Hi, what is the rectangle opening under the intake ports on the center iron for?

 

ACV port air.

 

story, I removed the block off plate on the LIM and under neath it was a big chunk of carbon or some dusty black gunk. Attempting to clean that out I accidentally knocked the pile of carbon down the LIM into this part of my engine.

How bad did i screw this up?

 

don't worry about it. worst case if you reinstall the ACV it may suck the crap into the check valve under the ACV and hold it open, but i doubt it will really hurt the smog pump anyways.

most likely it will sit dormant in the passages, since the exhaust will keep it in there. or it may get sucked into the exhaust in which case it will just exit the whole car. it's carbon, it's soft and chewy, it will only really semi harm a catalytic converter if you still have one.

 

phew, thought that gunk fell into the combustion chamber

 

nope, the passages lead to the exhaust port openings in the housings at the manifold and have to do many tight maneuvers before it could even think of escaping.