After i originaly thought i fixed the 17705 by cleaning and resetting tb as no code for a week , i checked and it had reappeared
after doing a smoke test looking for any leaks i found light smoke coming from the end of the suction jet pump below the inlet . i previously looked at this as there was a small amount of oil residue around one end but thought nothing of it . anyway fitted a new one which is slightly modified on the end casing to the original (which was 10yrs old) so that it wont leak oil vapour again and after 3 weeks there is no code return and ive done lots of miles in that time . it may well appear again but i think ive cracked it this time !!!
at least the new smoke machine (£600) has done its job for the 5th time so far
