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      11-10-2017, 10:54 AM   #1
Nordgeist
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Mods that Pass California Emissions??

Hey all, like it says on the tin: any way of knowing which mods will fail or pass California's insane emissions laws?

I'd really love to get a CSL airbox and tune, but my mechanic warned me it probably won't pass a smog test. Same thing with exhaust, headers, anything fun basically. Is there a website that can tell you what will pass or fail?

Anyone have any experience with this?
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      11-10-2017, 11:36 AM   #2
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Technically you cannot modify anything that will affect the emission related function of the car, i.e. catalytic converters. So aftermarket headers are most definitely out, however a few people run the OEM european M3 or Z4M header and cat which will pass and provide slight gains.

Case in point: my car has an aftermarket x-pipe and mufflers (rogue / stromung) - all of which is bolted on AFTER anything SMOG related. It also has an Eventuri intake and tune. I took my car in for SMOG last month and although I passed the OBDII SMOG test, the technician said I failed visual for the modified intake. I swapped in the OEM box(temporarily) and received a pass.

Not all SMOG centers are as stringent as the next and many folks will pay more for a less discerning eye. It is also worth noting this only occurs every two years and some folks simply swap back to OEM for that short period of time.
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      11-10-2017, 02:11 PM   #3
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Ok, so headers I can understand, but specifically, does anyone have any experience with the CSL air box? I'd really like to invest in that, but not if I'm going to be hassled about it down the road.
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      11-11-2017, 06:36 PM   #4
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Dude just mod the car with whatever you want to put on it. There are so many ways to get around the smog emissions testing that I didn't even bother caring and don't care with any of my current cars.
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      11-11-2017, 09:36 PM   #5
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Quote:
Originally Posted by WeekendWarriorz View Post
Dude just mod the car with whatever you want to put on it. There are so many ways to get around the smog emissions testing that I didn't even bother caring and don't care with any of my current cars.
While I agree and my car is nowhere near capable of passing (legitimately), this was not the question.

Any modification that is performance related runs the risk of failing smog for visual. As mentioned, some shops will be more stringent than others in the visual check, but you always have this risk. Mods that will actually alter emissions will obviously carry extra risk of failing the obd2 scan. Our cars should not be sniff tested since the cutoff is 2001 model year, but I've had jokers sniff my 03 acura anyway, so you never know what to expect.

As I see it, there are 4 options:

1.) Don't modify anything performance related and smog with confidence.
2.) Do simple mods and hope you pass the visual inspection.
3.) Do modifications, revert to stock for smog, test, revert back to modifications.
4.) Bypass the smog test.
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      11-11-2017, 09:39 PM   #6
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Quote:
Originally Posted by Nordgeist View Post
Ok, so headers I can understand, but specifically, does anyone have any experience with the CSL air box? I'd really like to invest in that, but not if I'm going to be hassled about it down the road.
You will have a very hard (impossible) time passing visual with a CSL airbox.
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      11-12-2017, 03:31 AM   #7
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Final drive (3.91 or 4.10).

Personally, I would do s-pipe and mufflers. The s-pipe is easy enough to swap back to stock if they fail you.

The carbon intakes require an alpha-n tune, so you'll need to go back and forth with the tune as well. Rumor is that the ECU can only be retuned so many times before you're locked out and it bricks. I've heard of this happening with 3-series cars, but never on the Z4. So... don't take it as fact, but it's something to look into.
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      11-12-2017, 01:39 PM   #8
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Cant we do aftermarket headers if we put Euro Cats to our Zs here in California? I really would like to go that route some time in the future. But I am afraid of California smog too X-X
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      11-12-2017, 11:35 PM   #9
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Legally, no. But you can probably get away with it, and Euro headers + s-pipe should pass the sniffer.
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      11-14-2017, 06:22 PM   #10
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Quote:
Originally Posted by pokeybritches View Post
Final drive (3.91 or 4.10).

