Borescope Inspection of the Intake Manifold of a KIA 1.6 Engine
This borescope video was made for a practical reason, not just for the sheer joy of scoping things: I was curious about how much carbon there was inside the intake manifold of my 2016 KIA's 1.6 GDI engine. For this video, I used the side camera on my DEPSTECH DS-450 borescope. The built-in side camera has its own LED light for good illumination and eliminates the need for a 90-degree mirror attachment. It's quite a nice feature for such an affordable borescope.
In and of itself, carbon in the intake manifold isn't that big a deal unless the deposits are heavy, in which case the manifold should be removed and cleaned by a professional or a skilled amateur mechanic. Light deposits really don't matter because they don't disrupt the airflow in any way.
As it happens, there wasn't very much carbon in my car's intake manifold at all. I suspect a big part of the reason is because I clean the induction system before every oil change using a good intake cleaner like CRC Intake Valve and Turbo Cleaner (my personal favorite), Seafoam Intake Valve Cleaner, or Berryman Intake Valve and Combustion System Cleaner (pricey, but probably your best choice if you also have carbon buildup in the cylinders or around the piston rings). Keeping your car's intake system clean from day one will help prevent carbon buildup from ever getting to the point that it affects performance.
I also use a good quality synthetic engine oil (Castrol Edge Titanium is my current favorite) to minimize hydrocarbon offgassing, and I inspect the PCV valve regularly. The PCV system is one of the main ways the carbon gets in the manifold in the first place, so making sure the PCV valve is clean and functioning properly helps reduce and prevent carbon-related induction path probems.