NCT emissions fail

scooby ed

scooby ed

Active member
ISDC Club Member
hey lads, put the car through the nct this morning and all she failed on thankfuly was emissions, there is a so called sports cat in it but from the readings my jox holds back as much co2, so i wa sthinking would a standard exhaust system reduce them to pass? :ponder2:

the car is a 98 type r running around 370bhp. the readings were on low idle 5.66 (above 0.5% is fail) and on high idle 2.13 (above 0.3% is fail) with lambda of 0.94 (between 0.97 and 1.03 is a pass)

any advice r recommendation much appreciated :subaru:
 
It looks like you're a bit on the rich side first of all, which may cause at least part of the problem?
Once sorted with proper fueling - getting back to lambda 1 (anyway closer to it, within the given limits) - you can check why emission is too high.
So first check if your lambda sensor is fine?

Then think about cat - it happened to me, that sports 100 cel cat in downpipe apparently wasn't efficient enough so I failed on CO emissions - however with not such a big level of CO emission as in your case. But also with lambda at 1 for all the test time.
 
Those readings are very high. I would say Lambda sensor problem.
 
quick thread highjack! do you need a centre cat in to pass an NCT???

actually thats rather on topic! could be a knackered cat??
 
[quote author=goosie208 link=topic=32401.msg371419#msg371419 date=1322598206]
quick thread highjack! do you need a centre cat in to pass an NCT???

actually thats rather on topic! could be a knackered cat??
[/quote]There is no center cat on the japanese impreza its in the down pipe.I would check if its actually a sports cat and not a decat in it,as it will never pass otherwise then look towards lambda and mapping particularly fueling around idle and high idle as indicated in the nct test :subaru:
 
They seem like extraordinarily high readings, even for a decat.. I would be with Andy on this one, you most probably have a lambda or other sensor problem somewhere along the line..
 
[quote author=BazGF8 link=topic=32401.msg371422#msg371422 date=1322600369]
[quote author=goosie208 link=topic=32401.msg371419#msg371419 date=1322598206]
quick thread highjack! do you need a centre cat in to pass an NCT???

actually thats rather on topic! could be a knackered cat??
[/quote]There is no center cat on the japanese impreza its in the down pipe.I would check if its actually a sports cat and not a decat in it,as it will never pass otherwise then look towards lambda and mapping particularly fueling around idle and high idle as indicated in the nct test :subaru:
[/quote]

My type-R has a decat downpipe and centrepipe with Cat (probably from UK version) and it passed last nct test no problem...

As other lads said - I'd start with Lambda - the reading is 0.94 in yours, so its defo fooked ;)
 
[quote author=Codders link=topic=32401.msg371457#msg371457 date=1322618404]

My type-R has a decat downpipe and centrepipe with Cat (probably from UK version) and it passed last nct test no problem...

[/quote]

Classic never came with a CAT in the center section. That must be after market weld in?
 
[quote author=scooby ed link=topic=32401.msg371364#msg371364 date=1322564145]
hey lads, put the car through the nct this morning and all she failed on thankfuly was emissions, there is a so called sports cat in it but from the readings my jox holds back as much co2, so i wa sthinking would a standard exhaust system reduce them to pass? :ponder2:

the car is a 98 type r running around 370bhp. the readings were on low idle 5.66 (above 0.5% is fail) and on high idle 2.13 (above 0.3% is fail) with lambda of 0.94 (between 0.97 and 1.03 is a pass)

any advice r recommendation much appreciated :subaru:
[/quote]

My car failed on a very similar reason. Low idle wasn`t that bad as Yours but high idle is even worst. Lambda is same. I was told by two subaru experts , it`s likely due to the car not being driven for long. dipetane was an option but safer and quicker is to clean throttle body with carburetor cleaner and give a bit of a hard driving. I`ll do this treatment next week ( unfortunately didn`t have time in the last month when car failed test) and will post how it worked. If it doesn`t help - lambda sensor , cat ........ :hammerhead:
 
cheers lads, i ll get te sensors checked and aybe custom up a standard exhaust with the downpipe and centre section cat, ye the car sounds to be running rich when she gets warm and leave her idle it will eventually cut itself out

cheers for the advice lads
 
:653:After a long time of ideas i have my emmisions down and fit for the NCT. :subaru:
With a bit of help from Gordie for a standard centre section and back box and Martin Tracey of Westward Precision Engineering for the ECU, all is set for saturday :multijump:
 
glad to help best of luck with it lad hope it goes well for ya and if not i'll give ya decent money for it for parts :icon_biggrin:,just messing
 
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