Personally, I would do s-pipe and mufflers. The s-pipe is easy enough to swap back to stock if they fail you.

The carbon intakes require an alpha-n tune, so you'll need to go back and forth with the tune as well. Rumor is that the ECU can only be retuned so many times before you're locked out and it bricks. I've heard of this happening with 3-series cars, but never on the Z4. So... don't take it as fact, but it's something to look into.
You can ODB flash the DME as many times as you want, just don't write to the UIF. There is a limit to the UIF writes but I don't think it will brick the DME. Limit is something like 32.

I have dozens of flashes in two different MSV70s. No issues. Z4 by the way but it makes no difference.
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      11-15-2017, 03:16 AM   #11
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Quote:
Originally Posted by rjahl View Post
Quote:
Originally Posted by pokeybritches View Post
Final drive (3.91 or 4.10).

Personally, I would do s-pipe and mufflers. The s-pipe is easy enough to swap back to stock if they fail you.

The carbon intakes require an alpha-n tune, so you'll need to go back and forth with the tune as well. Rumor is that the ECU can only be retuned so many times before you're locked out and it bricks. I've heard of this happening with 3-series cars, but never on the Z4. So... don't take it as fact, but it's something to look into.
You can ODB flash the DME as many times as you want, just don't write to the UIF. There is a limit to the UIF writes but I don't think it will brick the DME. Limit is something like 32.

I have dozens of flashes in two different MSV70s. No issues. Z4 by the way but it makes no difference.
Good to know!
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      11-19-2017, 04:21 PM   #12
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Quote:
Originally Posted by Reborn_ View Post
While I agree and my car is nowhere near capable of passing (legitimately), this was not the question.

Any modification that is performance related runs the risk of failing smog for visual. As mentioned, some shops will be more stringent than others in the visual check, but you always have this risk. Mods that will actually alter emissions will obviously carry extra risk of failing the obd2 scan. Our cars should not be sniff tested since the cutoff is 2001 model year, but I've had jokers sniff my 03 acura anyway, so you never know what to expect.

As I see it, there are 4 options:

1.) Don't modify anything performance related and smog with confidence.
2.) Do simple mods and hope you pass the visual inspection.
3.) Do modifications, revert to stock for smog, test, revert back to modifications.
4.) Bypass the smog test.

You didn't seem to get what I was saying. F the smog test. I'd rather have my catless exhaust and pay the tech $150 to forcefully get my car to pass the OBD2 scan (you can do that and everyone here in SoCal does) Visual inspection is a joke you're never going to get pulled over and asked to pop the hood.
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      11-20-2017, 01:34 PM   #13
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Quote:
Originally Posted by WeekendWarriorz View Post
You didn't seem to get what I was saying. F the smog test. I'd rather have my catless exhaust and pay the tech $150 to forcefully get my car to pass the OBD2 scan (you can do that and everyone here in SoCal does) Visual inspection is a joke you're never going to get pulled over and asked to pop the hood.
This is what I did when I moved out here.
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      01-23-2018, 02:23 PM   #14
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Euro headers and cats are a great mod to avoid Cali smog issues. It's technically not legal but most technicians will pass you because it looks (and is) OEM. The last guy that inspected my car was very thorough and noticed there was supposed to be a cat on the headers. He eventually passed me but he did make me nervous. So in short the euro headers and euro cats are an excellent mod but a good technician can still fail you.
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      01-23-2018, 02:38 PM   #15
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CSL airbox or ANY aftermarket intake will fail you immediately. A tune is a mod that won't fail you as long as it is done properly leaving the car smog ready. A mild cam won't fail you because the inspector can't see it and it prob won't trip the O2 sensors. Dinan hi-flo throttle bodies won't fail you because they are undetectable. All section 2 and muffler exhausts won't fail you because they are behind the cat.
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      01-23-2018, 03:53 PM   #16
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Also, if you swap out just the air filter for a drop in K&N or BMC filter you will not fail. You can also remove that anti-backflow filter thingy above the air filter.
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