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-   -   euro headers no cats... (http://www.m3forum.net/m3forum/showthread.php?t=298149)

achtungM3 Fri, Dec-11-2009 01:56:37 AM

euro headers no cats...
 
i just installed euro headers with oem section 1 and stebro muffler. wow! crazy loud. i am for sure going to put a resonated section 1 in a some point.
my question is, i took it out for a test drive and it is kind of lurchy and hit and miss. kind of like catching on all cylinders and then not firing on all cylinders. of course the ses light came on. is the computer relearning since i dont have the post cat sensors or the egt sensor hooked up?
thanks...

uniqueM3 Fri, Dec-11-2009 02:56:57 AM

You need to get software of course. Cross ur fingers and hope that fixes the problem cause it sure didn't for me. I installed the supersprint stepped headers with the oversized section 1 with no cats. SES light came on and felt what ur feeling. Took the car to get the software done and ses light still came back on. Got a obd readers and I have a missfire in 3 cylinders and a vaccume leak. Changed the spark plugs and coils and problem still there. Hopefully your ///M3 doesn't go through what mine is going through. Goodluck

EricSMG Fri, Dec-11-2009 03:55:49 PM

I drove my car like that for a couple weeks (no software) and it ran great. More power than stock, for sure, but not super smooth. Once I got software, there was even more power and it pulled smooth all the way.

MEM3 Sat, Dec-12-2009 05:33:04 AM

i think you guys switched your 02 sensors when your headers

achtungM3 Sat, Dec-12-2009 05:45:49 AM

i think so too. i drove the car again tonight after work and same results. i am trying to find info on which two sensors i should leave in and which header they need to be in.

Makavelim3 Sat, Dec-12-2009 09:14:21 AM

So basically you only changed the Headers & Rear exhuast.

I have a euro 2003.6 build M3 (Euro Headers), the car was never noisy with stock exhuast. so in that order you did not get any more noise from your euro headers. It must be the Exhaust only.

I personally don't see much diffrence between stock US spec M3 Vs. Euro Spec M3. I always pull with my friends M3 (US Spec) and the diffrences are minimul.

achtungM3 Sat, Dec-12-2009 02:23:43 PM

it's not louder because of the headers, it is much louder because i have no cat's now. the amount of exhaust gas pushing out of the tailpipes is much greater than before i pulled the cats.

Jumbosock Sat, Dec-12-2009 10:59:18 PM

I'm not sure how the car acts without the EGT sensor in place but at least check to make sure you didn't cross the O2 sensors. This is REALLY easy to do even if you're careful so double check that! One thing I learned is that the position of the header collection pipe is aften times opposite of US OEM. Meaning the rear header collection pipe is closer to the driver in the Euro version while the FRONT header collection pipe is closer to the driver in the US version.

hogger453 Sun, Dec-13-2009 12:06:57 AM

For future ref. Iv'e done four header jobs on the M3.

Number it like this:
#1 front bank
#2 rear bank
#3 front mate
#4 rear mate

The evens and odds always stay together. Works for me

If you keep driving the way you are you're going to burn up your exhaust valves.

Cats are crucial. The ECU is not going to learn the car the way it is. The peramitters are just not there. If your going to run it without cats get software ASAP.

EricSMG Sun, Dec-13-2009 04:23:38 PM

Quote:

Originally Posted by achtungM3 (Post 4420313)
i think so too. i drove the car again tonight after work and same results. i am trying to find info on which two sensors i should leave in and which header they need to be in.

Hmmm.... you'll need to search (or ask someone to post up) for the picture of the 02 routing under the hood and go from there. I remember it was a bit confusing to keep track of them.

That said, my headers have a spot for all 4 02s AND an EGT port... so I didn't actually remove/alter anything. Car ran good. Euro headers only have 2 02 bungs as the rears are meant to be installed into the Euro section 1 (after the cats.) I'm not sure about the EGT either. You might need to get a couple bungs welded into your stock sec 1 and reinstall your rear 02s and then get software...... because I think most software requires all 4 O2s..... I know mine does.


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