The car starts half the time. (CF = 50)
There appears to be gas in the carburator. (CF = 75)
The plugs do not look very dirty. (CF 20)
The car was tuned fairly recently. (CF = 70)
In addition, the car rides pretty rough, but the user is not quite sure what CF to assign to this symptom. Is there a borderline CF for this symptom? That is, is there a CF that allows for a diagnosis, and yet CF's below (or possibly above) would not? If so, identify the borderline value and explain why the system behaves this way. If not, explain why the CF for this symptom is not relevant.