taylor3173

Hi guys,

Another failure.

My STi has been remapped, I have now found a dyno graph and its running a little over standard power.

It is fitted with a full Perrin exhaust, Perrin downpipe with a 200 cel sports cat.

The car passed the TUV test over here but they use the new OBD port tester and my local Army MOT tester has the old style probe that they whack up the exhaust.

Now, I didn't get the car warm prior to the test as I didnt have time but its readings were as per the printout which are massivly over!

I have an AEM AFR guage fitted and I was wondering if the lambda was faulty which would be a quick fix but I am more concerned that maybe the 200 cel cat isnt working the way it should or maybe it was just cold.....

The previous owner said it sailed through last time on emmisions, 2 months ago.

I am currently searching for an OEM downpipe with the cats and have so far only found a JDM one thats for the 2.0L STi hatch, would this fit and work?

If anyone wants to lend me their downpipe for some cash that would be great...

After thoughts on what I could do to solve this issue.

Cheers

PS yes I used the search but I want to know specifically about the Perrin system.

taylor3173

birchy2010

iTrader: (12)

If the cats were cold you might as well as have a decat fitted. The cats need to be red hot to work but perrins should pass with ease.

taylor3173

Well, with that in mind..... A2 on to A33 autobhan run plus test right after should do the trick whilst on my favoured Aral 102 petrol

BrownPantsRacing

iTrader: (6)

My 06 WRX with 200 cel sports cat just failed it's MOT for the first time ever because Subaru didn't warm the cat up. They drove it down the road, put it back on the machine and it passed just fine!

As said, they need to be warm or they are useless.

Milneragain

My 07 Hawk sti passed it's MOT in March past with a straight pipe, no cats at all.

I took it for a really hard 10-15 min run down some back roads just before the MOT.

Must have done the trick.

BrownPantsRacing

iTrader: (6)

Sorry, maybe in Ireland but that's certainly not possible to pass a genuine MOT here in England with no cat.

ALi-B

iTrader: (1)

YOu can't emmissions test a cool/cold engine+cat (well you can, but it'll show higher emissions )

0.9 CO isn't that far over, HCs being 150 also point to the cat not being "lit" too. IMO, so with some heat it should drop to acceptable levels.

Warm it up and give it a hard blast immediately prior to testing.

Cpt Jack Sparrow

iTrader: (14)

If you have no CATs why take it for a herd run? that purpose of that is to get the CATs up to operating temperature

boosted

Agreed, no O2 must be present, along with no hydrocarbons. A chemically complete burn must be achieved

ALi-B

iTrader: (1)

Actually it does reduce engine emissions in general. Combustion temps get high enough to clean and burn off deposits on the spark plugs, which during idling or low speed driving get fouled, fuel is easier to ignite, engine has less friction, heat soak means air desnity is less, it also burns off and clears out any oil that may get in there (be it worn engine or turbo). Lots of things basically all meaning more complete and cleaner combustion of the fuel. If it did have cats, it would give them a easier job (less HCs = less to convert )

One thing that narks me with MOTs is a tester that leave cars idling for ages to warm up (30mins+). It just causes nothing but problems on cars which are more fickle (Subarus included).

Milneragain

Shouldn't have been possible over here either, the test is done by a Government Agency, & usually no favours shown, but the hard drive must have been enough to get me through the emissions test, the tester himself liked the car, & must have taken it on himself to let the fact that the car had no cats slip through due to the fact it had passed the emissions test.

If the car had failed the emissions test, I wouldn't have had a hope because that test is computer controlled, & the tester would have had to accept what the computer said.

Nobody was more surprised than I was, I had taken the car up expecting it to fail because I hadn't had time to get the exhaust changed .

rb5 stu

Have you ever seen the tests over here, they are ten times harder to pass than the mainland. The examiner must have liked the car. Theres word that the whole of britain is gonna get the same tests as over here soon.

taylor3173

Thanks everyone, this is just what I needed to and wanted to hear.

Having spoken to the testers they did let the car sit to warm up, as said, useless.

I will give it another go in the next few days and I'll see what happens 👍