Vauxhall Astra smokes when changing gear and also loses power

Assume it's a diesel? Could try changing fuel filter.

What colour is the smoke? Have you checked oil and coolant level?

My dad says try using a diagnostics to see if there are any components failing?

Good idea from your dad , saves guessing. Could also check all hoses/ pipes for leaks or collapsing.

Good idea from your dad , saves guessing. Could also check all hoses/ pipes for leaks or collapsing.

The smoke is black, the EML light is on all the time, had a diagnostics done and there was a few faults but the mechanic said he checked all the faults when he serviced the car and found none of them being faults anymore. It's getting really frustrating, someone said it could be the EGR but they are not a mechanic!!!

Surprised your mechanic did not check the Egr valve .

Me too, I'm gonna go back when kids go to school it wasn't smoking when I took it for service, checked oil and everything not too much in lol,

Black smoke is the most common smoke emitted from diesel engines. It indicates poor and incomplete combustion of the diesel fuel. There are many causes, including…
Incorrect timing

Dirty or worn injectors

Over-fuelling

Faulty turbocharger (ie not enough air to match the fuel)

Incorrect valve clearance

Incorrect air/fuel ratio

Low cylinder compression (eg sticking piston rings or worn components)

Dirty air cleaner

Restricted induction system (eg system too small or kinked inlet piping)

Other engine tune factors

Poor quality fuel

Excessive carbon build up in combustion and exhaust spaces

Cool operating temperatures

Obviously, worn or damaged components must be replaced, and the earlier you identify and fix the problem, the less damage will be done. Keep on top of engine tune issues, including valve adjustments, and regular servicing of air, fuel and oil filters. Do not buy fuel from suspect outlets. Dirty components, such as injectors can be easily restored to full cleanliness by using an effective and reliable fuel system cleaner. If you choose from our range of products, Cleanpower is what you need.

Cleaning of internals of engines has usually only been possible at overhaul, however, Cost Effective Maintenance provide two products to enable vehicle and equipment owners to quickly, safely and cheaply restore full cleanliness to combustion and exhaust spaces (FTC Decarbonizer) as well as piston rings, oil pumps, oil galleries, oil coolers, piston skirts, valve gear, etc (Flushing Oil Concentrate).

Black smoke is high in carbon or soot, which is an undesirable product of diesel combustion. Now, the combustion of diesel is a complicated process of breaking down the various hydrocarbon fuel molecules into progressively smaller and smaller molecules, by burning in the presence of oxygen. The main and ideal end products of combustion are CO2 and H2O (carbon dioxide, the greenhouse gas and water). It is believed that the last step in the process is carbon monoxide (the poisonous gas) to carbon dioxide. This is also the slowest step by far, and when combustion conditions deteriorate some upstream bottle necking occurs in the chain of combustion reactions. This results (according to some authorities) in polymerization of smaller partly burnt molecules into much larger ones, which become visible as soot, or black smoke.

Thanks for all your information on my problem, it is the EGR valve that's gone, will be getting fixed this week, so I'm a happy lady, thanks again xx

Glad you got to the bottom of it and car getting fixed , thanks for the update .