[ZuMBLe]

Through my two years of tuning my car I've had the DAM drop once when I was playing with the AVCS table. I've had the car not take full KC but it never dropped the DAM. Recently my car started adding positive knock correction values in to the knock learning table. I've never seen it have so many positive values. I thought this was a good thing. Last night I did a 4th gear pull on the highway and the car felt great. Boost control was very good, EGTs were good. I went home to check the knock learning table and found all positive values except for a -0.6 in the lower end of the load/rpm region. Knock light never flickered during the pull. I checked the DAM and was very surprised to find it at .88. I've had pulls where the knocklite flickered a few times and it never dropped the DAM. What gives?

[crystal_Imprezav]

The IAM is controlled by a set of ranges in which it will be active or not. They are called rough correction ranges and are usually only active from something like 2000-5000rpms and something like 1-2.25 load iirc. My guess is that there is also a threshold where the bit is set or not from feedback by the knock sensor. If the bit is ever set in the range during those condition than your IAM will drop. It also has a set decrement in which it drops as well.

[ZuMBLe]

So you're telling me I got knock in the lower range which caused this? I would say the upper load range of my tune is very stable. What I did do is do a 5psi pull through half the RPM range on my way home which I normally don't do. What puzzles me is that I never saw the knock light flicker and the KC values I was seeing in real time on my scanmaster3 looked good the whole time.

Originally Posted by crystal_Imprezav

The IAM is controlled by a set of ranges in which it will be active or not. They are called rough correction ranges and are usually only active from something like 2000-5000rpms and something like 1-2.25 load iirc. My guess is that there is also a threshold where the bit is set or not from feedback by the knock sensor. If the bit is ever set in the range during those condition than your IAM will drop. It also has a set decrement in which it drops as well.

[waktasz]

I'm not exactly sure when the ECU decides to change the IAM, but just because you have positive KC values doesn't mean your car is happy. If your map calls for 10* and you are seeing 2*, that's probably bad. You probably know that already, but if not, it's something to consider.

[gabedude]

Rouch correction range is pretty narrow (IDRC the FXT ranges). It is better to knock at low load, low RPM (less damage) and have a global adjustment that affects the upper RPM where more engine damage can occur if it knocks (high RPM, high load). I have seen the IAM drop on the 32 bit ECUs, it is normal. It is setup that way to protect your engine.

[ZuMBLe]

Actually, I was seeing a KC of 8* through much of a RPM range out of a possible 9*but I found that 1 degree added to my KC table. So basically, it added 1 degree to KC and that resulted in the ECU not being able to take full dynamic advance. I didn't think it was such a big deal though. I've done multiple pulls where my KC was at 7 out of a possible 9 and the DAM didn't drop. Weird.

So the rough correction handles the + knock learning as well as the - knock learning. That's interesting info.

Maybe I need to bump the timing up 1 degree then reset the ECU so it doesn't have room to add the 1 degree so the KL will stay at 0?

Originally Posted by waktasz

I'm not exactly sure when the ECU decides to change the IAM, but just because you have positive KC values doesn't mean your car is happy. If your map calls for 10* and you are seeing 2*, that's probably bad. You probably know that already, but if not, it's something to consider.