Thanks Gunner,Tony & Mick, I have tested through a bit more thoroughly now & found that the needle lift sensor isn't giving a signal, but it definitely was when i first tested it.The funny thing is that the rev counter still behaves the same with the lift sensor connected or not,sometimes working ok sometimes not.The rpm signal must come from the CAS as when i disconnect it ,it loses the rpm signal. Why should the needle lift sensor effect the rpm signal?. The Cas wires are Yellow/green rings) earth pin 23 on ecu, green signal wire pin 25 on ecu centre pin on cas connector giving a sine wave of +5v-0v using chassis earth, red wire pin 8 on ecu switching between +10v - negative 5 volts needle lift sensor pins 7 red wire giving 12.6 v with sensor connected 13.7(nbv) disconnected pin 24 green wire . I will now get a new injector & hopefully it will be sorted, but i'm still not sure why it effects the rpm signal, unless the problem is related to the air conditioning. Thanks for your help, i will hopefully post a fix soon, Regards, Andrew