Volkswagen Caddy with TFSI conversion would constantly get codes for a leak in the air intake system, a fuel pressure sensor malfunction, and fouled spark plugs. The ECU would constantly peg 27% on the short-term trims and trim to the maximum on the long-term trim. So basically, 50% close on. It turns out there's been a wiring cock-up during the conversion, causing the O2 sensor to scale incorrectly. The ECU thinks it's running lean at 17:1, but it's running an eye-stinging 10:1 (around 0.7 lamb