I also wanted to add, as far as checking for any vacuum leaks, or from the turbo all the way to the head, you can also use a propane torch, with the gas turned on, no flame of course, use a rubber hose connected to the tip of the torch about a foot or two, and slowly go along all of the vacuum lines, and pressure side of the intake air stream. If the engine stutters, or rises in RPM you have a leak at that point. I am sure that there are other ways about going this rout, though this is was came to my mind first hand. Did you by chance run the supra with out an air filter lol,
I ran filter less for about 2months, until it was time to clean the AFM, and seen all the junk and grime that was removed from the AFM.. Shocked I did not mess the AFM up :aigo: If you put new O-Rings on the injectors it certainly would not hurt, considering the mileage you said was on the engine. I also forgot to ask if you had the stock precat and secondary converter on the exhaust??? If so, slim though a possible chance that one or both of them may be clogged up.
White smoke: is normally a cause of anti-freeze burning in the piston cylinder. Normal ways for this to occur are a cracked head, blown head gasket,(warped head), or cracked cylinder block(normally uncommon).
What Black smoke means:
Black smoke: is often times a result of too much fuel and not enough air in the combustion chamber. In rare cases, it can be caused by weak fuel pressure causing fuel to 'drip' from injectors rather than 'spray'. It can also be caused by weak fire in the combustion chamber.
Gray smoke: is caused by brake fluid. It generally means that your brake master cylinder is bad, and is getting sucked through the vacuum brake hose.
What blue smoke means: is generally caused by the burning of an oil in the combustion chamber. Normal causes of oil getting into the combustion chamber are weak piston rings, bad valve guides, bad valve seals, or plugged up engines where oil is sucked back through PCV system, usually due to lack of oil changes.
The very best way to avoid bad colors coming from your exhaust is to keep your vehicle maintained. Upkeep of your vehicle is always a smart idea.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=21
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=22
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=24
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=31 Hope this may help out a lil bit or get you started on the right path of getting this fixed bud...