Preheat a grill to 350 degrees F.
Place corn and chiles on grill, and grill until corn is partially charred on outside and chiles are fully charred on outside. Transfer both to a platter. Peel the outer skin from the chiles and remove stems and seeds, leaving only the tender meat of the chiles.
Remove corn kernels from the cob with a knife or spoon and then place in a medium bowl. Dice chiles, red pepper, and onion and then add to bowl with kernels. Add cilantro and lime juice. Drizzle with olive oil. Add salt and garlic powder, to taste. Thoroughly combine and then refrigerate for 2 to 3 hours before serving.