I have a 1981 240 turbo. I bought it in hopes of getting it running and selling it. It now runs but I still have a problem. It is running rough and I am getting some black smoke. I figure it is running rich. I have been trying to troubleshoot the frequency valve with not much luck. I have a POS Haynes manual. It might as well be for a Ford vehicle. I can't find my Frequecny valve relay or the Lamda ECU. Nothing in my manual matches my Volvo. In my manual it says I should have 12 volts on the frequency valve connecter when it is unplugged. I "had" zero volts. I just guessed and pulled a relay from under the dash. I resoldered some of the joints that looked shady and then put it back. I now have 9.5 volts but the engine still runs rough and rich. Should I have 12 volts? Can someone tell me exactly what this frequency valve should do and when? I get a buzz for two seconds when I turn the key on. When I start it I think it buzzes for a short time and then I can't hear it buzzing. I even took an automotive stethoscope and put it on the freq. valve. I heard nothing. A couple of other notes. I have replaced both fuel pumps, the fuel filter, the injectors, distr. cap and rotor button, and O2 Sensor. Also I need help locating the various parts of this system. Any help would be greatly appreciated.