With these older engines we have to have a more comprehensive way to repair/tune them. Some engines I have seen reciently are in horrible general condition. This thread starter is starting to describe problems like low power as well. When you read the voltages from the glow plugs you start to get some real idea of whats is really going on in there. In reality the same method used to service really large diesel engines. All you are really reading is the heat level in each individual cylinder converted to milli volts. It is not rocket science. They should be simular in a good running engine. When they are not you have problems and their location and probable cause indicated. For engines with single problems you usually will catch it but if say you have four overlapping problems how do you differentiate them? Without a lot of experience or a fat wallet to throw money at them you just do not. Unless there is a usable system for amateurs like myself that will work. That is the thrust behind reading the glow plugs or otherwise known as the milli volt method. . Even the possible restoration of a good power balance is in sight now at a very reasonable cost unless your engine compression is all over the place. These cars are getting older and older. Things are aging at the same time other things are becoming truly defective. There are already too many 123s out there with less power and fuel milage than they should be getting plus a lot with rough idles and noises. For example lets say he changes the injector out and adjusts the valves. Where do you go after that without a workable system if the problem is still there? What about his low power? Sure it could be as simple as filters. But as these cars get older and older it will not be them in far too many cases. As I see it we either develop a workable system usable by the majority of members. Or there are going to be a lot of cars around with problems unresolved but just lived with. Yet in reality so easy to rectify if we have a workable system that is used. We do have the system. It is getting people to apply it and think about it that is going to be the problem. I would drop this approach if there was any other system in sight for indirect non computorised diesels like the 616 and 617 series. It has always exceeded expectations when used so far.