[Otruba_843]

Originally Posted by Meeni

Don't be facetious. Failing the emission test and having to buy a new cat is quite expensive. Nothing to be amused when it happens.

If you tell me that the Tee mod prevents the cat from reaching operating temperature, that has the potential to clog it, and fail the emission test later down the road (or not, hence the question).

It seems like every time I see him post on here, its always an obnoxious sarcastic comment. "No question is a stupid question"

[Kernel Kurtz]

Originally Posted by Kolyan2k

Why wouldn't it pass emission... its just a flap, even if you remove cat completely it will still pass. It has nothing to do with passing state inspections. Every car manufacture is trying to make their cars greener

Well OK then.

The flap makes your car a Prius wannabe. I'm surprised they don't highlight it in their advertising.

[GAM]

The flap is closed until 3500rpm. It does open up and leave the left exhaust open on start up and above 3500rpm. So if you put the car on the dyno you won't see anything different above 3500rpm. Unplugging the cable will leave the left exhaust open, more noise, and will also get rid of the rattling sound some of us have an start up. The rattling sound is actually the flap assembly turning to close the valve.
Hope that helps

[Kolyan2k]

And I am not ruling out that tech was wrong. He could've been, but for me it makes more sense to use that flap for warm up and not for noise since noise difference is so minimal. Perhaps Corvettes use it foe noise, they have flaps in both exhaust outlets

[Sam335ix]

Mine has been unplugged for a year now and I am catless. No issues here except you can hear my car from a mile away :-) or :-( for some people.

[Meeni]

Originally Posted by Kolyan2k

Why wouldn't it pass emission... its just a flap, even if you remove cat completely it will still pass. It has nothing to do with passing state inspections. Every car manufacture is trying to make their cars greener

Are you sure you understand the difference between a muffler and a catalytic converter (cat) ? If you remove the cat, you will NOT pass emission test, NOx will be out the window and will fail you (not all states have emission test, though). This is a box that contains chemicals, if it gets abused (overhead, contamination from coolant/oil additive), it gets damaged and needs to be changed for much $$$.

Now it seems the flap has nothing to do with the cat (heating it or not) and that running the cat cold for extended period of time has no effect on it (checked myself since I got ironic answers here... ).

[Beemw335]

OP just jump off a bridge already.

[Beemw335]

Originally Posted by Slow_335i

So I just removed my rear seats and was wondering if anyone has a before and after dyno sheet...

Also will this harm my cats?

LOL

[Dark_Knight_335]

It does nothing besides making your BMW sound obnoxious.

[Kolyan2k]

Originally Posted by Meeni

Are you sure you understand the difference between a muffler and a catalytic converter (cat) ? If you remove the cat, you will NOT pass emission test, NOx will be out the window and will fail you (not all states have emission test, though). This is a box that contains chemicals, if it gets abused (overhead, contamination from coolant/oil additive), it gets damaged and needs to be changed for much $$$.

Now it seems the flap has nothing to do with the cat (heating it or not) and that running the cat cold for extended period of time has no effect on it (checked myself since I got ironic answers here... ).

its actually seems to me that you have no idea what you are talking. Many people remove cat converters for performance benefits (called "test pipe" mod), and I have done so on 2 of my cars. Both passed inspection just fine. I believe only CA has different emission regulations which MIGHT prevent you from doing test pipe on some cars

The way cat converter works is when its cold it simply passes much more toxic crap, and it only works efficiently when its running hot. Sooner its warmed up, better it is for environment, and better it is for BMW because now 335i runs greener.

[CombatNinja]

Originally Posted by Dark_Knight_335

It does nothing besides making your BMW sound obnoxious.

x2

I did this and was so annoyed that I put it back to stock within a day. It is just a loud, grumbly noise away from every freaking stoplight.

[Dark_Knight_335]

Originally Posted by CombatNinja

x2

I did this and was so annoyed that I put it back to stock within a day. It is just a loud, grumbly noise away from every freaking stoplight.

I did the same thing Ninja
Should have followed up with a "ask me how I know." Haha

[bulldog_yyc]

Originally Posted by Kolyan2k

its actually seems to me that you have no idea what you are talking. Many people remove cat converters for performance benefits (called "test pipe" mod), and I have done so on 2 of my cars. Both passed inspection just fine. I believe only CA has different emission regulations which MIGHT prevent you from doing test pipe on some cars

The way cat converter works is when its cold it simply passes much more toxic crap, and it only works efficiently when its running hot. Sooner its warmed up, better it is for environment, and better it is for BMW because now 335i runs greener.

If you remove the cat and get a tune or some other mechanism (spacer, simulator) to disable or implement false o2 readiness/readings, then you could pass, depending on the test used. Many jurisdictions have a combination of a visual check, o2 readiness check and a tailpipe sniffer when performing the tests.

Your statement that you will still pass if you remove the cat is unfortunately very wrong. You might pass with other modifications and only if they are not doing a visual check and tailpipe sniffer.

Also, cut out the attitude - your description of how a cat works is worse than what a 9th grade chemistry student could describe.

