Running into issues with my LDG Z-11 Pro II and 130ft end-fed half-wave. Problem: Tuner finds a match on 40m-10m but completely fails on 80m - just cycles endlessly and gives up.

Setup: FT-991A → Z-11 Pro II → 130ft EFHW with 9:1 unun, 25ft of RG-8X. Most tuners are less efficient at low impedances - could this be the issue? SWR analyzer shows 8+j45 ohms at 3.8MHz. Any suggestions before I try a different matching strategy?

That impedance is brutal for most tuners. The common "T" network tuner is most efficient matching around 1000 ohms, while very inefficient at 2.5 ohms. Try adding some feedline length to transform that impedance higher, or consider a different unun ratio.

Had the exact same problem with my Z-11 Pro on 80m EFHW. You must apply power to the tuner for it to tune - try AM mode at 20W and hold transmit for the full cycle. Also make sure your RF power is adequate - these auto-tuners need juice to work properly.

By taking the tuner through all the bands, you train it for when you return to that band. It memorizes the settings. However, your 8 ohm impedance is probably below the Z-11's matching range. Consider a 4:1 balun instead of 9:1 - might bring that impedance into a more workable range around 32 ohms.