catless downpipe and emissions

[austinw24]

I live in Texas where they use OBD to determine emissions testing for state inspection. if I were to install a catless downpipe would I auto fail? or would clearing the check engine and a tune evening things out allow it to pass.

In searching I saw something mentioned as a J fitting for the downpipe. would that allow it to pass emissions or is that just to prevent the code?

 

[sx sonic]

You'd fail a sniffer test and visual inspection

If they just check for codes and readiness monitors you could pass by clearing fault codes before you go in for testing, it takes 60-120 miles for the code to show up between clearings.

The J-fitting will keep the code from setting altogether.

Tuning disables the monitors that check the parameters for that fault and keep the code from setting. They will discover the monitor has been disabled and fail you.

 

[jonboys66]

It will not pass by clearing the code right before going in. The readiness monitor wouldn't be ready until you drive the required miles. Then it would just set the check engine light again.
You could use the j fitting. It might or might not work. I have heard it works most of the time.

 

[Blue hedgehog]

It will not pass by clearing the code right before going in. The readiness monitor wouldn't be ready until you drive the required miles. Then it would just set the check engine light again.
You could use the j fitting. It might or might not work. I have heard it works most of the time.

^ this.
Also here in NY anyway, the inspection machine plugs in to the OBD II connector and 1. Verifies there are no codes present and 2. Verifies at least 3 of 5 tests have passed since last code clear. I know o2 sensors are 2 of those tests, the other 3 I don't remember.

 

[ss2000slp]

Also have to keep in mind that they may do a visual inspection. I got my 2000 Camaro to pass with hollow cats and o2 simulators. You could smell the raw exhaust from the back but the computer said everything was good. They looked underneath and saw what looked like cats and gave me the thumbs up.
The J pipe basically moves the o2 sensor away from the exhaust so it won't register a real reading. Subie guys have been doing this for a while, and I've used a similar trick on customers cars that would set a light after installing a "high-flow" cat. Definitely works on quite a few cars, but again, doesn't mean sh*t if they do a visual inspection.

 

[ss2000slp]

In CT you can have one monitor not go, but it can't be the catalyst.

 

[Larrymer]

Just get one with a cat. It's a little more expensive but really nowadays they don't hurt flow very much.

 

[Luv2xlr8]

I thought we were the only ones in Toronto Canada doing this, I think it's just a money grabber for the government. I had problems with my 96 civic because I had converted it to a OBD1 so it couldn't read the OBD2 port showing there was an error.

I've been thinking, could the trifecta fail the emission if I were tuned and put it back to stock tune? Would it notice that its been tampered?

 

[ss2000slp]

Nope. Even with the tune, unless you have the catalyst monitor turned off for a downpipe it will pass. The only issue you may have is if you flash back to stock right before going through emissions the monitors won't have time to set.