Last time I cooked one I banked my coals to one side of the grill and seared the tenderlion by turning it .25 way every 2 min until I went all the way around. Then I moved the tenderloin over to the cool side and stuck my temp probe in. I pulled it when the probe hit 128. I wrapped it and let it rest 30- 40 minutes.
It was on the med rare side and everyone ate it.