Helping a friend out with his POS daily. Car is a 2000 civic LX sedan, just put a D15 (B7 I believe) into it because he got a good deal on it and the motor was in great shape. Swapped out sensors and got it running off the OBD2 D16Y7 ECU, no codes anywhere, passed NYS inspection. Ran like a sewing machine when it was put in, still runs great, but it gradually started burning coolant. The coolant smoke doesn't come out of the tailpipe in pulses, so it seems like its not a leak on only one cylinder. It was bad enough to kill an O2 sensor (completely fouled with greenish-white crusty shit). Plugs are white.
The weirdest thing is that the previous motor that was put into this car, a Y8, ran great (except for a knock) for about 8,000 miles before it started doing the same thing. The only parts that have been re-used between the two engines are the electrics, header, throttle body, and cooling system.
Only things I can think of would be something in the intake manifold leaking, or he somehow fucked something up to the point where it would completely trash a head gasket across all 4 cylinders (cooling system overpressure?).