I've been chasing a problem for months related to a suspected missfire/shudder between 2000 and 3000 RPM, I don't have any codes but I know its fueling related, this problem disappears after 3000rpm. I've also noticed that when the car is cold the problem is not noticeable, by the time I finish my drive and the car is warm I can hear a difference in exhaust tone and can feel the vibration. So far I've done multiple Calc Vets (VET-VEN are very close)and recently done a RAFIG. I have two wide bands installed that show around 14.5 when driving, the car does run a bit rich in open loop but once in closed loop (warm) AF's look OK, this may be due to my Cam overlap and am working on this issue.

Based on my observations this problem has to be heat related, I'm waiting for a new set of plug wires but am trying to figure out if there are other temperature related fueling parameters the need to be adjusted.


Parameters adjusted so far;

IFR
Calc VET
RAFIG (desired airflow)
Spark Tables


Motor specs;
LS6 Block
Camshaft 226/229 .575/.578 116 LSA
LS6 Intake
85mm Professional Products Throttle Body
Hooker Headers
No Cats
Denso Iridium plugs gaped at 40