Article in English: Only light one side of the grill, whether it's a gas or charcoal grill. Lightly oil the grate with cooking spray.  If using a gas grill, light one side of the grill and close the lid. Let it reach 350 degrees Fahrenheit (180 degrees Celsius). If using a charcoal grill, pile the coals to one side of the grill in a large heap. Light the coals, then let the flame die down until white ash forms on the surface of the coals. Close the lid to keep heated. Combine the chili powder, black pepper, and garlic powder. Rub the seasonings evenly over all sides of the roast. Blending the spices in a small dish will help you apply the seasoning evenly to the roast. Transfer the seasoned roast to the unlit portion of the grill. Cover the grill and cook for 1 hour.  Stick a meat thermometer into the center of the sirloin tip roast to test its internal temperature. At this stage, it should be 140 degrees Fahrenheit (60 degrees Celsius). Monitor the temperature of the grill as the meat cooks to make sure it stays relatively consistent. Use a basting brush to evenly apply 1/4 cup (60 ml) of the barbecue sauce over all sides of the roast. Grill for additional 10 minutes. At this stage, the meat should be 150 degrees Fahrenheit (65 degrees Celsius) inside. Remove the meat from the grill and transfer it to a cutting board. Allow it to stand for 10 minutes.  Create a tent out of aluminum foil and place it over the roast as it stands. When done, it should have the internal temperature of medium doneness, 160 degrees Fahrenheit (70 degrees Celsius). Cut the roast across the grain, forming thin slices. Place these slices in a large and top with the remaining barbecue sauce. Toss with tongs to coat the meat, and serve.

Summary in Chinese:
预热烤架。 给肉调味。 将肉放在烤架上。 刷烤肉酱，继续烤。 静置。 切片，加入剩余的酱，即可食用。