Just trying to dial my C4 Vette back in my tune after a cam swap back to my CC306 - Things I've changed are...

• Coil Location
• AC Delete & New Alternator Bracket
• Knock Sensor Module instead of On Chip Knock Filter ( I do see MUCH more start up knock with this - unfortunately I don't have a good $8d Memcal to try)
• I had issues with the Tach Signal and the Dash - would die over 3000rpm ECU always had/has good RPM signal - Dash seems to work now.

AFR is good and maintains 12.7 at WOT.

I had the limiter ($8d) set at 5800 and I was just seeing some knock retard before I crashed into the limiter. I was unsure if it was because I was at the limiter or actual knock so I raised the limit up to 6400. I pulled 4deg out from 5200.

I did several pulls up to the 6400 redline and sure enough from 5400ish I start having knock retard and it ends up pulling the MAX amount (I went up to 15* and it pulled it all). I also noticed what felt like an intermitant miss - very much like the rev limiter. I couldn't decide if it was me feeling the timing retard or if I actually have a miss. WB02 would go from 12.7 to 13.3 when this "Miss" happened which does suggest a misfire.

I can pull up to 5000rpm in any gear lots of load with zero knock detected.

From looking at the datalogs when I got home it almost looks like that when I start pulling some timing out of the spark table it actually starts to knock and it snowballs from there.

Part of me wanted to disable knock retard to see if I got a clean pull to 6400 but I couldn't do it. I can't hear any audiable knock though and I do know what to listen for.

Any suggestions?

 

Check plugs for detonation, harmonics can trigger KS.

 

All the plugs were a nice clean Tan colour apart from No7 which was sooty - I also noticed the gap was too tight (less than 0.20) I must have missed that one when I last swapped the plugs.

I've just redone my valve lash as last time I thought I'd try it a little slacker (1/2 turn) than the usual 3/4 turn I do. I figured that maybe they weren't tight enough and causing the knock sensor to go off.

I can get the knock sensor to pull 7deg just by giving it a quick rev stationary. I even set my Initial timing in the map to 15deg and it still KR'ed when rev'ed.

 

I forgot to say the Rotor was nasty too so I swapped in a new MSD one. I hope this may have been my miss?