engine is running rich as it smells and pops

[ste drivs]

i have a 2000 mk4 golf 1.8 20 valve turbo,when i drive the car it smells like it is running rich or lean,and some times it pops through the exhaust like it is burning excess fuel of,the car has a dump valve and air filter fitted.dont no if this is the problem as they were on the car when i bought it,was also told it had been mapped and chipped so how will i no if it has,does anyone no why it is running like this or what i could do to sort it.thanks ste

[ste drivs]

no one then.

[Agreeable Slick]

Take it to a tuner, get a RR done, and then let them advise you on getting it mapped properly.

go to the remapping section and have a look through there.

[Kamshaft]

Definitely get it tuned on a dyno.  As you're in Manchester you could try Awesome or BHP UK, both have dynos and I've had good experience at both places.