I have a 1995 import WRX
last time it had mot it had standard exhaust apart from a new backbox and it only just passed CO levels at fast idle.

my results were:-
CO - 0.199% out of 0.200%
HC - 22ppm out of 200ppm
lambda 1.003 out of 0.970 - 1.030

so can anyone tell how my car was running from these firgures ?


recently i put a Cobra sport backbox and DECAT centre but KEEPING the original downpipe.

its also just had a simota airfilter, mobil 10w 40, and oil filter and ngk spark plugs are only 1 year old at 13,000KM covered.

i guess im worried im gonna fail because of the decat centre pipe as the CO only just past last time with the standard cat pipe on, ALBEIT the cat centre had a rattle inside when i took it off recently so it coulda been buggered!!!

any advice ?

 

also just to add
the natural idle test result was

0.280% out of 0.300%

 

bump

can anyone tell me if i will pass MOT with a decat centre and backbox ? 3 " bore

standard downpipe
engine standard.