emissions and wastegate issue

[Winglessftw]

so i took my 06 wrx in for its emissions test today, and failed with flying colors. its a stock motor with a turboback exhaust and a tune, nothin too outlandish. i had issues with passing emissions 2 years ago as well, ended up welding in a new cat and eliminated boost. where im really struggling is with my NOx levels. the hc's were just barely over limit and i think a fuel additive will take care of that, but the NOx was 5.2 with a max cap of 1.5....so i was almost 3X over the limit. the shop that did the tune on the car 2 years ago somehow disabled the turbo and i was curious how they did it. is there a way to pull the vacuum lines and keep any boost from reaching the cylinders, if only for a few miles to the test and back? im not extremely good at DIY but id like to at least give it a shot, i dont have the money to buy another cat and weld it in.

[MainFrame]

You can run a vacuum line from the compressor outlet straight to the wastegate.. or you can zero out your WGDC in your map. Either way will make you run spring pressure, probably around 5psi.

[Heide264]

There are several people on this board that have pretty good luck passing a sniffer test. Maybe it's your tune? Hopefully some others can pitch in their thoughts.

Mainframe hit the nail on the head - pretty easy to disable any boost over waste gate pressure. I'm not sure that it will help your issue though. I could be wrong - not too familiar with sniffer emission testing.

[Anub1s]

Is the cat still in the exhaust? Could be that it has gone bad.

A poor tune will also not be great for emissions.

[Winglessftw]

Is the cat still in the exhaust? Could be that it has gone bad.

A poor tune will also not be great for emissions.

the tune is quite good, actually. had it redone last year. for whatever reason the turbo is blowing out the cats, which is why it was replaced 2 years ago. apparently its happened again which is unacceptable, i cant reweld a damn cat every 2 years.

[Anub1s]

the tune is quite good, actually. had it redone last year. for whatever reason the turbo is blowing out the cats, which is why it was replaced 2 years ago. apparently its happened again which is unacceptable, i cant reweld a damn cat every 2 years.

That's kind of the problem, though. The turbo isn't going to just "blow out" your cat, they're ruined either by normal operation over a LONG period of time, or a tune that is running pig rich or with not enough timing that is allowing unspent fuel through the exhaust, which then burns inside of the cat, thereby ruining the catalyst. The catalyst could also be ruined by engine oil or coolant in the exhaust system as well. But, unless you've noticed oil levels dropping faster than normal, or a lot of coolant loss, that is likely not the problem.

I suspect a bad tune, or a poor quality catalytic converter was put in last time.

[Heide264]

Agreed with Cody 100% after hearing you have gone through cats quickly.

That's essentially how anti lag systems work... Cut ignition or add a ton of fuel into the exhaust... Then blow it up. Fun if you aren't a catalyst or a turbo turbine.

It's very easy to do from a tuning perspective due to making an overly conservative tune. One of the reasons I went catless. I did not trust myself to preserve a catalyst for long when playing with my tune.