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E85 / E86 Z4 (2003-2008)
E85 Z4 Roadster, E86 Z4 Coupe, E85 Z4 M Roadster, and E86 Z4 M Coupe talk with our BMW gurus here.

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  #1  
Old 03-04-2013, 03:48 PM
bmwschnell bmwschnell is offline
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Location: Ohio
 
Join Date: Jun 2008
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Mein Auto: Z4M Coupe
Z4M headers

So I know this has been discussed and most people have already figured out how to do it. I have an '07 M coupe. I'd like to get rid of the hefty stock headers. I was thinking about getting some euro headers, but I've been told they no longer are importing them into the country. That being said, I'll probably find another set and modify my secondary cat to accept the rear O2 and EGT sensor, and then get an ESS tune to eliminate any CEL issues.

This is where the problem begins. I think I can probably find a muffler shop capable of welding in the new bungs to the secondary cat, but I also realize you have to extend the sensor cables to reach the new location. I have NO clue how to extend the cables. Is there anywhere you can buy pre-extended O2 cables? If not, are there any places that can do this? Last, if I have to do it myself, how do you do it?

My other option is to buy a set of Mach Schnell or Fabsport headers. These already have places to put all the sensors. The only problem is, I'm not sure if this will set off the CEL. I spoke to ESS, and they said that even after a flash, they can't guarantee the CEL won't come on unless I have the european exhaust setup.
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  #2  
Old 03-05-2013, 02:16 PM
pokeybritches pokeybritches is offline
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Location: Gulf Coast
 
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Mein Auto: 06 Z4MR, 03 Z4 3.0i
If the secondary O2 sensors are installed in your new catless headers, you WILL get a SES light without a tune. You have to relocate them after the other set of cats, because all the secondary O2's do is analyze the functionality of the catalytic converters. By relocating them, you're putting a cat between the primary and secondary O2 sensors, and you don't get a SES light because the ECU sees a difference in output of the O2 sensors. If they are co-located in catless headers, they will both read similarly and the ECU will know you're running catless.

I've heard of others unfolding the extra wire in the harness and finding it to be enough to extend the O2 sensors.

Other tuning companies besides ESS offer flashes that supposedly get rid of the SES light. Active Autowerke, Evolve, etc. I have an Active Autowerke flash on my Z4M and have been happy with it.
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  #3  
Old 03-05-2013, 04:19 PM
bmwschnell bmwschnell is offline
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Mein Auto: Z4M Coupe
Thanks Pokeybritches! What type of setup do you have? Do you have the o2 sensors relocated?

I guess my real question is if anyone knows whether a CEL light will be triggered with a tune from ESS, evolve, active autowerke, etc., if they have all 4 o2 sensors and the EGT sensor in the catless header itself (such as with the fabspeed and macht schnell setups)?

I spoke to ESS and they said they can't guarantee it unless the o2 sensors are relocated behind the cat. Just wondering if anyone has had success doing this setup with a ecu tune.
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  #4  
Old 03-05-2013, 04:49 PM
pokeybritches pokeybritches is offline
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Mein Auto: 06 Z4MR, 03 Z4 3.0i
I'm looking into developing my own simulator as we speak.

Right now the car has a stock exhaust except for the mufflers (Rogue Diablos). Next month I'm installing a G-Power supercharger kit, Supersprint V1 stepped headers, and a Supersprint connecting pipe modified with HJS cats and J-bungs. I'll relocate the O2 sensors and cross my fingers that I don't get a SES light.

The simulator is going to be for my supercharged Z4 3.0i. I have Supersprint headers to install and haven't decided on aftermarket cats yet, or trust many shops to weld everything together correctly and install the extra O2 sensor bungs. There are no secondary cats on my Z4 3.0i. There are little "isms" with these things, like you want the rear of the O2 sensor to be elevated 10 degrees above the probe to avoid having water ruin the sensor. The O2 sensors are able to vent with only the little space between the wire and rubber insulation, but the slightest debris (including water) will cause false readings. I don't live in an area that does a lot of these installs (south Mississippi), and because I'm not 100% confident they will get it right, I'm going out on my own to figure something out. I'll likely have cats welded in just because I care about the environment and don't want a 4-digit ticket, and I'll use my simulator trickery to get around the sensor portion.

But to answer your questions, talk to AA or Evolve. I'm pretty sure you don't need to relocate the O2 sensors and can get the SES light removed with a tune (not ESS apparently). Just know that you will never pass an OBDII-based emissions test, because the car will return "not ready" when plugged up.
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  #5  
Old 03-05-2013, 06:04 PM
bmwschnell bmwschnell is offline
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Location: Ohio
 
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Mein Auto: Z4M Coupe
Thanks! I can understand the not trusting a local muffler shop to do it correctly. I live in the southern ohio, northeastern kentucky, west virginia tri-state. The two options I really have at this time are buying some sort of pre-made s segment with the o2 bungs already built in. It is my understanding that DKF is making exactly this. This would definitely work great with a euro header. The only problem is that I'd have to reroute all the wiring for the o2 sensors, and I don't trust myself with wiring. I've heard people who have this setup and don't even need a tune.

The other option is to just get the fabsport or macht schnell header and keep the stock secondary cat. As long as it doesn't throw a code, I don't have to worry about emissions. We don't have any emissions testing here. When you say it will say "not ready", does that mean that the car's performance will be compromised at all? I don't want it to lose any power.
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  #6  
Old 03-06-2013, 03:02 PM
pokeybritches pokeybritches is offline
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Quote:
Originally Posted by bmwschnell View Post
The other option is to just get the fabsport or macht schnell header and keep the stock secondary cat. As long as it doesn't throw a code, I don't have to worry about emissions. We don't have any emissions testing here. When you say it will say "not ready", does that mean that the car's performance will be compromised at all? I don't want it to lose any power.
You will get a code with either of these headers unless you get a tune. There has to be a cat between the primary and secondary O2 sensors to not get a code. An O2 bung does nothing for you other than give you somewhere to put the extra O2 sensors so they aren't just hanging out. The extra bungs shouldn't be much of a selling point.
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