yanspeed

assumed this was because car was decatted,however upon removal both cats today they both appear intact,with no rattles,

these are the figures from failure yesterday;
CO - %6.4 [legal limit-0.2]
HC - 415 ppm [legal-200 ppm or less]
LAMBDA = 0.81 [legal 0.97 to 1.03.

i know cats dont last forever,dont mind putting a new one on front if it cures problem,however would like to be sure it is the cat at fault.

car runs+boosts fine,just had oil/filter/new plugs/new coil pack,only mods are a filter+backbox,only problem i have is idle can drop off when coming off throttle,likes to stall at junctions before idle catches up+corrects its self then idles fine,i assumed idle control valve could do with a clean ,could i have an air leak somewhere causing my poor emissions?,would a dodgy maf throw me out this far?.

car doesnt smoke at all,been round all boost pipes+they all seem tight+not leaking,no faults showing from ecu

car only failed on emissions,nothing else

speedking

Try reading this thread post #8, and here perhaps.

Plenty of options if you google.

scoobeedoo

iTrader: (1)

I've heard that sometimes a £20 sticking out of the ashtray at test time can help . Not from personal experience of course.

yanspeed

already done all that,the lambda is within limits when i test it,so are all the coil packs,ecu not throwing up any faults,maf seems ok,not giving any of the normal symptoms.
perhaps i should explain that ive been a mechanic for over 22yrs before i joined the coastguards last year,ive come across dodgy mafs/cats etc over the years,however these readings are not what i would expect from the "normal"faults.
not had that much to do on impreza turbos over the years,only run of the mill stuff like headgaskets/t-belts/fitting new turbos/waterpumps etc when i worked in various main dealers.
the turbos only recently been bought to have on stand by to get me into the 999 calls as quickly as possible in all weathers as im on the search+rescue team

DT-SPD

iTrader: (7)

The lambda reading is wrong indicating the engine is running rich, this will be the cause of the cats not working. Once you can get the lambda = 1 I am sure the cats will start to work and bring down the CO and HC

If you are 100% sure there are no intake leaks then I would suggest that the MAF and/or lambda sensor are causing your troubles.

yanspeed

DT-SPD,i have ordered a bosch 3 wire lamda,and a new front cat,once assembled/bedded in will check again to see what the readings are like,then if no better will try another MAF.
cheers for your input.

CSW_Scoobie

Change one thing at a time when you are faulting this sort of problem. I did as the thread below states and it sailed through. The likely hood is you will not need the CAT.

https://www.scoobynet.com/general-te...ns-failed.html

Denmark

iTrader: (2)

Lambdasonde at fault for sure, you Can tell from the lamda value that it's not regulating

/Skassa

yanspeed

subaru technical help thinks its catalytic converter/an air leak or possibly MAF,with it not having OBD it like urinating into the wind.........

they said try cat first if im sure its got no leaks.

old cats off+new ones here so im not refitting the old one due to the chew involved,i will wait for the new o2 sensor to arrive and then try it out

DT-SPD

iTrader: (7)

Sounds like Subaru technical needs some training. The catalyst has no effect on lambda. If lambda is incorrect then the catalyst doesnt work very well hence the high CO and HC.

yanspeed

mot now done,cat brought everything right bar co2 level slightly high,traced a leak to a crack in the original dv plastic body,swopped my spare audi bosch one in and cars emissions passed.
cheers for everyones help,what a nightmare to get it right,,,,lol