I've got a 95 Nissan 200SX SE with the 1.6L DOHC motor. It was donated because of a bad head gasket diagnoses. I changed the head gasket and the leaking water pump. The head gasket was fine. The head checked out visibly and there was no other indications of a leak. The combustion chambers were equally and normally dirty. There was no "steam cleaned" pistions. It smokes badly intermittently. I can understand the diagnoses, because it pukes clouds of whitish smoke. It only smokes when warmed up. It might only smoke in closed loop, but I haven't been able to verify that. It smokes at an idle when revved. Clears up at speed. The smoke smells strange. It's not antifreeze. It's not really oily. It is not pulling brake fluid in the vacuum hose. It does not have a vacuum modulator to pull trans fluid in. The PCV was plugged, but cleaning it does not make a difference. It's non-turbo. It's not turbo seals. No one cylinder makes a difference. I pulled the plugs and injectors one at a time. No difference. It spark knocks badly when it's smoking. Not at all any other time. The timing advance goes from 0 to 64 degrees when it's not doing it, 0-4 degrees when it is. No fluctuation. it's either 0 or 64 degrees. All other data from the datastream is normal. Plugs are slightly sooty. None are oily, crusty or different from any other. There is dark black oily gunk coming from the exhaust. Just a little spray. The oil is new, of course, and the inside of the engine was sludge free. I'm stumped. I found one similar problem on the web in a ford/mazda Ranger, but nobody answered the guy's question. Any eye-deers?