Failed MOT on emissions, need advice please

[Dubstep]

Hi, so my car went for its mot today and failed on its emissions. Ive had the car sorn'd for the past year while ive done some work on it.
here are my Emission results:

Fast Idle:
CO = 1.24 - fail
HC = 759 - fail
Lambda = 0.988 -pass

Second Fast Idle:
CO = 1.17 -fail
HC = 296 -fail
Lambda = 1.146 - fail

Natural Idle:
CO = 1.50 - fail


The car is modded with SS mani, 3" dp, 200 cell cat and jetex exhaust. Ive connected to a VC and no faults are coming up.

How can i reduce these figures?

 

[aragorn]

The figures are higher than you would expect with no cat at all on a healthy engine, so i'd suggest you need to be looking at fuelling/sensors.

Might be lambda or MAF, or a air leak throwing out adaption?

Have a look at the fuel trims with VCDS.

 

[badger5]

ecu can only control its lambda....

 

[Dubstep]

Ok, so ive got a brought some things to try and fix my issue:
Plugs
Fuel filter
Wynns Clean burn

Should i be looking at getting a new lambda sensor (apy so only have 1 sensor)?
Also ive noticed that it might be running rich as the mpg is bad and there is a faint smell of fuel in the engine bay when engine running, would putting the original airbox back on then restrict the amount of air therefore lowering the ratio?

 

[badger5]

do you have vagcom to check lambda readings

 

[Dubstep]

no :-( only a cheap vc to read/wipe codes

 

[AJC]

I've had exactly the same problem with the MOT last week. I'm about to connect up VCDS to check for fault codes but think I might need a new lambda sensor. Any way to check Bill if this needs to be replaced?