+1 with Zach's comment. When it comes to engine detailing you have to be weary of your process.
My process consists of mapping the engine bay into parts and tackling it similarly to the panels of a vehicle. I do not hose, pressure wash or rinse down the engine bay.
1. Cover all electrical
2. Lightly Mist the Engine bay with water from a spray bottle. I personally used a pressurized bottle. The mist is much lighter.
3. Mist your favourite All Purpose Cleaner or Degreaser. I use Power Clean and if the engine bay is not in horendous condition I use Optimum No Rinse. I let the solution dwell for a few minutes.
4. I aggitate with a detail brush, Daytona Wheel Brush, EZ Detail Mini
5. Spray down cleaned area with Spray bottle or Pressurized Bottle.
6. Use a damp MF and wipe the area down.
7. Dry everything up, spray 303 Aerospace or Optimum Protectant Plus and wipe access protectant off.
Oh and if you have clearcoated or carbon fibre engine bay covers those can be removed and polished as well
That should be fun for you.