Ok, I've heard knock before (not on my car thankfully) I've been in the process of tuning spark while datalogging after adjusting my CAS (base timing was off) . I datalog, and retard the timing to knock down the spikes.

I started thinking: I don't really know what knock looks like on a datalog. I know what mine says is knock, but I have a tough time believing a single random sharp spike is knock. Wouldn't knock be sustained in the log for as long as there was load, or at least until it moved close to a cell where the timing was more to its liking, not spike and disappear?

Anyway, can someone post a pic of a datalog with knock going on? I don't want to pull spark unless i"m sure there is knock. I checked my plugs after a run yesterday, and they looked fine.

 

Since no one want to chime in, I'll throw up some pictures. The first one is what looks like real knock sustained over a longer period of time.

Here is the random spike that I'm wondering if I should mess with the timing or leave it be.

Question is: How would all of you tackle this problem> lower timing over entire region that I see knock, or just reduce timing at the large spikes and see what that does. I lowered timing across the entire region.

 

What RPM is that at? Mine does it between 4K and 4500K almost every time at any MAP pressure. I ignore it now.

 

The knock in the first image is about 5200-6500 at 180kpa
The second image (single event) is 4843 164 kpa.

I really think that I am going to start ignoring loan spikes when datalogging, and only adjusting timing if I see a pattern like the first image.

 

Would you mind posting/sending me those log files? I could really use them for a class project.

 

Sure, I'll send you the logs. Is there something in particular you are looking for in a log? Send me a pm with your email. Do you have dataloglab so that you can open the log, or are you looking for still images?

 

Build yourself a set of detonation cans. Electronics will tell you what they think is knock. I love my Knocksense (it's great when I'm on track and not really listening to the motor), but if I'm actually tuning or listening I'm wearing my cans.