headers

[mpower03]

ok i am going to be buying ebay headers.. for those of you have have headers installed on your m coupe i have a quick question about the o2 sensors. It is to my understanding that all 4 o2 sensors don't fit in to the bungs. So with that being said, all i have to do is install the pre cat sensors in the post cat bungs, and leave the post cat sensors out. all the post cat sensors do is test for emissions. The pre cats are for the a/f ratio.I will get a ses light by doing that, but i will most likely do a tune.

Correct me if i am wrong.. thanks

[Z4MCJJ]

Will you dyno your car before and after installation of ebay headers just so we can get an idea if these improve engine power output?

[O-cha]

Originally Posted by mpower03

ok i am going to be buying ebay headers.. for those of you have have headers installed on your m coupe i have a quick question about the o2 sensors. It is to my understanding that all 4 o2 sensors don't fit in to the bungs. So with that being said, all i have to do is install the pre cat sensors in the post cat bungs, and leave the post cat sensors out. all the post cat sensors do is test for emissions. The pre cats are for the a/f ratio.I will get a ses light by doing that, but i will most likely do a tune.

Correct me if i am wrong.. thanks

It's not "I will most likely get a tune" its "I will get a tune or lose a ton of power and totally kill my gas mileage."

Don't consider it an option.

But you have the rest right.



If you get ebay headers do yourself a favor and supply OEM gaskets to the shop that installs them. And make sure they aren't idiots and know which direction the gaskets go on, and not to mix up your O2 sensors/plugs, and not to twist the wiring getting them in/out. And test fit them before bolting them in so they know what to cut. And a bunch of other stuff :/

[mpower03]

i have done header installs before. so i will be doing the install myself. and yes i will do a tune, i don't know why i said most likely. and of course i am going to buy oem gaskets and hex nuts the ones that come with it are crap.i am going to label the o2 sensors so that i won't get them mixed up... i read to many threads where idiots mixed up the o2s. Also read one that cracked me up. some guy didn't think he needed the 02 sensors at all so he didn't even install them.. anyway, yes i know not to twist the wires, but what is need to cut, bungs??? i can't imagine anything having to be cut besides that. is it that it doesn't get directly put in the exhaust flow, or is it clearance issues of it hitting something???

[mpower03]

Originally Posted by Z4MCJJ

Will you dyno your car before and after installation of ebay headers just so we can get an idea if these improve engine power output?

m3forum had all you could imagine.. i would like to but i don't think i have the time to go and get the car dynoed.. sorry

[O-cha]

Originally Posted by mpower03

i have done header installs before. so i will be doing the install myself. and yes i will do a tune, i don't know why i said most likely. and of course i am going to buy oem gaskets and hex nuts the ones that come with it are crap.i am going to label the o2 sensors so that i won't get them mixed up... i read to many threads where idiots mixed up the o2s. Also read one that cracked me up. some guy didn't think he needed the 02 sensors at all so he didn't even install them.. anyway, yes i know not to twist the wires, but what is need to cut, bungs??? i can't imagine anything having to be cut besides that. is it that it doesn't get directly put in the exhaust flow, or is it clearance issues of it hitting something???

Ah you're doing it yourself, good. just mock the headers up with two nut each and try putting some o2s in. It's hit or miss, like I said there are variations. Pay close attention to clearance toward the transmission and clearance toward the other header. As well as clearance toward the EGT sensor.


I have a long standing bet that some of the ebay headers are sold by supersprint because you would seriously have to try to mess up what is messed up about them.

[mpower03]

Originally Posted by O-cha

Ah you're doing it yourself, good. just mock the headers up with two nut each and try putting some o2s in.

i don't understand what you are saying...

[The__J__Factor]

I think he might mean get the headers semi in place and held on by a couple bolts and see if the O2 sensors line up with the bungs.
Let us know how is goes.

