I have is that the highest value anywhere in either ignition timing map is 38 degrees ?

I'm sure there's a logical explanation for this. I was just wondering what part of the ECU could be the source of the timing values being 8 degrees more than what is in the maps?

Thanks in advance,
Bob

Here's a screen cap of the scatter graph . . .

 

Disclaimer: I know very very little about all this so any of the following is simply a guess based on previous, firsthand and repeated board posts...


My guess is that under those conditions the entine ECU goes into closed loop, where it rely's not on what the tables say, but on what is best for fuel economy and low emissions...thus stoich and high advance, where it will advance as far as allowed (i've heard 50* maximum).

I remember seeing advance like that under the same conditions when we logged one of my friend's STi's.

 

There are some closed loop target maps that aren't documented nor is their functionality completely understood, one specifically is a timing offset (a range of timing used by closed loop from the actual value.)

 

MJ to the rescue

Thanks Jack. As I experiment more with the DLL software all I can say is what a great analysis tool for tuning.

 

DLL = Data Log Lab?

 

Yep, it's a great tool.