1993 Civic Cx with B18b1

Still debugging and rebuild, and swap install.

Engine was idling pretty well, but I noticed what sounded like a vacuum leak. I traced it to the brake booster. I removed the hose and plugged. The leak sound went away, but the engine revs dropped to about 100-200 rpms maybe slower, nearly stalling. Uncorking the brake booster hose the idle retrurn to a little above normal.

I'm wondering if the ecu needs clearing, if its the IACV, or if I should adjust the idle screw....

I'm also wondering if my brake booster needs to be tested to see if it will hold a vacuum.

 

There is definitely a vacuum leak at the bottom of the master power (brake booster) unit.

There is also a humming sound coming from the IACV with the key on position.

 

spray brake cleaner at the "infected area". If the idle drops then you know for sure its an idle leak.