toyota hillux year 2006 engine 2kd-ftv excessive black smoke at the tailpipe why it never use to be like this

Black smoke indicates that the air/fuel mixture is too rich (too much gas and not enough air). Check the air filter, check temp sensor, check fuel pressure regulator. If the check engine light is on, have the computer scanned for trouble codes. Most parts stores will do it for free and it should identify where the problem is coming from.

thanks very much , am student of the penn foster college and i newly start out working at work shop and i think ill need help

Glad to help. Let me know what you find.

plz can you tell me which scan tool is the best one to buy , because i would like to buy one some day

could the turbo cause this problem

As far as the turbo, I doubt that is the issue. What I suggest is to go to a parts store for the scanner. Now keep in mind, not all scanners can read all codes. On that can read them all will cost a ton of money. If you want a basic scanner that can read engine codes, you should be able to get one at a parts store for under 100 bucks. I'm not allowed to recommend brand names, but they all work.