3.0i Header Options

[e39_touring]

I highly recommend doing headers even if you integrate cats as the stock manifold/cat combo is VERY restrictive. Maybe some of the aftermarket manifolds like pacesetter or magnaflow are better. I'm easily getting 10% better MPG's now and quite a bit more power in the mid to upper RPMS.

If I were to integrate cats, I'd use the same headers I got as they fit well and seem very well built. I'd cut the center resonator out and merge the pair of pipes into something like a single 3" cat and then Y it back out to the pair of pipes that goes on to attach to the rear mufflers. It's a straight shot, and you could probably even do it without welding if you don't mind a few extra clamps down there.

But, to answer your question on removing the manifolds, it's not that hard but is tedious. The sway bar and reinforcement plate need to be removed. My car doesn't appear to have ever seen salt, and all nuts/bolts were pretty clean so YMMV.

I don't know if it's required, but I did remove all O2 sensors first. Getting at all the nuts on the head was the tedious part. Some came off in a minute or two while others took 1/2 hour each. Have lots of extensions, wobble extensions, universals, short and deep sockets, etc., handy. They're not that tight and 1/4 ratchet worked for me on most of them even if I had to break it with a box end wrench. I'd say 1/4 to 1/3 of the studs came out with the nut. It's no big deal once the stud's out, just spin two regular nuts (M7) on and back off the bronze lock nut. Then do the same to spin the stud back into the head. I did about a third of them from above and the rest from below. The front manifold will come out first and then the rear. Both have to go out the bottom.

That's all I can think of - good luck!

[trentcdrums]

Originally Posted by e39_touring

I highly recommend doing headers even if you integrate cats as the stock manifold/cat combo is VERY restrictive. Maybe some of the aftermarket manifolds like pacesetter or magnaflow are better. I'm easily getting 10% better MPG's now and quite a bit more power in the mid to upper RPMS.

If I were to integrate cats, I'd use the same headers I got as they fit well and seem very well built. I'd cut the center resonator out and merge the pair of pipes into something like a single 3" cat and then Y it back out to the pair of pipes that goes on to attach to the rear mufflers. It's a straight shot, and you could probably even do it without welding if you don't mind a few extra clamps down there.

But, to answer your question on removing the manifolds, it's not that hard but is tedious. The sway bar and reinforcement plate need to be removed. My car doesn't appear to have ever seen salt, and all nuts/bolts were pretty clean so YMMV.

I don't know if it's required, but I did remove all O2 sensors first. Getting at all the nuts on the head was the tedious part. Some came off in a minute or two while others took 1/2 hour each. Have lots of extensions, wobble extensions, universals, short and deep sockets, etc., handy. They're not that tight and 1/4 ratchet worked for me on most of them even if I had to break it with a box end wrench. I'd say 1/4 to 1/3 of the studs came out with the nut. It's no big deal once the stud's out, just spin two regular nuts (M7) on and back off the bronze lock nut. Then do the same to spin the stud back into the head. I did about a third of them from above and the rest from below. The front manifold will come out first and then the rear. Both have to go out the bottom.

That's all I can think of - good luck!

well that's great information to know. I was kind of hoping that you would tell me it's not worth it but now you have me leaning towards getting headers again. Can you elaborate a little bit on the smell from the car. do you have to always keep the windows rolled up and would it be to the point where my neighbors would be complaining as my car is on idle?

Did you also do everything by yourself or did you get help?

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[trentcdrums]

Also forgot to ask what method you went with to get rid of the check engine light. Does this mean your car will run lean because it doesn't have O2 sensors at the moment? Especially at the rear I see you have them plugged.

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[e39_touring]

Originally Posted by trentcdrums

well that's great information to know. I was kind of hoping that you would tell me it's not worth it but now you have me leaning towards getting headers again. Can you elaborate a little bit on the smell from the car. do you have to always keep the windows rolled up and would it be to the point where my neighbors would be complaining as my car is on idle?

Did you also do everything by yourself or did you get help?

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I imagine the smell would be the same as your old e46. In the e53, you're a little farther away, but if the air is stagnant, I can see it wafting up front or to the car behind you with the windows down. Nobody has ever mentioned to me that my car stinks, but it's rarely stagnant around here.

