I just recently bought a 94 civic coupe Ex from a garage, its been sitting for awhile. The car sounds fine when its on, but when i try to rev to 2.5 rpms and high it makes a clickin sound coming from the head. I took the head off and the valves look fine, so do the pistons. The engine is SOHC Vtec, the ECU it had when i bought was a GSR ECU. I think the guy who previously owned it was reving higher than what the engine can handle for too long. Theres oil almost all over the engine. The Head Gasket was also damaged.

 

maybe the previous owner had dropped a gsr engine and before he sold it, he tried to return the car to stock before sellin it, ergo thats prolly why you have a gsr ecu