Have a vehicle in the workshop which has a lumpy idle, best described as hunting. Initially we thought it was the usual rocker cover problem as when the oil cap removed it seemed to smooth out, but still not right. Fitted a new rocker cover, and after various test's it is something to do with a fuelling issue. Bank1 sensor 1 is not switching from rich/lean and the Mv figure is staying high. It does switch but no where near the frequency it should. The reason I know this is having had another vehicle in, a comparison check was done and the donor vehicle was switching constantly as expected. The O2 sensor was removed from the donor vehicle and made no difference to the problem vehicle. I forgot to say the its staying Rich most of the time, in fact this is confirmed by the amount of soot on the original O2 sensor when removed. Also a emission's test has confirmed CO high and the other readings out to what they should be. Compressions have been checked and new plugs fitted so far. I would like to check the injector timing/duration but Modis does not appear to have the function as I am starting to think may be the ECU is not sending the signal to lean of the fuel, but just a guess at this time. Has anyone got any ideas as to what to test next and also how I could check the injector duration, any help appreciated.