1hdft blow-by

[Sooty]

I've had my 1hd-ft for about 6 years and put about 60,000 kms on it since I've had it. Currently has 320,000 kms on it. It's always had a bit of blow-by, it may be getting slightly worse over time but I can't really tell. It blows a lot of black smoke under heavy load and smokes a bit at idle. It's always been a bit sluggish at take off but otherwise runs really well and the engine purrs like a kitten. Starts perfectly. I haven't noticed any change in performance since I've had it. It uses a bit of oil but only about 600ml every 5,000km. Had the valves cleared and injectors serviced last year, they didn't tune it at the time because they reckon the 1hdfts are a bit finicky or something. I didn't really notice any improvement in the blow-by after that. So I'm just trying to work out if there's anything I could investigate with the turbo or tuning. Or if it's most likely worn piston rings and I'm just looking at a rebuild.