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Old 01-20-2016, 02:22 AM   #517
Sojhinn
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Join Date: May 2012
Drives: Limited Red 6MT BRZ
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Quote:
Originally Posted by KoolBRZ View Post
@shaynek contacted me about fixing a knock problem that was dropping his IAM when he boosted at low rpms. The first thing I thought was "Try my tune instead of the OFT tune", but it knocked just as bad as the OFT tune. Well, in theory, I should be able to plant my foot at any rpm without getting engine knock, if the tune is right...

So I started with Timing compensation and looked at the MAP comp table. It looked like the more pressure it got, the more it changes the timing. That should do it, right? But, in the description in RR it says in parenthesis, "(clutch depressed)", see pic below. Well that isn't going to work on an AT, and sure enough, it didn't.

So I looked in the Timing Advance section and saw the Knock Correction Advance Max A table, and thought "Let's give this a try."

I rescaled it to go to an Engine Load of 4.0, since that was as high as I saw in my logging, and lowered the cells where I saw the most knocking. This is only my first try at modding this table, but it did virtually eliminate knock. 3 out of 5 logs had no knock whatsoever, and the 2 that did had only momentary knock, not long enough to drop the IAM. See the logs here, http://datazap.me/u/koolbrz/log-1453...ata=1-2-8-9-10

If you're getting knock between 2000 and 3000 rpms when boosting heavy, (I saw Engine Loads as high as 3.82, and boost as high as 4 psi) you'll need to change this table to eliminate knock.

If anyone has a dyno, they can optimize this map to get the most out of it. Just start with a table full of 3's, then log the knocks and pull timing from those cells, bump the other cells to 3.5, log and pull timing, bump up to 4, log and pull etc...

Hey kool nice job spotting that. Were you getting knock on your system as well?


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