I have a 95z that I am tuning in Open Loop Speed Density mode.

I am having weird knock. Sometimes it does it and sometimes it won't. It will be a little such as 0.x sometimes high as 12.

I only fill up with 91 - 93 Octane.

The mods done to the car are:

Pacesetter Long Tubes
!EGR
!AIR
!AC
160* thermostat
TB Bypass
Rebuilt the heads with new valve seals and stainless steel valves.

I can upload a datalog and my tune if anyone is willing to look at it and help.

Thanks.

 

Are the long tubes touching the chassis in any way(even under load)? Are those all the mods? No roller rockers? With no more than what you have....why tune it in speed density? Given the mods, there is no need to touch the stock tune....except maybe to get rid of the SES light that your emissions deletes might cause and cooling fans for the new thermostat temp.

 

Running 'Open Loop' can be a crapshoot . W/O O2 correction any sensor problem or fueling problem goes uncorrected by the PCM. You first have to see if its vibration as ACE stated, or pre-detonation (real knock). Analyze the data logs and see if knock count is increasing at a specific RPM and MAP, If so that could be a lean spot in your VE tables. You could also drop timing 5* at the RPM and MAP knock point if there is one to test things out. If it's at different engine loads it points to vibration. Remember PCM remembers knock conditions and retards timing at that point to avoid a re-occurring, so look at KC incrementing , not retarded timing for real data. Data logs in open loop will not show much as the BLM's are not reporting AFR (rich/lean) which can pinpoint knock. As ACE asked why are you in 'SD-Open Loop with your mods ?