My V90 significantly lacks power especially when going uphill. No codes, no overheating, just no power! We attached a 'live read' scan tool to the OBD2 port and noticed that the ignition timing jumps around all over the place from an expected 14 degrees advanced to 0 and occasionally to a degree or two retarded!\n\nHowever just sitting in the driveway the timing curve seems to be what I'd expect - 9 degrees advance at idle and then a steady rise to a max of 30 degrees at 4000 rpm.\n\nSome history. I bought this car with a seized engine and replaced it with a used one from a 1997 960 which had exactly the same power issue as described above. Unfortunately the water pump failed, broke the timing belt which of course locked the engine up. I managed to find another 960 engine (1996) and before installing did what I should have done before and replaced all the timing belt components. This engine came with knock sensors so I did not transfer from the previous engine.\n\nWhat could be the cause of the erratic timing only when driving?