simonds1

Hey guys, I've got a MY00 classic Impreza, and it's just failed it's MOT on emmisions I've changed everything on the exhaust from the turbo back - Ninja sports cat downpipe, Afterburner de-cat centre section, and Hayward & Scott custom backbox. Now I was under the impression that it should pass an MOT like this? Even with the 2nd cat in the centre section removed? Or am I just wrong? If it should have passed......then the question is......what else is wrong? I haven't had it remapped at all with all these exhaust mods, could that be it? My MOT runs out on friday, and I dunno what to do.....other than just stick the original centre section with the cat back on just to make it pass. But if the problem is elsewhere then I guess that won't help.

It failed on the lambda reading and the CO emmisions if that helps?

Cheers for any advice guys

53

iTrader: (41)

Ask your local club for their favourite MOT test station. Sports cats aren't a guarrantee MOT pass and the older they are the more they breakdown.

dunx

iTrader: (3)

Mine's three years old and passes o.k.

Get it nice and hot and ask them to re-test then !

HTH

DunxC

simonds1

Hmmm I'm still convinced it shoulda passed, and that putting the original centre section back on like the garage suggested, isn't gonna make it pass. Looking at a few old posts on here, it seems that the Lambda sensor being faulty could cause the car to fail on emissions? If my lambda sensor was faulty, would it bring my check engine light on? Or not necessarily?

JohnD

iTrader: (5)

Maybe the lambda sensor is ok and is reporting that your air/fuel ratio is wrong? Sort that out and the CO may fall into tolerance. Did the lambda reading indicate rich?
As it's a 2000MY, maybe also check out the MAF sensor.

JohnD

simonds1

Just to update on this......I took the original subaru centre section of the exhaust (with a cat in obviously) to the garage, along with the original backbox aswell......both of those were fitted back on the car......and it failed it's 2nd MOT yesterday on emissions again!! Ggrrr

The car has been checked for fault codes and none are showing up so the guy doesn't think it's any of the sensors or anything. He's convinced it's the exhaust. I trust this guy 110%, he race prepares imprezas & sierra cossies etc, so he knows what he's on about! It would appear that the sports cat in my Ninja downpipe is ****ed I think? That seems to be the only thing that makes sense? He's asked for my original downpipe now aswell, and reckons that will obviously sort it out. Cuz I've always thought an impreza could pass emissions with just 1 cat left in? Does it matter which cat? Because say for arguements sake that my ninja cat is ****ed, then the first time it went through the mot it would have in effect had no cats, because it had the afterburner de-cat centre section on.....so obviously I would expect it to fail. The 2nd time tho, it had the subaru centre section with the cat in.....so it would've had 1 cat. Should it have passed like that? Ah well, will have to wait & see I spoze.

The only thing I can think of......is that on my way to work the other morning.....I drove over a small (well, what I thought was small!) block of wood.....and the ninja downpipe took all of the impact. It hit right on the corner of it as I drove over it like. It cut through all the heat wrap I had on the pipe aswell so I'm wondering if a bit of a sudden impact to the pipe coulda dis-lodged something inside and stopped the cat working properly? I dunno What do you guys think?

SSCJAY

If the car failed with two cats, this would indicate a faulty sensor not a ****ed downpipe.

My car always used to pass with just the centre Cat in.

Doing a fault code check on the ECU will not automatically tell you if the MAF Or lambda is broken.

Also check the plugs.

stigaz

i dont think the centre has a cat ,is it not just a resonater.

simonds1

The centre must have a cat surely? Cuz I thought Imprezas had two, so if one is in the downpipe.....where could the other one be if it's not in the centre section. I agree with you, SSCJAY. I am thinking it's a sensor. Ah well, will just have to wait & see I guess