So I got the wideband hooked up and I am in the process of trying to validate the stock LT4 VE settings.
I created a speed density tune with the following modifications:
- Disabled the MAF.
- Disabled COT Protection.
- Disabled LTFT by setting Min ECT to 491.
- Forced open loop by setting the o2 readiness voltage to -2000 mV.
- Set the Open Loop Gas EQ Ratio's to 1.0 across the board.
- Disabled DFCO by setting the enable temps to 284 degress F.
I let the car warm up using the regular tune and then switched to the speed density tune. I started the car and it doesn't idle great. The stoich AFR is 14.1, the commanded AFR is 14.1, and the wideband reads the AFR at 14.8 to 15.0. With slight throttle (850 RPM or so), the commanded stays at 14.1 but the wideband jumps to 16.0+.
Out of the 3 stock LT4 tunes I have, the virtual VE tables are identical for 2 and the other is very close. I'm having a hard time believing my VE config is that far off considering I have a motor, airbox, etc. that's identical to the CTS-V.
I've read that a vacuum leak may be the cause, but I'm not aware of anything that would be leaking.
A previous post mentions camshaft angle, for now I still have stock settings. I wasn't sure if this could be skewing the AFR that much at idle or not?
What other factors am I not considering?