black smoke from my car

#1
i brought a second hand golf gti x reg its a 2.0 115 bhp. took it in for mot and it failed on emissions they were at 11% i dont know much about cars and the last time i went to dealers i walked out after paying 780 on vauxhall so i dont wanna go there.

the mechanic says its air flow meter any ideas guys

the revs are also not very steady they dont jump about too much just a touch and he says that is because of the air flow meter
went to another garage and he says its the oxygen sensor..

im not sure wat to do now
any help will be very appreciated
 
#2
it sounds like this problem is causing your fuel system to run rich, hence the black smoke.

your mechanic might be correct as usually a faulty air flow meter, which is giving the computer incorrect readings, causes this kind of problem. however leaking vacuum hoses will also give you these same symptoms.

double check all the hoses that lead to your throttle body, and intake manifold for cracks, and insure that all the clamps are secure. im not too familiar with the engine bay in gti's but you may need to remove some plastic covers to gain access to the throttle body and intake manifold. to check the hoses, just go along each hose and give them a gentle squeeze (car ignition is off).

have your mechanic check your fuel pressure regulator with a fuel pressure gauge to ensure that you have a number within spec of that of the manufacturers.

it doesnt hurt to change the o2 sensor as well as it is a maintenance item anyways.
check your oil.
 
#3
black smoke = burning fuel/ running rich

does your get upto temperature? Possibly the thermostat gone - this means it doesnt heat up properly, therefore it overfuels !

as for the unsteady revs, is this when the car is idling? if so, make sure the car is cold, take of the radiator cap, and start the car, leave the car running untill the fan comes on, this will get all the air out of the system, then top up the fluid and put the radiator cap back on.
 
#4
spoons said:
it sounds like this problem is causing your fuel system to run rich, hence the black smoke.

your mechanic might be correct as usually a faulty air flow meter, which is giving the computer incorrect readings, causes this kind of problem. however leaking vacuum hoses will also give you these same symptoms.

double check all the hoses that lead to your throttle body, and intake manifold for cracks, and insure that all the clamps are secure. im not too familiar with the engine bay in gti's but you may need to remove some plastic covers to gain access to the throttle body and intake manifold. to check the hoses, just go along each hose and give them a gentle squeeze (car ignition is off).

have your mechanic check your fuel pressure regulator with a fuel pressure gauge to ensure that you have a number within spec of that of the manufacturers.

it doesnt hurt to change the o2 sensor as well as it is a maintenance item anyways.
check your oil.
helpful. :thumb:
 
#6
spoons said:
have your mechanic check your fuel pressure regulator with a fuel pressure gauge to ensure that you have a number within spec of that of the manufacturers.
you a mechanic or something? fuel regulator was the problem :thumb:
 

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