[mpower03]

Originally Posted by The__J__Factor

I think he might mean get the headers semi in place and held on by a couple bolts and see if the O2 sensors line up with the bungs.
Let us know how is goes.

ok... i read the diy on m3forum, they but the o2 sensors in before they put in the headers... yea i will let you guys know how i end up. ill report back if i run into problems that i can't resolve myself..

[mpower03]

Originally Posted by mpower03

i don't understand what you are saying...

nevermind after i reread what you were saying i get it.

[DirtBag335]

The 02's fit into the ebay headers, mine are all plugged in. It's a tight squeeze but they fit.

[mpower03]

Originally Posted by DirtBag335

The 02's fit into the ebay headers, mine are all plugged in. It's a tight squeeze but they fit.

oh thats good to know. ill see how it goes.

[mpower03]

just thought i would report back... i have the oem headers removed, and test fitted the ebay headers, i will be able to get all 02 sensors and the egt sensor in. I will just have to grind down the rear header post cat bung a little bit to allow a little room for clearance. i now fully understand what the alignment problems are. i have to go to work now, that is why i didn't finish the install, but i will finish tomorrow and ill report back again.

[O-cha]

Originally Posted by mpower03

just thought i would report back... i have the oem headers removed, and test fitted the ebay headers, i will be able to get all 02 sensors and the egt sensor in. I will just have to grind down the rear header post cat bung a little bit to allow a little room for clearance. i now fully understand what the alignment problems are. i have to go to work now, that is why i didn't finish the install, but i will finish tomorrow and ill report back again.

O2 sensors are extremely sensitive to vibration (you would not think it given that they are screwed into the exhaust) So make sure they are not touching the transmission and the one near the EGT is not touching the EGT or egt bung. Close is too close. They aren't cheap to replace and having to take the headers completely off to do so wont make it fun either.

You see what I mean about the flanges fitting now and the thickness? Also I hope you picked up OEM gaskets too.

[mpower03]

i picked up oem gaskets and nuts, yeah the alignment on the fronts is pretty bad but ill get it. the rear slips right on. the sensor near the egt bung and the egt don't touch, there is plenty of room there. it is just the rear headers post cat bung that bothers me. ill just grind it down. it will fit as is, but i don't like it that close to something, i just want that extra clearance. the flanges are actually really thick, i am worried that i might have to buy longer studs tomorrow.

[Burt Reynolds]

thanks for the update...good luck. Be sure to post a sound clip. Also, what section 1 are you running?

[kav]

Take some pictures please.

[mpower03]

today i installed the headers, i got everything on, labeled all of the o2 sensors. I am running in limp mode. the pre cat 02 sensors are in the pre cat bungs, i couldn't get the post car sensor in the rear post cat bung. so i am running no post cat sensors. to my understanding i don't need the post cat sensors to run the car. please need help.

[mpower03]

im not going to mess with it any more so i am just going to take the headers off and put the stock ones back on.

[mpower03]

before i completly give up, ill take the m3forum's advice and switch my pre cat sensors. hopefully that will work..

[O-cha]

I told you you HAVE to have a tune to do this.

With the post cats out you will get an immediate CEL for the sensor heaters being inoperable. Even if you were able to plug them in (I told you you wouldn't) fairly quickly you would get a CEL for catalytic efficiency. (and would lose a good amount of power)

I know I'm a dick a lot of the time, but when I say things I'm not fucking around.

[Haretakis]

O-Cha, I am not contesting you're knowledge, but I am running the headers without software and can tell you I have no problems. I do not have dyno sheets for proof, but I can tell you how I compare before and after next to my nephews tuned 335i. Before the headers, we were nearly dead even. Typically he pull a nose ahead, and rarely I would pull a nose ahead. The day after I picked my car up we did some pulls. This time I pulled at least half a car every time. Sometimes a car length or more (especially if we ran up past 130). This was all with my 115 pound GF in the car while he had no passenger. I definitely didn't lose power, but my gas mileage sucks ass and the car back fires like a motherf*cker. I know this doesn't help the OP directly, but I just want him to know that the car can run without software. Maybe recheck the O2s?