Hello first of all, I have the following problem with my Mazda 323F BG 1,6(65KW/88PS): If the engine is warm, about 45min drive, it starts to stutter at 4500 – 5000 rpm and in the stationary gas the engine is really draining off. A start of the engine is then difficult, because this does not start immediately and you notice that the mixture is too fat, also strong smoke development on the exhaust. After a diagnosis it was established that the water temperature sensor is defective, has changed this and let the control unit reset, so that was or is unfortunately the error not fixed. In a new diagnosis no error could be determined, but the problem persists! My guess was that the control unit is defective and has bought a used one! The control unit, which was in Mazda the marking B61KF and that bought the marking B67K, what is the difference between the two? Can one install the new without consideration? (Hab das nämlic h made and the engine starts and could not detect any problems yet!) Since the Mazda was bought used, I don’t know what was done before! Is there a way to determine which control unit belongs to the Mazda (read that there are two different ones!)? Or is the problem of the engine completely different? Thank you for your help and forgive me if I couldn’t find anything about the search! Greetings Darkfox