can a 1996 sti get thro mot with only the downpipe cat in place? had an mot and the emissions failed (see results below), im lost on how to get this thro the mot, if anybody has advice and infomation i would be most greatful. ta!.....

results

fast idle test
co 3.71%
hc 120ppm
lambda 0.91

second fast idle test
co 4.62%
hc 150ppm
lambda 0.88

natural idle
co 7.18%

failed!!
any ideas how to resolve and get it thro?

 

They only have one cat anyway as far as i know.(downpipe) UK cars had the centre cat and downpipe.

 

where do u live? i have a centre section u can borrow for mot if your arround swansea

 

thats a nice offer but i live in tamworth (midlands)

 

I'd say it's running a very long way wrong. Even without a Cat, you shouldn't be seeing figures that bad. The Lambda should still be in the 0.95-1.05 region, and I've known lots of cars with no cat to be <1% CO. With a working downpipe cat, it should be more like 0.1-0.2%. Get the car checked out by a specialist, sounds like a sensor has gone or something. Could well be something as trivial as the main O2 sensor or the MAF, with luck.

Put it another way, my 02WRX failed it's last emissions due to having one dead sports cat in the donwpipe (had previously passed with the same single sports cat), Lambda was 1.00 (allowable range 0.97-1.03), HC was around 10-20 (allowable up to 200), CO was about 0.5% on fast idle (allowable 0.3% - fail). With standard downpipe and centre cats, it was Lamba 1.00, HC 9, CO 0.12%/0.05% at fast idle/natural idle. I think you might get more tolerant allowances with a 1996 jap import than I did with a 2002 UK car.

If after sorting the engine out it still won't pass, the downpipe cat is dead, change it for another one. An in tune engine should have no problem passing with a healthy standard downpipe cat.