Am thinking about changing my stock exhaust to CT on my 91, but ran into a guy yesterday who was pretty frustrated after his 91 just failed smog. Is this an ongoing problem in California?
CT exhaust and CA smog problems
- Thread starter Seizan
- Start date
Wow what a huge mess and to think I just bought this car three weeks ago not knowing anything about these problems. I previously had a Euro MBZ that had a BAR sticker and I thought it was a headache to pass, but in retrospect it was a breeze. So, most of the posts in the above link date back a few years.....Has it gotten worse??
It is not getting any better, becoming harder as our car ages
I never failed smog since purchasing the car in 2011 with a k&n intake with a Taitec catback. I have since installed dc headers, ct charger on low boost, apx catback, and all new oem airbox with oem filter. The uni filter sounds like darth vader. Yet I still have zero issues passing smog. Is everyone failing the tests driving the car for an hour prior to testing?
I've had no problems passing smog in my 95 as long as I get the cats nice and hot. I've been going to a particular smog shop in Walnut Creek who has experience smogging the NSX and knows that the cats need to be nice and hot before testing.
your car is a 91, too? I am always wondering the smog if i installed DC headers.
I am relieved to hear many people are not having problems. Just found out my car has passed last three tests in CA no fails.
Don't fear CT products. They are tried and true for us blue colored tree hugging Californian's.
Also make sure your car is HOT when you smog it. It also helps to go to a shop familiar with the NSX so they don't spend 10 minutes trying to figure out how to check everything, all the while your cats are cooling off...
Headers and exhaust don't contribute much to overall smog numbers. In fact every cat-back exhaust in CA is technically smog legal (that's how muffler shops can make you a custom exhaust and stay in business).
I spoke with a CA CARB guy about why numbers are decreasing and he said that's most likely because when cars of the same year get smogged, CA takes the best performing cars and averages the numbers. Those averaged numbers then become the baseline numbers that everyone else has to meet. Earlier cars are especially strict because most of the owners are getting their cats & O2 sensors replaced for smog, which lead to better performing numbers, which leads to stricter averages, that everyone else now has to meet.
I compared the baseline numbers for a 1991 a few years ago and they are stricter than they were for my 1995.
Basically in order for your car to pass you need an almost perfectly running car with perfect cats (use OEM cell.. don't use any "high flow cats" when taking the test).
I spoke with a CA CARB guy about why numbers are decreasing and he said that's most likely because when cars of the same year get smogged, CA takes the best performing cars and averages the numbers. Those averaged numbers then become the baseline numbers that everyone else has to meet. Earlier cars are especially strict because most of the owners are getting their cats & O2 sensors replaced for smog, which lead to better performing numbers, which leads to stricter averages, that everyone else now has to meet.
I compared the baseline numbers for a 1991 a few years ago and they are stricter than they were for my 1995.
Basically in order for your car to pass you need an almost perfectly running car with perfect cats (use OEM cell.. don't use any "high flow cats" when taking the test).
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When I had my NSX, I had no problem passing smog back in 2012 and 2015. It had a CTSC, CT-E Headers, Exhaust and Intake. Adding just the CT-E Exhaust won't affect the emissions, it is after all a cat-back. If you do fail, it's probably your cats, assuming you car is running well.
