L31MaxExpress
I'm Awesome
Not sure what value you are looking at there. Perhaps commanded air/fuel. A vortec does not have widebands so it is blind to the actual air/fuel ratio. Commanded air/fuel will drop over ~90% throttle to about 11.5:1 from memory. You need to look at both your long and short term fuel trims. I would check idle, just above idle and at 2,500 rpm no load. Then put it in gear and power brake it to 1/4- 1/3 load for a couple of seconds, watching the trims. Don't stay on the throttle long as you are building heat in the torque converter very quickly. You just want to get the load up for a second and see where the long terms are reading under load. Also need to look at your Bank 1 and Bank 2 Sensor 1 aka upstream 02 sensor voltages. They should be toggling around 450mv in a fairly quick oscillation at idle and just cruising along. When you step into it hard, they should jump up to the high 800s to low 900s and stay parked there. If they dip much below that say 700 mv, the engine is running lean. If they drop under 100 mv the truck is extremely lean. Look at your MAF signal. At hot idle should be around 1 gm/sec per liter of engine size, so about 6 gm/sec. When you start accelerating yhe engine the airflow should smoothly rise. If you snap the throttle it should a sharp, steady incline. Stock engine would show around 200-220 gms/sec of airflow at WOT and high rpm. Probably more like 150 gms/sec at 3,000 rpm and WOT. Just some reference points.
