I have answers at last, took the 850R up to Moss Vale in the highlands this morning to Allan Mackay Volvo service centre, its where Ive been buying parts for a few years and their service centre is a group of blokes who like the older volvos as well as new ones and have been watching how the 850R is coming together.
Even though the Lambda light had gone out I wanted to know what alarms if any where still sitting there waiting to be fixed.
Thankyou to those in the thread who helped educate me on this.
Hr & a half later & I have a full print out of issue , qoute for parts and an explanation as what a lambda light covers and in this case , how the knock sensor affects the running of the motor.
All of this information fits in with what the cars been doing.
At last answers, other than that it's driving very nicely