Catless DP and MHD Regarding Emissions Question

Marc08EX · 04-12-2023, 11:02 AM

Hi everyone,

I'm really really confused... I've done a lot of research but I couldn't get a definitive answer. Some people say it will pass and some say to put the stock DP back in. I've searched in the AZ BMW group in facebook but no luck there too.

I'm curious as to whether installing a catless DP and flashing my car with MHD will let me pass emissions? I really don't want to install the DP only to find out I won't pass emissions and have to put the stock DP back on. I live in AZ which allows 1 not ready OBD2 readiness indicator to fail. We don't have visual testing

I've read that using MHD to tune the car will only remove the CEL indicator in the dash. But it will create a not ready indicator. I've read some people post what their OBD2 readiness are and I saw some that say NOT READY and INACTIVE. Does emissions only look at the NOT READY ones for failing? Or do they also count the inactive?

I've also read to flash MHD to stage 0 before going to get the car emissioned? Why is this?

Any help or insight would be appreciated. Thank you so much!

Hauteknits · 04-13-2023, 10:53 AM

Also live in AZ here, when I got tested on my 2008 Audi B8 S5 (stock cats w/ catback), they did hook up something to the gas tank as well as put something behind the exhaust tips. I'm not sure if these were fans to j redirect exhaust away, or if they actually captured something but just FYI. I am fully straight piped w/ a custom-modified JB4 BEF, iirc my emissions does say NOT READY/INACTIVE, but I'll check in an hour or 2 and let you know. I'll also hop in INPA and see what it says. Also 9E60B if it makes a difference

Hauteknits · 04-16-2023, 02:49 PM

J hopped in MHD, Evap, O2+Heater and EGR are all marked as INCOMPLETE. I don't think MHD spoofs emissions, not to mention ur car will smell like gas and any competent AZ emissions tester will auto-fail you. Just hot smog honestly

Spooly · 05-12-2023, 05:53 PM

You have 4 basic options:

Swap dp back to stock (time consuming, but guaranteed pass)

Buy quality high flow catted dp that won’t trip CEL (expensive, might still trip CEL)

Use an o2 sim or o2 defouler/spacer (installation is a little annoying, but not too bad, remove after smog)

Pay for a hot smog (expensive, need to know where to go)

04-12-2023, 11:02 AM	#1
Marc08EX Lieutenant 139 Rep 575 Posts Drives: 2011 E82 135i Join Date: Aug 2011 Location: AZ iTrader: (5)	Catless DP and MHD Regarding Emissions Question Hi everyone, I'm really really confused... I've done a lot of research but I couldn't get a definitive answer. Some people say it will pass and some say to put the stock DP back in. I've searched in the AZ BMW group in facebook but no luck there too. I'm curious as to whether installing a catless DP and flashing my car with MHD will let me pass emissions? I really don't want to install the DP only to find out I won't pass emissions and have to put the stock DP back on. I live in AZ which allows 1 not ready OBD2 readiness indicator to fail. We don't have visual testing I've read that using MHD to tune the car will only remove the CEL indicator in the dash. But it will create a not ready indicator. I've read some people post what their OBD2 readiness are and I saw some that say NOT READY and INACTIVE. Does emissions only look at the NOT READY ones for failing? Or do they also count the inactive? I've also read to flash MHD to stage 0 before going to get the car emissioned? Why is this? Any help or insight would be appreciated. Thank you so much! __________________ 2011 135i 6MT \| Alpine White \| Terracotta Boston Leather \| M-Sport \| BMW Performance Exhaust Resonator Delete \| Active Autowerke Signature Exhaust \| BMW Performance Suspension \| Blackline LCI Taillights \| BMW Performance CF Spoiler \| CF Rear Diffuser \| PPK \| E92 M3 FSB \| Matte Black Kidney Grilles \| VMR V710 Jet Anthracite \| Michelin PSS \| BMW SS Pedals
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04-13-2023, 10:53 AM	#2
Hauteknits Private 11 Rep 59 Posts Drives: 335i E93 N55 6MT Join Date: Oct 2022 Location: Arizona iTrader: (0)	Also live in AZ here, when I got tested on my 2008 Audi B8 S5 (stock cats w/ catback), they did hook up something to the gas tank as well as put something behind the exhaust tips. I'm not sure if these were fans to j redirect exhaust away, or if they actually captured something but just FYI. I am fully straight piped w/ a custom-modified JB4 BEF, iirc my emissions does say NOT READY/INACTIVE, but I'll check in an hour or 2 and let you know. I'll also hop in INPA and see what it says. Also 9E60B if it makes a difference
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04-16-2023, 02:49 PM	#3
Hauteknits Private 11 Rep 59 Posts Drives: 335i E93 N55 6MT Join Date: Oct 2022 Location: Arizona iTrader: (0)	J hopped in MHD, Evap, O2+Heater and EGR are all marked as INCOMPLETE. I don't think MHD spoofs emissions, not to mention ur car will smell like gas and any competent AZ emissions tester will auto-fail you. Just hot smog honestly
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05-12-2023, 05:53 PM	#4
Spooly Private First Class 78 Rep 110 Posts Drives: E90 335i M-Sport LCI Join Date: Oct 2018 Location: East Bay Area, CA iTrader: (0)	You have 4 basic options: Swap dp back to stock (time consuming, but guaranteed pass) Buy quality high flow catted dp that won’t trip CEL (expensive, might still trip CEL) Use an o2 sim or o2 defouler/spacer (installation is a little annoying, but not too bad, remove after smog) Pay for a hot smog (expensive, need to know where to go)
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