Making a cat-less, downpiped, M3 legal in NJ

///M3Fresh · 04-06-2021, 02:54 PM

It sounds like NJ inspection is ODB only? If so, you need to fly or have someone at the dealer plug in a scanner and do a check for all readiness monitors. As stated above, if only one of all readiness monitors is in not ready status (should be 2nd/after cat 02's) you will pass.

If they do an inspection and look under the car or have a sniffer you WILL fail. NO way around it. It seems like if you fail, they now have more reason to dig deeper. Which is opposite from my state. (I just have to go back and pass like normal, once the issue is fixed).

So check what exactly they do and dont over think it if its simply a OBD inspection. But like dpaul said, check the cars current readiness monitors. If there is more than one not ready, youll need to address all others other than the secondary 02's prior to taking it for inspection. I dont know if any state can even see or plugs anything to check if ECU had been tinkered with so that shouldnt even be crossing your mind.

WayneM3 · 04-06-2021, 07:34 PM

I am pretty sure that NJ just uses the plug-in OBD reader to check readiness as I used to live there. NY is the same and you can pass with one not ready and my EVAP never goes ready so I have to get all others to work which is tricky for me. I use this code reader and it works great with the one button I/M key to bring it up. It also automatically updates as they go ready. You can just connect it and see right away if you have a tune that turns any monitors off as you will see multiple X's unless the car has not done a drive cycle after deleting codes. If you want to come into NYC I can read it for you but this is a good tool to have.

If the tune is turning off your monitors then you will need another tune that allows them to go ready - even if you swap back the stock exhaust. I can't see how a stock BMW tune will have any adverse effects with the modified exhaust other than not taking advantage of the extra flow which would mean less power. Obviously I would not run a stock tune with any supercharger setup which has different injectors and many other factors.

BLuRRYM3 · 04-15-2021, 02:39 PM

I ran a setup like this for a while. I did a catless, but resonated, x-pipe. I also did the akrapovic delete-R. When I needed to smog, I put the stock x-pipe back in. Worked great. One year I just became too lazy to keep changing the xpipe, so I have my stock one in.

04-06-2021, 02:54 PM	#23
///M3Fresh Lieutenant 258 Rep 564 Posts Drives: E90 M3 Join Date: Jun 2011 Location: Las Vegas iTrader: (1)	It sounds like NJ inspection is ODB only? If so, you need to fly or have someone at the dealer plug in a scanner and do a check for all readiness monitors. As stated above, if only one of all readiness monitors is in not ready status (should be 2nd/after cat 02's) you will pass. If they do an inspection and look under the car or have a sniffer you WILL fail. NO way around it. It seems like if you fail, they now have more reason to dig deeper. Which is opposite from my state. (I just have to go back and pass like normal, once the issue is fixed). So check what exactly they do and dont over think it if its simply a OBD inspection. But like dpaul said, check the cars current readiness monitors. If there is more than one not ready, youll need to address all others other than the secondary 02's prior to taking it for inspection. I dont know if any state can even see or plugs anything to check if ECU had been tinkered with so that shouldnt even be crossing your mind. __________________ 2009 E90 M3 DCT IB Slick Top \| 2017 911 Carrera White 7MT Slick Top \| 2003.5 E46 M3 CB SMG \| 2005 Audi A4 USP Black 6MT
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04-06-2021, 07:34 PM	#24
WayneM3 First Lieutenant 313 Rep 377 Posts Drives: F90M5 Join Date: Apr 2011 Location: New York, NY iTrader: (2)	I am pretty sure that NJ just uses the plug-in OBD reader to check readiness as I used to live there. NY is the same and you can pass with one not ready and my EVAP never goes ready so I have to get all others to work which is tricky for me. I use this code reader and it works great with the one button I/M key to bring it up. It also automatically updates as they go ready. You can just connect it and see right away if you have a tune that turns any monitors off as you will see multiple X's unless the car has not done a drive cycle after deleting codes. If you want to come into NYC I can read it for you but this is a good tool to have. If the tune is turning off your monitors then you will need another tune that allows them to go ready - even if you swap back the stock exhaust. I can't see how a stock BMW tune will have any adverse effects with the modified exhaust other than not taking advantage of the extra flow which would mean less power. Obviously I would not run a stock tune with any supercharger setup which has different injectors and many other factors.
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04-15-2021, 02:39 PM	#25
BLuRRYM3 Private First Class 31 Rep 128 Posts Drives: Jerez Black e92 M3 Join Date: Aug 2015 Location: SoCal iTrader: (0)	I ran a setup like this for a while. I did a catless, but resonated, x-pipe. I also did the akrapovic delete-R. When I needed to smog, I put the stock x-pipe back in. Worked great. One year I just became too lazy to keep changing the xpipe, so I have my stock one in.
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