Lambda - Failed NCT

V4TYPER

Member
Hi All,

I have V4 Type R 2.1 stroker, 550 injectors.

So I have a 3" turbo back exhaust - no cats. Each year for the test I swap it from the turbo back for a full std wrx system. Pass emission's no problem.

I was sick of swapping systems, so I dropped it into a place that makes exhausts and had a swappable cat made up on flanges for my 3" system. However it was failing on the lambda.

He suggested putting the mid section standard exhaust on from the cat. He removed the standard 2nd cat from the standard system. Still failing on the lamba, reading 1.09 , read 1.06 on a full 3 inch system. No exhaust leaks either.

So either I stick on the std downpipe , hopefully the new system is upto the job and passes before, basically a big waste of money.

Or my actual lamda sensor is gone bad. It has a bosch sensor I think. I looked up genuine sensors and there all in the region of 250-300 sterling. I can't see any bosch sensors listed online. I think I paid in the region of €100 for it 3/4 years ago.

Whats the opinions? Do I need the downpipe cat to pass?

Ideally I would like to get the swappable cat system working, as that was whole point. I was speaking to my mapper, he said he might be able to tweak it as the lamda should be reading 1.00 regardless.
 
Location and quality of cat is key 👍 is it a genuine Subaru cat or some aftermarket 1 and is it right behind the the turbo if not then it’s not going to pass in my opinion .
I swapped a full standard system in sking with a new lamba on a 2.1 type r and it passed no problem .
Sensor only 100-150quid
 
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Downpipe cat in place is probably a must to pass emissions I would say.
 
+1 on this.
AND ,in my own personal opinion, if your lambda sensor is gone bad, a genuine Subaru part is a must...
 
Location and quality of cat is key 👍 is it a genuine Subaru cat or some aftermarket 1 and is it right behind the the turbo if not then it’s not going to pass in my opinion .
I swapped a full standard system in sking with a new lamba on a 2.1 type r and it passed no problem .
Sensor only 100-150quid

Where did you get your sensor? Local MF can get one for 180 but its a hoffer. Would rather a bosch/denso at least if not genuine.
 
If the CAT is is too far away from Turbo it won’t pass, so if to have a bolt in and out cat down where it meets centre section it’s too far away.
 
If the CAT is is too far away from Turbo it won’t pass, so if to have a bolt in and out cat down where it meets centre section it’s too far away.
Would this effect the lambda readings?

It's passing the C02 on low and high idle.
 
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