Always suspected my 440 was running a tad rich. Well, now I now for sure! Hooked up an exhaust gas analyser and the CO readings are actually off the chart: around 12.5 - 14.5%, which probably translates to something like 9 AFR (10% CO = 10.79 AFR). Lovely.

This is an old Holley Pro-Jection 4Di EFI (digital, not the even older analog one). I'm really kinda fed up with it. Sure, I could replace the (narrowband) O2 probe and sealing the exhaust manifold would obviously help. I'd also need a laptop computer though which plugs into the ECU's serial port, oh and it has to run Windows 95-XP. Seems pointless.

Should I just go back to carb?