It's definitely a one-person job, not really room for two.

Regarding the CEL, if you don't have emissions, it's very easy - just flash it with the BMW EU2 calibration (can be done using all BMW tools - basically makes the car euro spec). If you do, it's a little more involved as you have to do a custom tune that turns off the post-cat sensors so it doesn't throw a code for those. In either case, the front sensors are still used and the mixture is correct. The rears are only there to monitor cat efficiency and make very minor fuel trim adjustments if the front sensors are a little lazy.

[lo_jack]

I am definitely doing this the hard way. I got headers that look like they are the same as those pictures until the flange...I don't have any flanges. I am adding cats there, so I chopped down the headers and MIGed on some vbands. Tonight I hope to weld vbands and 02 bungs onto my new 400 cell cats, and then I can put the front section back on and see if it runs. I haven't run it in a long time.

I have been having a deuce of a time getting the new studs in the head with the two nut method. I get them in, but then when you expect to feel the stud bottom in the hole, the second nut will start turning as well so you never really feel them hit--even though they are probably threaded all the way.

The cat on my daily driver is hitting the end of life. It smells awful, and it's a tin can VW with a 2.5. I can't imagine an m54 with no cat. Probably reeks, and should come with a Prop65 warning.

[e39_touring]

Be careful where you put those cats! Make sure there is ample heat shielding above where you integrate your cats (heat rises). Would hate to see you engulf your cabin in smoke from smoldering carpet backing. The flange area looks risky to me.

Re the studs, don't crank them in too tight or you risk cracking the head. Just crank them in until they don't move anymore under modest pressure. Visually gauge the length of engagement and don't force anything.

If your VW is smelling awful with a failing cat, it's running rich, and that's what's probably doing in the cat (cats don't have a service life on a properly calibrated engine). Remember, all a cat does is accelerate a naturally-occurring reaction (oxidation). That smell you refer to is unburned fuel going out the tailpipe. Complete, un-catalyzed combustion hardly smells.

[lo_jack]

Yes, I'll look at the fuel trims again, but mileage has been within expectations. The plugs are old but I can pull those and see how they look. No other codes on the VW besides cat efficiency. Could be a leaky injector or a vacuum leak, I suppose.

I am going to stick extra shielding on the cats between the body and the floorboard. I'll have enough space to add a very short bracket and a bunch of aluminum plate between them and everything else.

The flange area is tight left and right but fine up and down, as far as fitting these small-bodied cats in goes. I have to get them in staggered fore and aft, as they are slightly too wide right next to each other.

Eventually I will put a new resonator in if this all works, but for now its going to be more chop and weld at those flanges on the midpipe. I saved the OEM ones I chopped off the manifolds, just in case I can use them again, but I think my header-cat assemblies will be too long.

[trentcdrums]

Originally Posted by e39_touring

I imagine the smell would be the same as your old e46. In the e53, you're a little farther away, but if the air is stagnant, I can see it wafting up front or to the car behind you with the windows down. Nobody has ever mentioned to me that my car stinks, but it's rarely stagnant around here.



It's definitely a one-person job, not really room for two.



Regarding the CEL, if you don't have emissions, it's very easy - just flash it with the BMW EU2 calibration (can be done using all BMW tools - basically makes the car euro spec). If you do, it's a little more involved as you have to do a custom tune that turns off the post-cat sensors so it doesn't throw a code for those. In either case, the front sensors are still used and the mixture is correct. The rears are only there to monitor cat efficiency and make very minor fuel trim adjustments if the front sensors are a little lazy.

Wonder with the angled adapter of you used them for the post 02 sensors if the light would even come on!!?


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[lo_jack]

Did any of you chase the manifold stud holes? I know they are 7mm and most go in no problem, but the ones that never had a stud before are a bit belligerent.

[trentcdrums]

Originally Posted by lo_jack

Did any of you chase the manifold stud holes? I know they are 7mm and most go in no problem, but the ones that never had a stud before are a bit belligerent.

Not understanding what you're referring to when you say the ones none had a stud in? Should they all have studs in them when you're removing them?

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