my adaptive spark / octane scaler settings

[Boost]

Can someone please take a quick look at my tune, I made very slight changes to B6215, B6220 & B6221 in an effort to encourage the computer to move towards the high octane table since I always run Chevron 93 premium. I noticed in my log that it is using the high table 100%, but when it hit KR of 1.8 degrees, it did not move at all in the direction of the low table (stayed 100%). Would like to make sure I did not hinder the ability to effectively move in the direction needed to avoid repeated knock and retard. Or is a few isolated 2 degree retard too little for me and the pcm to be concerned with? Thanks, tune attached.

[swingtan]

If you only get a single hit of KR, or get only a small amount of KR, then the octane scaler may not actually move. It's not a bad thing, it just menas there was not enough KR to start the octane scaler moving.

Simon.

[WeathermanShawn]

Boost:

B6223 determines the actual amount of KR to 'Enable' the Octane Scaler.

The greater the differential between your High and Low-Octane Spark in effect determines the 'working range' of your Octane Scaler.

Personally, I like keeping the Scaler as active as possible. It seems like a very smart engineering concept to mitigate recurrent KR. If you want to have the Octane Scaler recover quicker (to High-Octane) just manipulate B6213 to a lower MAP.

Even though you are running 93 Octane, legitimate KR can occur..especially as IAT's climb. You could always manipulate KR attack and recovery rates if it is a real concern.

But as stated, lowering B6213 will bounce you back to High-Octane Spark very quickly..if that is what you want..:).

Good luck..

[Boost]

Thank you Simon and Shawn! I value your knowledge and time and glad you responded.

Here are two logs from yesterday, driving aggressively on the way to and from work. I logged LOTS of good data. Picked up some KR, and will try to tune it out. I am trying to figure out if it is false or burst knock. I will assume that it is legit and try to get rid of it as I incrementally advance elsewhere. I have found so far that timing makes my particular engine responsive and efficient, although I understand there may be no or negative gains even before KR. The goal is 0 KR.

The first one is in the morning after it rained. Truck felt strong, I am thinking because the air had not warmed up yet even enough for the rain to evaporate and cause our famous humidity. Also, the sense of danger from traffic and wet pavement, maybe, like the little sideways action on the expressway at 70...

The second one was on the way home, fully warmed up maybe even heat soaked a little. Slightly different traffic and hot, humid air. Truck felt very weak!! :(
I am thinking if it makes that much difference, perhaps my IAT and other modifiers aren't tuned properly? I know it needs lots of work, I'm on it.

Any thoughts please?

[WeathermanShawn]

It does look like legitimate detonation KR, though overall it is relatively minimal. It looks like on your afternoon drive that you got a single 4-5 degree KR event at WOT.

Personally, I would work a little more on your High-Octane Spark. It is those areas from .40-.60 g/cyl where it looks like your Spark remains high. At .68 g/cyl it drops dramatically. I would probably blend those areas a little more.

Yes, there are techniques to recover KR quicker and lessen the amount. In my tune, I have increased the KR recovery rate by 500%. That is all I have done. Everything else I have left alone.

On a side note, you are still getting a nominal +LTFT's. Getting those negative will not only help your overall fueling, but will also put you in a better Spark g/cyl load. Your PCM will 'compute' a greater load. That may solve a lot just by doing that.

Overall, not bad. Get your LTFT's in line, and perhaps smooth or blend that mid section of your High-Octane Spark.

[swingtan]

+1 for the fueling. Consistent positive LTFT's means that the base fueling tables are set too lean. Given that the LTFT's are somewhat "course" in their application, it's possible you are running lean while in PE mode. Get a WB hooked up and dial in the air flow tables.

Simon

[Boost]

Thank you both again. Your advice is on point and makes a lot of sense. I have headers and aged narrow band sensors and suspected lean condition under load. I will can now try to make improvements in this specific area and learn from it before asking more complicated spark questions.

:cheers: