Hello All
Quick update on this one in case anyone has any final words of wisdom, as my beloved Lexus is close to going to 'live on a farm.
To recap, my IS220D gets c. 26 mpg. It smells of diesel whilst running, and occasionally smokes very heavily (white).
Based on some of the advice here, I have (since the last post) had the 5th injector swapped out. Twice. Despite an initial positive increase in mpg, it soon dropped back down again and I'm back to where I started (except a bit poorer obviously, though found a great value Toyota specialist that works from home in Guildford, so not too bad).
But here's the thing - when the mechanic disabled the 5th injector entirely, and I drove it around the block / up the A3 for 20 mins or so, I was hitting well over 40 mpg. So surely it IS the 5th injector, or something to do with it.
The only other thing I can think of is to replace the wiring, as per the advice in this thread, comment from 2016... https://www.lexusownersclub.co.uk/forum/topic/107523-potential-fix-for-is220d-white-smoke-smells-of-diesel-poor-mpg/?&page=3#comments
Not sure how I will do that - the clever chap sounds like he remade the cable himself, which is far beyond my skillset!
Any further advice, please, would be so much appreciated.
Ian