MOT Failure on Emissions

[japcar_junkie]

Just got back from the mot station with a big red fail across the certificate. Can anyone pls give me some ideas on what might be causing this, anything thats known with S15's or Silvias in general.
My CO values came out at 8.5% rather than <0.3% and HC were around 270 ppm. Lamda values also failed at 0.773 which should be between 0.97 - 1.03.

Im hoping its just spark plugs or something just as cheap like the lambda sensor but any info you guys have is appreciated.

 

[S15RKM]

Is it tuned? Is the cat fitted and not just a dummy box in the exhaust?

 

[LuPix_S15]

I'm not very familiar with emission problems but does it smell? Is it over-fuelling?

 

[japcar_junkie]

It's not heavily tuned, just some general modifications - HKS High Power Exhaust (Cat still fitted), 3'' Turbo Downpipe, HKS induction kit, HP Fuel Pump, think thats all the engine mods.
This is the 3rd MOT i've put it through and never had a problem with it before, from what i can remember all the values were well in for previous years.

 

[japcar_junkie]

There's no smells that i've noticed, nothing that stands out as being any different to usual. I've just been out and reved it over a few times to see if theres anything visable coming from the exhaust i.e. excessive black/blue smoke but nothing.

 

[sparks]

lamba sensor is gone

 

[S15RKM]

lamba sensor is gone

Funny you should say that, I changed mine for a universal one and the CO emissions went through the roof, took it to RC for the MOT and they got it thru

 

[sparks]

i had the same problem with my toyota levin failed twice on emissions times was told it was a leaking exhaust so did all the gaskets then told it was my cat changed my cat failed again then changed my lamba sensor and it flew through the test. i recently changed my lamba sensor on my s15 got a genuine nissan lamba sensor from ebay has done wonders for my mpg it might be worth changing it anyways it may save u a few bob on fuel it has for me.http://cgi.ebay.com/ebaymotors/NISS...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories paste this link

 

[japcar_junkie]

Suddenly occured to me last night, i remembered back to the days of my old FTO and when after 1 bad winter the battery died and after a full recharge the car felt and ran like a bag of nails, but after having a new exhaust fitted i was aware that the ecu continualy learns and self manages the fuling. Well this christmas i'v had exactly the same problem with the S15 and only 2 days before my MOT the battery was dead again and back on charge, i even had to jump start it to get it down there. The battery was changed last night (Yes, halfords actually exchanged a faulty battery that was under warrenty) but could this have affected my emmisions values to that extreame figures.

 

[LuPix_S15]

I very much doubt a dodgy battery would affect the emissions... I'm thinking more the lambda sensor based on what others have commented. Seems the most logical place of failure as long as there are no other basic issues like leaking exhaust, failed cat etc!!

 

[japcar_junkie]

What about if the car had only been driven for 5 miles down a straight 'A road' for for 10 mins since the ecu had been reset, the guy even had to jump start the car at the mot center to drive it in so ecu could have also reset again there. Would a ecu that donr virtually no mile, if any at all, cause such dire emissions reading.