I've got an 88 740 turbo that is blowing out very rich smoky exhaust.It starts ok but doesn't idle well and won't take any throttle very well. The boost gage indicates normal boost. I took it to an independent volvo guy and he checked it out and couldn't find any of the ususl problems i.e. amm. leaks. ox sensor ignition fuel press regulator. He thought it might be the ecu but he doesn't mess with that part in case he is wrong. I got a used ecu and tried it and it didnt make any difference. In reading the various forums and FAQ section I think it may be the coolant temp sensor. I measured the voltage between terminals 5 and 13 at the connector and I got just over 11.0 volts with the engine cold and an air temp of about 70 degrees F. with the ignition on and I checked the resistance and got .452 K. ohms on the meter with the ignition off. Am I doing the test correctly? Do these results indicate a temp sensor fault? I sure hope that this is the solution. I know the sensor is under intake # 3 and will require intake manifold removal. I'd just appreciate some confirmation that I'm on the right track before I replace it. I'll probably replace it anyway. Thanks.