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failed mot on emissions

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Old Aug 6, 2007 | 03:36 PM
  #1  
wrxmad's Avatar
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Exclamation failed mot on emissions

as above...please help
i have a 93 wrx with decat exhaust,hks power filter,scooby ecu.
right the car as been running rough for a while..changed plugs ngk 6s.
gapped to 0.6 mm new coil packs fitted ...new lambda.unversial one 3 wire.
into the down pipe ..lambda used to be in headers..ok passed on co2. slow idle.and smoke..didnt pass on second fast idle ... very high hc ...limit is 1200ppm ....came out 3905 ppm wtf its mapped for 97 ron...also used stp fuel system cleaner...on cold startup it idles up to 1500 then starts to drop up and down slightly in between 1500-1000 rpm when warm its better
...but engine still judders slightly.. some mechanic said it sounds like a miss fire????...i have now replaced coilpacks..but still running rough with high hc ...the only fault code that came up was 43 throttle control switch ..but ..
then ecu flashed no faults ...as i was driving ..
any help please as im going to kill my scoob very soon also i dont use it very often...help please
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Old Aug 6, 2007 | 04:58 PM
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From: crawley
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if you dont use it very much mate, then stick some fuel cleaner in it some nice super unleaded and go for a 20 mile blat. This should clear the system out, and also best to do it on the day of the MOT.

I had to do this when i got mine out after sitting in the garage for 6 mths stuck some redex init half a tank of tescos 99 went for a blat to the MOT station and passed with flying colours. Quite surprised actallu as there is no cat on the car at all and its a 98 model :-D.

Good luck matey
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Old Aug 6, 2007 | 07:35 PM
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just a thought i had that fault come up on mine i tried loads of things then i disconnected the battery for a couple of hours and it sorted it you could try that
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Old Aug 6, 2007 | 07:38 PM
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mmm the more i think about it you sound like your in limp mode try disconnecting the battery
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Old Aug 6, 2007 | 09:22 PM
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i also have a wrx 93, and was getting worse readings than that. mine where around 7.9 and 4.2 and 1.6 at full revs. at idle is yours running ok and under the limit? i havent had mine remapped for 97 ron but i always buy 99 fuel to put in it and a shot of redex every couple of months. try changing the oil and oil filter. i was smoking a little but after and oil change new air filter K&N and some sparks plugs, ngk, then it ran really nice but im sure it still wont pass MOT. i kind of took it to a friends MOT station so it passed anyway lol.

i did find out on my import documetns that my car is actually a 92 not a 93 although the regestration documents said 93. so if it is a 92 it only has to pass BET standards which is alot easier. and it also means you dont need a cat at all.
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Old Aug 7, 2007 | 12:11 AM
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Originally Posted by woody1980
i also have a wrx 93, and was getting worse readings than that. mine where around 7.9 and 4.2 and 1.6 at full revs. at idle is yours running ok and under the limit? i havent had mine remapped for 97 ron but i always buy 99 fuel to put in it and a shot of redex every couple of months. try changing the oil and oil filter. i was smoking a little but after and oil change new air filter K&N and some sparks plugs, ngk, then it ran really nice but im sure it still wont pass MOT. i kind of took it to a friends MOT station so it passed anyway lol.

i did find out on my import documetns that my car is actually a 92 not a 93 although the regestration documents said 93. so if it is a 92 it only has to pass BET standards which is alot easier. and it also means you dont need a cat at all.
Pre August 95 imports do not require a cat to pass the MOT emmisions test.

Last edited by robsw; Aug 7, 2007 at 03:53 AM.
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Old Aug 7, 2007 | 12:13 AM
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err.. the fact that you don't have a cat could be something to do with it? Perhaps I've missed something here but that's the obvious thing that's staring you in the face, surely?

As far as the slacker emissions standards go, they were not designed as a get-out for any car older than 1993 to be able to remove its cat(although I had always thought it was 1991 anyway)! They were for smokey old bangers that were a hangover from the 80's and hadn't been factory fitted with cats, to enable them to pass emissions tests. Just because my mate's F-reg 205 GTi is allowed the looser emissions limit (or in fact my old '92 Clio 16v), doesn't mean your 93 (or 92, whatever it is) WRX can be measured against the same limit - AFAIK Imprezas were designed from the ground up with a lambda and cat system like all new 90's cars were.

The days of being able to get cars bodged through the emissions test at friendly garages are long gone.
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Old Aug 7, 2007 | 12:15 AM
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Originally Posted by robsw
Pre september 95 imports do not require a cat to pass the MOT emmisions test.
I'll admit I'm not up on the import loopholes, but are you saying that an imported car doesn't have to follow the same emissions rules as UK cars?
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Old Aug 7, 2007 | 03:52 AM
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That is correct, VOSA only have the UK 'Turbo 2000' model listed in their exhaust analyser database. The import models such as the 'WRX' is not listed. This means that imports registered before 31st July 1995 default to the non-cat test. Imports registered after this cut-off point take the cat test whether they are listed in the database or not. See the link below...

http://www.vosa.gov.uk/vosacorp/repo...01992-2002.pdf

Last edited by robsw; Aug 7, 2007 at 04:49 AM.
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Old Aug 7, 2007 | 10:20 PM
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thanks i hadnt actually researched it thoroughly myself and had only been told by several people that i dont actually require any kind of cat on my car due to import and year.

thinks its time for a big straight out monster exhaust. are flames aload on a emissions test lol.
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