I just finished installing some mods on a 2019 CTS V, and when I took it for a drive, it threw a P228C and a P0089 and went into limp mode.
Here are the mods
Headers w/o cats
2.3 Upper Pulley
8.6 Lower Pulley
Snow Dual Nozzle Meth Kit
DSX Aux Fuel System
DSX Flex Fuel Kit
Pro Speed Heat Exchanger
When I cruise the car through the gears on the dyno, I can watch fuel rail pressure drop almost to zero and the it throws the codes. I flashed the stock tune back in, minus the fes fuel settings, and it still did it, so I don't think it's anything I did tune-wise.
Has anyone else come across this? I've done other cars with similar mods, but never ran across this problem before. I attached the log of it doing it below.
fuel pressure drop.hpl