Black smokes indicates its running too rich -more fuel than air could be caused by the following

1.Excessive fuel pressure can be cause by restricted fuel return line
2.Defective Oxygen Sensors.
3.Leaking injectors and fuel pressure regulator.
4.Coolant temperature sensor out of calibration.
5.Restricted air intake system.

Answered by rasmataz
68 questions asked

thanks rasmataz,i've found a company who will connect it up to a machine on a rolling road which gives me a print out so i can see whats right and wrong saves hours of labour,but need to sort my alternator first,the battery light came on yesterday cant find any loose connections and my multi meter needs a battery,but thanks for the overview,keep up the good work,best regards dazza

Response from dazza
1 question asked

You're welcome and thank you

Answered by rasmataz
68 questions asked

update!! i've just serviced the astra,new oil and filter/fuel filter and removed and cleaned the MAP sensor which was clogged so much,but before oil change used engine flush,taken it for a run about 20mins opened it up and not so much smoke now yipeee

Response from dazza
1 question asked