[Kolyan2k]

Originally Posted by bulldog x6

If you remove the cat and get a tune or some other mechanism (spacer, simulator) to disable or implement false o2 readiness/readings, then you could pass, depending on the test used. Many jurisdictions have a combination of a visual check, o2 readiness check and a tailpipe sniffer when performing the tests.

Your statement that you will still pass if you remove the cat is unfortunately very wrong. You might pass with other modifications and only if they are not doing a visual check and tailpipe sniffer.

Also, cut out the attitude - your description of how a cat works is worse than what a 9th grade chemistry student could describe.

no one does visual or sniff tests in MA, both my 95 and 98 Nissans did not have cats and both did not smell and both did not trigger CEL. With S2000 test pipes that are sold also pass all inspections and only trigger CEL in some cases which can be fixed easy. Moreover, state inspections here are done by mechanics for $30 bucks, no one is going to spend time sniffing or looking at your car, thats why inspection computer does all emission tests with OBD and/or probe that goes inside your exhaust pipe. If probe detects unacceptable emission levels, you dont pass inspection.

and here is HOW CAT WORKS not from a 9 year old. Although its a forum, not a fucking college chemistry exam

http://auto.howstuffworks.com/catalytic-converter.htm

"The catalytic converter does a great job at reducing the pollution, but it can still be improved substantially. One of its biggest shortcomings is that it only works at a fairly high temperature. When you start your car cold, the catalytic converter does almost nothing to reduce the pollution in your exhaust.
One simple solution to this problem is to move the catalytic converter closer to the engine. This means that hotter exhaust gases reach the converter and it heats up faster, but this may also reduce the life of the converter by exposing it to extremely high temperatures. Most carmakers position the converter under the front passenger seat, far enough from the engine to keep the temperature down to levels that will not harm it.
Preheating the catalytic converter is a good way to reduce emissions. The easiest way to preheat the converter is to use electric resistance heaters. Unfortunately, the 12-volt electrical systems on most cars don't provide enough energy or power to heat the catalytic converter fast enough. Most people would not wait several minutes for the catalytic converter to heat up before starting their car. Hybrid cars that have big, high-voltage battery packs can provide enough power to heat up the catalytic converter very quickly."

[melloww22]

WTH OP two pages of feces... And , by I replying, I am helping it grow...

I hoped this was not a real post, but it is... No wonder the other forum continues their shit growth...

[bulldog_yyc]

Originally Posted by Kolyan2k

no one does visual or sniff tests in MA, both my 95 and 98 Nissans did not have cats and both did not smell and both did not trigger CEL. With S2000 test pipes that are sold also pass all inspections and only trigger CEL in some cases which can be fixed easy. Moreover, state inspections here are done by mechanics for $30 bucks, no one is going to spend time sniffing or looking at your car, thats why inspection computer does all emission tests with OBD and/or probe that goes inside your exhaust pipe. If probe detects unacceptable emission levels, you dont pass inspection.

and here is HOW CAT WORKS not from a 9 year old. Although its a forum, not a fucking college chemistry exam

http://auto.howstuffworks.com/catalytic-converter.htm

"The catalytic converter does a great job at reducing the pollution, but it can still be improved substantially. One of its biggest shortcomings is that it only works at a fairly high temperature. When you start your car cold, the catalytic converter does almost nothing to reduce the pollution in your exhaust.
One simple solution to this problem is to move the catalytic converter closer to the engine. This means that hotter exhaust gases reach the converter and it heats up faster, but this may also reduce the life of the converter by exposing it to extremely high temperatures. Most carmakers position the converter under the front passenger seat, far enough from the engine to keep the temperature down to levels that will not harm it.
Preheating the catalytic converter is a good way to reduce emissions. The easiest way to preheat the converter is to use electric resistance heaters. Unfortunately, the 12-volt electrical systems on most cars don't provide enough energy or power to heat the catalytic converter fast enough. Most people would not wait several minutes for the catalytic converter to heat up before starting their car. Hybrid cars that have big, high-voltage battery packs can provide enough power to heat up the catalytic converter very quickly."

In your small world within MA, you could possibly pass as you describe. But I highly doubt a vehicle with no cats could ever "not smell" - that is a subjective measurement and defined by you. To someone else, it probably smells pretty bad! Also last time I checked, this is E90post not MA_E90post so people from outside MA (to your surprise) do visit this forum

[Chris_506]

Originally Posted by Slow_335i

So I just removed my rear seats and was wondering if anyone has a before and after dyno sheet...

Also will this harm my cats?

Depends on the color of your interior, removing saddle brown rear seats might affect performance and throwing them on top of your cats may damage them and potentially cause life threatning injury..

I had the dyno somewhere but i used the back of the sheet to write my letter to santa..sorry

[Kolyan2k]

Originally Posted by bulldog x6

In your small world within MA, you could possibly pass as you describe. But I highly doubt a vehicle with no cats could ever "not smell" - that is a subjective measurement and defined by you. To someone else, it probably smells pretty bad! Also last time I checked, this is E90post not MA_E90post so people from outside MA (to your surprise) do visit this forum

or perhaps pre-cat is enough to clean the gases. back in the days i never heard of anyone not pass inspection for cat delete on Nissan Maxima.