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Old 12-12-2012, 10:02 PM   #1721
reid-o
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Member#: 103631
Join Date: Dec 2005
Location: Mililani, Hawaii
Vehicle:
2004 STI
Gray

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Quote:
Originally Posted by Maxwell Power View Post
First off, Bariga loves to mess with ****. That's the number one reason.

Second, with the Vipec knock control system, none of it is preset. All of it is the responsibility of the user to get calibrated properly. We did a handful of work on it on the road and dyno, but it was still lacking some. Talking with Link and tearing apart more OEM roms combined with me using my knock block amplifier has opened my eyes more to the Subaru knock strategy than before. Turns out nothing I thought was wrong, it was just incomplete. I didn't have an understanding of the severity of our valve train noise and why subaru put so much emphasis on #4 until I put the headphones on.

Short story: you can't hear cylinders 1, 2 or 3 with the knock sensor over the valvetrain. That's why Subaru doesn't bother trying. They put more timing on 4 and make it the first cylinder to knock so they can adjust global timing using the IAM (or DAM) based on that cylinder's trend. Once the ecu figures out cylinder 4, they know the other cylinders are safe.

The trick is to get the Vipec to do the same thing properly with one exception. Program the Vipec to detect cylinder 4 properly in the event of knock and yet still make sure the other cylinders aren't knocking.
I haven't looked at the link software, but I'm guessing that there is no gain on the knock signal? I'm interested in the knock block now. I'll go look it up. Is the value that its converting the analog to digital for processing as opposed to just applying a threshold to the analog signal?
I've found the same by logging raw knock voltage on the ems 2, and even with the raw voltage amplified to get some readings to pass 1v its difficult to see deltas unless the knock is severe. Actually I don't even know its severe. I just know that I can't make out sharp deltas unless they're really high.
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