View Single Post
Old 11-02-2007, 07:31 PM   #3
Scooby Specialist
Member#: 110304
Join Date: Mar 2006
Location: Crestline, CA
2004 Volvo S60R
No more Subie


Originally Posted by Toolz View Post
Is it safe to say that running osecu stage 1 with boost gauge and lots of logging would tell me if my setup is safe.? Like if I was running lean in a area, it would produce knock right? So I would see that on the IAM and KC values?

You generally don't want to see a whole lot of negative KC value. It's a major indicator of knock. Broxma mentioned that it would be hard to tune negative KC out completely... You would have to have a very conservative tune. Modern ECUs tend to sort of "probe" for the best timing possible by adding as much timing as aloud before detecting knock, that way they are always running at an optimal timing advance (within the boundries of the timing maps of course).

I run a fairly conservative vf-39 tuned based on ev8siv3's vf series enginuity map and I rarely see much in the way of negative value, and when I do it's fairly low and brief... like no more than -3ish. I think the most I saw was -5 briefly around mid/high 4000's rpm range in 3rd gear as boost was climbing to 16psi after letting my car sit idling with major intercooler heat soak then a hard run, just to see a worst case scenario.

IAM is also a good indicator of how "happy" your ECU is with knock. If it's below 16, you'll probably want to either pull a little timing or richen the mixture... this is where a good wideband helps to see if you're running lean when you experience knock. Some folks seem ok with an IAM of 14-15, but I can't imagine that it's a good thing.

Disclaimer: I'm no expert on this subject, so take what I say with a grain of salt... and any gurus are free to correct me if I'm mis-informed.
* Registered users of the site do not see these ads.
jhargis is offline   Reply With Quote