I recently swapped a d16y7 block and trans into my my 99ex Civic coupe I have the original d16y8 vtec sohc head cleaned and decked and leak checked. And put it back together. I have notable top end noise and idle surge after it heats up. I just found that the knock sensor was plugged in but broke away from the block and hanging. Would this cause my problems or should I get a new iacv and a valve adjustment?
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Fix the knock sensor and bleed the cooling system.

Also post all CEL codes.

Then go from there.

 

i can't remember if the Y7 has an oil control orifice in the block or not. this could be an issue if so.

old thread for reference

can anyone confirm? OP, was this checked for when assembling?

 

Did you use the y8 mani with the air holes? (without plugging them?) But I can never remember which years this effects.