I just noticed that my car (Rover Si620 model) started bringing out dark thick smoke, and was consuming excess fuel.
We changed the nozzles, air flow, plugs and the car started moving well but the smoke still persist. Then we the mechanic asked the rewire to check what else could be the cause, then he said, water entered the brainbox and it is not controlling the fuel consumption again and that's why it was still smoking.
Then we change the brainbox, still the fuel consumption and smoke still continues.
Now I noticed again that the fuel pump is not working fine as the car takes longer to start after it has been used for long and parked, I will need it to cool for like 15-30mins then it will start again.

Experts, I need counsel on what to check? Or I just sell the car (but my fear is selling the car and the buy will get a solution to it, just like my previous car, would always trip off on motion (timing belt will always cut, not knowing that the engine seal was dripping oil into the timing belt, making it to slack and the belt would cut then car would stop working - the buyer told me that after fixing the engine seal, it stopped and I have sold the car).

herojid:
I just noticed that my car (Rover Si620 model) started bringing out dark thick smoke, and was consuming excess fuel.
We changed the nozzles, air flow, plugs and the car started moving well but the smoke still persist. Then we the mechanic asked the rewire to check what else could be the cause, then he said, water entered the brainbox and it is not controlling the fuel consumption again and that's why it was still smoking.
Then we change the brainbox, still the fuel consumption and smoke still continues.
Now I noticed again that the fuel pump is not working fine as the car takes longer to start after it has been used for long and parked, I will need it to cool for like 15-30mins then it will start again.

Experts, I need counsel on what to check? Or I just sell the car (but my fear is selling the car and the buy will get a solution to it, just like my previous car, would always trip off on motion (timing belt will always cut, not knowing that the engine seal was dripping oil into the timing belt, making it to slack and the belt would cut then car would stop working - the buyer told me that after fixing the engine seal, it stopped and I have sold the car).

Scan scan scan

Check your engine coolant sensor

herojid:
I just noticed that my car (Rover Si620 model) started bringing out dark thick smoke, and was consuming excess fuel.
We changed the nozzles, air flow, plugs and the car started moving well but the smoke still persist. Then we the mechanic asked the rewire to check what else could be the cause, then he said, water entered the brainbox and it is not controlling the fuel consumption again and that's why it was still smoking.
Then we change the brainbox, still the fuel consumption and smoke still continues.
Now I noticed again that the fuel pump is not working fine as the car takes longer to start after it has been used for long and parked, I will need it to cool for like 15-30mins then it will start again.

Experts, I need counsel on what to check? Or I just sell the car (but my fear is selling the car and the buy will get a solution to it, just like my previous car, would always trip off on motion (timing belt will always cut, not knowing that the engine seal was dripping oil into the timing belt, making it to slack and the belt would cut then car would stop working - the buyer told me that after fixing the engine seal, it stopped and I have sold the car).

Scan the car. It is most likely going to be the oxygen sensor that is the culprit. The black smoke is evidence of an extremely rich fuel mixture. Whenever there is any issue with fuel mixture, first thing to always check is the sensor that controls the mixture, that's oxygen sensor or air/fuel ratio sensor as others may call it. However, you need to scan to be 100% sure.

Please check your airflow meter. Fuel/Gas/ Spark troubleshooting

herojid:
I just noticed that my car (Rover Si620 model) started bringing out dark thick smoke, and was consuming excess fuel.
We changed the nozzles, air flow, plugs and the car started moving well but the smoke still persist. Then we the mechanic asked the rewire to check what else could be the cause, then he said, water entered the brainbox and it is not controlling the fuel consumption again and that's why it was still smoking.
Then we change the brainbox, still the fuel consumption and smoke still continues.
Now I noticed again that the fuel pump is not working fine as the car takes longer to start after it has been used for long and parked, I will need it to cool for like 15-30mins then it will start again.

Experts, I need counsel on what to check? Or I just sell the car (but my fear is selling the car and the buy will get a solution to it, just like my previous car, would always trip off on motion (timing belt will always cut, not knowing that the engine seal was dripping oil into the timing belt, making it to slack and the belt would cut then car would stop working - the buyer told me that after fixing the engine seal, it stopped and I have sold the car).

SCAN!!!!