SamG_Marea said:
Where would i go for an emissions test and approximatley how much are they?
Do you think about i should be getting a lot more than 120-130 miles for £20?
an emisisons test can be done at any MOT garage, or most garages really. it'll be £10 at most, or free if you ask nicely and catch them when they arent busy. all they do is stack a probe (called a lance) into the exhaust and an engine speed (rpm) sensor near the crankshaft pulley or camshaft pulley(s) then read the values on the digital display.
for high CO at idle and /or fast idle and Lambda is too low, the mixture is too rich. This can be caused either by a misfire or by a faulty Lambda sensor. If it's running very rich, the 02 and HC will be higher than normal.
if it has a high Lambda and high 02 (0.5 to 1.5%), the cat could be faulty. Before condemning it make sure its hot enough to work, the Lambda and other sensors are working OK and the exhaust downpipe hasn't got any leaks.
if the vehicle has high HC and ok CO, the vehicle is probably misfiring. Or if the CO is high and the Lambda reading is too low, the mixture is probably too rich and it may also be misfiring.
if the CO is high, the Lambda reading is high and the O2 reading is high (0.5 to 1.5%) the cat could be faulty. Again check out the simple measures above before condemning it.
if the Lambda fails then and its too high the Lambda sensor may be faulty, the mixture may be too weak or there may be a hole in the exhaust downpipe. If Lambda is too low the sensor may be faulty, the mixture may be rich or the vehicle may be misfiring
if the emissions are ok it would suggest the fueling is ok, which means you're losing mpg elsewhere (blocked air filter?)
i think you should get more than 120-130 miles to £20.