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      09-10-2007, 01:53 AM   #1
ricerx1
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M3 Ebay headers fit Z4M

Since it was only 200 dollars I decided to just take a chance and try it. The figment was near perfect, its as good as you can expect it to for aftermarket parts. Alot better then spending 1000 for ss.

I went with longer header studs but afterwards I was thinking about it it wasn't really necessary and I could have just stuck with the stock ones. Could have saved me a lot of time as removing the stock studs and putting on new studs, and then threading the brass self locking header nuts on was a pain in the ass.

The only problem was that the 2nd set of o2 bungs were blocked by the transmission and the front lower control arm, but that wasn't a problem i just capped them off with the included plug. And unplugged the post cat o2 sensors. By doing that it did cause my service engine soon light to come on, I'll probally work on a fix for that later. The only solution i can think of is to put a another pair of o2 bungs after the headers, extend the wires, so i can sill use it to trick the ecu to thinking the o2 heater is there and then running a o2 simulator for the o2 signal wires. But it seems like alot of work for a light because it doesnt feel like the light affected the performance of the car.

The car is definately quicker and louder. I was too eager to put them on so I didnt take any pics during the install. but heres the only trace of it you can see after the install.

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      09-10-2007, 03:24 AM   #2
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dyno???
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      09-10-2007, 02:33 PM   #3
ricerx1
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Quote:
Originally Posted by walbjj View Post
dyno???
I wished I dyno'ed before hand or even tried using my GtechPro but was way to excited and forgot. My friend with a same car should be doing it to his MC soon also so hopefully I'll remember to check the power on his car before and after.

There is no question that there is a gain of some sorts just don't know how much. Sorry couldn't be of much help.
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      09-10-2007, 06:29 PM   #4
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Buttdyno=better.
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      09-13-2007, 11:48 PM   #5
SouthFLBMWMech
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So wait- parts that don't fit and a check engine light dealing with fuel trim are an Improvement??
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      09-14-2007, 01:53 AM   #6
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LOL - yeah, I guess i'll do this mod, AFTER we go to the track next Saturday...
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      09-14-2007, 01:03 PM   #7
ricerx1
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Quote:
Originally Posted by SouthFLBMWMech View Post
So wait- parts that don't fit and a check engine light dealing with fuel trim are an Improvement??
As suprising as it is, yes. The fit was okay not perfect but it still fits. This is the case with most aftermarket parts.

And the check engine light doesn't always cause a change in fuel trim. The post cat o2 sensors are only used to check the conditions of the catalytic converter. They do not cause any change to the fuel maps. Even the pre cat o2 don't cause much change in fuel trims, as they are used for o2 feedback in closed loop driving.

There is going to be a performance increase when exhaust restriction is removed. In this case the headers remove the cat.
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      02-03-2008, 07:24 AM   #8
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Just wondering how these are holding up and what you did about the check engine light?
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      02-03-2008, 11:32 AM   #9
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do you have an exhaust? if your stock how much louder is the car from the outside/inside? does the car stink from the back?? dyno should be similar to the m3s theyve seen 20-25 hps. get a sound clip up
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      02-03-2008, 01:04 PM   #10
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This is my first time seeing this thread, and my knee jerk reaction is: Are you kidding me? You've got to be running rich without the post cat O2 sensor. Any perceived gains could also be due to the fact that you're dumping fuel since post cat reading is 0. Why would they even bother with the sensor if it wasn't adjusting your fuel mix?

My 2cents says you should be immediately concerned with extending the O2 sensor and getting the ECU a proper reading, not just a simulated one.
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      02-03-2008, 01:48 PM   #11
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+1 on extending the post o2 sensor. i am shocked that you are not in limp mode. keep us updated
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      02-04-2008, 09:30 AM   #12
ricerx1
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post cat o2 sensors are only used for emissions. Pre cat o2 sensors are used for fuel trims. The post cat 02 sensors are narrow band sensors to tell the condition/efficicency of the catalytic conversters.
#1 they are narrow band, not good to rely on for adjusting fuel trims.
#2 they are located behind a cat which would make their actual engine a/f off.

The pre cat o2 are wide band sensors.

Dumping fuel does not increase power.........
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      02-04-2008, 10:01 AM   #13
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I can see where you're coming from ricer. I wasn't thinking post cat, I was thinking pre cat for fuel trims. If it is narrow band then makes sense for emissions, but what does its adjust? I can't imagine its only purpose is to throw a cel in the event your cats become clogged. I just feel like it has to be effecting something. Even a pre cat sensor can throw an 0420 and let you know your cat is clogged. What code do you get currently?

My previous car utilized a wide band post cat and yes, it did adjust fuel mixture depending on reading. One way we'd make it read lean was to add a defouler bung to space the sensor a little back, that worked well overall in conjunction with the parts I had on it.

Can I ask how you know for sure the post cats do not adjust AFR? Is this the same in the non-M as well?
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      02-04-2008, 02:27 PM   #14
ricerx1
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Um my innovate wideband does a pretty good job and so does the OBDII Scan Tool.
Post cats o2 is showing heater circuit and lean.

I have tried the Spark Fouler trick but its doesn't seem to work properly. Because they car at idle and cruising will somtimes lean/rich either bank to test the health of the cats.

Post cat o2 sensors exsist for smog for those states that don't use a sniffer. Saves smog stations time. Just plug in a scan tool and instant smog check.
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      02-06-2008, 03:32 PM   #15
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Spark foulers don't work on BMWs. They work great on my VW, but not the bimmer.

You're best just getting a pair of magnaflow cats and extending the O2 sensor wires.
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