I recently read the thread about removing the cat-conv on the wrx and am seriously considering taking off at least one. To anyone thats done it, do you have any advice on how to pass emissions testing? Or should I be able to pass regardless?
I am planning on trying to pass with just one hi-flow cat. Colorado has pretty strict emissions, so it will be interesting. However, I have 3 years before I have to test.
My advice would be to get the car up to full operating temperature before you go to the testing station. Choose a day when there won't be long waiting lines and finally, leave your car running while it's waiting to be tested.
1. I know everyone is going to hate me for saying this, but ever since I installed my turbo back exhaust with just the one cat, ive had a check engine light on. so what? so while doing some other experimentation with boost pressure and fuel mapping, I throw in some 108 octane booster. I reset the computer as part of my procedure and holy s*** the light is off!! And it stays off until i refill the tank! So I get it on the 4 gas analyzer - basically the same that they use to test emissions here in Jersey, and its actually in passing range with the booster on less than a quarter tank of gas. So if you want to try that - go for it.
2. Heating up the car is absolutely right. Drive your ass off on the way there if youre someplace private and can get tested right when you get there. If you have to wait in line, then when you are next to be tested, hold your engine at 2500 - 3000 rpm. Ignore the looks of the people next to you. Your engine needs to be hot to minimize your emissions.
I dont know the exact numbers you need to pass in your state, so I cant garauntee anything, but hey - give it a shot.
If all else fails - talk to performance guys in your area, there are always people willing to pass you for a price...
Just a thought also, I had my Toyota truck before converting to Subaru and it had straight headers to 4" stainless exhaust with a hi-flow muffler. It passed CA smog w/ flying colors on the dyno-checker.... but wait...we also have a visual check as well and NO SEE CAT = NO PASS.
I agree with NJSubieTech about the Pay for Pass system. If its blowing clean, no need to worry about the dreaded global warming.
passing emissions with ZERO cats is possible. (dunno exactly the margin) problem is visual inspection will fail, if your state does that. i know people pass with flying colors on 1 cat. this is based on other turbocharged cars, however. i dunno what the turbocharger does that cleans up the exhaust so much, but it does. maybe heat? I was pissed cuz turbo kits dont have CARB cert and so are deemed illegal. I wanted one for my integra, but got a supercharger instead cuz that was CARB legal. only problem is it BARELY passes smog... to the point where a slightly old O2 sensor made me fail! I see these turbo guys who pass like the engine was stock and it just pisses me off. Damn CA smog Nazi's!
We used to pass emmissions with no cats with the old Celica GT4 turbo AWD's. Not sure why but they passed many times with absolutely zero cats. Pretty amazing considering how rich the stock Toyota mapping was. With one cat it shoud be any problem.