stevebbc

iTrader: (4)

should i be looking at spark or fuel. Z06 cam, hand ported 806 heads. runs good from 3 to 6k rpms.

gametech

iTrader: (1)

You should look at your VE tables. At over 3k rpm, the tune reverts to MAF input to calculate airflow. This is likely why the engine runs more smoothly. Your cam and porting have likely altered your VE to the point that your tables need to be tuned. Both fueling and spark are affected by reported airflow. Since the tune uses the VE tables during transient throttle situations, once you hit a rough patch you can cause enough oscillation to never get to a steady state that allows the MAF to control reported airflow. You must have heavily ported those heads to get much of a problem with such mild mods.

stevebbc

iTrader: (4)

Thanks for the reply. Heads were done locally by a guy that is supposed to really good. Other mods include LTs, no cats, rear O2 delete, LS6 intake. and rebored block. I copied a tune from HPT repository of a Z06 car with almost identical mods but results were the same. I've been logging STFTs and copying them over to the VE tables and smoothing with some slight improvement. Tune and log is attached if anyone has time to look over.

gametech

iTrader: (1)

Attach a log of your problem areas. This will allow much better diagnostic input. Don't expect many responses until the weekend, as the storm situation is making power and internet on the east coast a bit spotty.