o2 locations on '04GT

timeless2 · Jul 6, 2005

OK, I have the funds for the MAC H pipe finally (o/r).
$130 from brenspeed.com, shipped.

Tonight I crawled under and took a look at the o2 locations, as I have heard that 2004's need extensions on the MIL eliminator plugs. However, when I got under there, I felt one sensor just before the 1st cat and one directly after the 1st cat. There was nothing after the 2nd set of cats on either side.

Are the extensions needed just to reach where MAC relocates the rear o2 sensor?
If so, what good does it do to relocate the o2 sensor to a location where it has to be wired as a dummy? Just seems odd that 04 is the only year this is required.

Is there another mid pipe that has the o2 bungs right where stock does on the 2004?

Please help, as I thought I was completely ready and now I heard about extensions.

stangman · Jul 6, 2005

yup, you need the extenders for an 04. not a clue why the messed with it in 04 though

dsg_gt2004 · Jul 6, 2005

git-it-83 said:
Are the extensions needed just to reach where MAC relocates the rear o2 sensor?
If so, what good does it do to relocate the o2 sensor to a location where it has to be wired as a dummy? Just seems odd that 04 is the only year this is required.

Is there another mid pipe that has the o2 bungs right where stock does on the 2004?

Please help, as I thought I was completely ready and now I heard about extensions.

-yes
-to tell your computer that everything is operating correctly...
-ford likes for us to spend extra money
- i doubt any company will make a special 04 midpipe..that would be too expensive to produce, so no...just make sure you have 2 extenders and 2 mil's for the rear and you'll be ok

comporange04GT · Jul 6, 2005

You might be able to get away without the mil's. I didn't need them on mine and three other '04s I have put balance pipes on didn't need them either.

timeless2 · Jul 7, 2005

comporange04GT said:
You might be able to get away without the mil's. I didn't need them on mine and three other '04s I have put balance pipes on didn't need them either.

What did you do, then, just use the extensions?
Did you use the rear o2's at all?
Did any lights trip?

BooWFO · Jul 7, 2005

Yeap you need extensions. make your own only 4 wires per 02 sensor and put in elimantors too. Heard too much bad stuff about the plug and plays.
My guess is they were doing some roll over testing on 04's before 05's hit the showroom. They tend to do things like that have the last of a certain model have all kinds of small different changes of things the way they want them on the new style. That way if it develops problems it will be before the new model hits the floors.

96WhiteNight · Jul 7, 2005

I have the plug in Mil's and haven't had a problem they have bee on the car for over 2 years

timeless2 · Jul 7, 2005

Does anyone know where the link was to the DIY o/r pipe installation?

I remember seeing it on here, and someone even listed/photo'd every tool they used....

propellerhead · Jul 7, 2005

I have a few pics in my cardomain thing.

mac1009 · Jul 7, 2005

git-it-83 said:
Does anyone know where the link was to the DIY o/r pipe installation?

I remember seeing it on here, and someone even listed/photo'd every tool they used....

http://www.mustangworld.com/ourpics/fcar/hpip1.htm
You'll need the O2 extensions for sure. Not sure about the mils, as I had my rear O2's turned off in my tune.

timeless2 · Jul 7, 2005

mac1009 said:
http://www.mustangworld.com/ourpics/fcar/hpip1.htm
You'll need the O2 extensions for sure. Not sure about the mils, as I had my rear O2's turned off in my tune.

Thanks, mang!

Mustangl3 · Jul 7, 2005

Heres a list of what i needed to put my mac o/r h pipe on:

12" extension, swivel joint, deep 15mm socket, regular 15mm socket(for top nut where mid pipe attaches to the header), 11/16 (i think) for the nuts supplied by mac, wd-40 or pb blaster to loosen up the nuts if they dont come off, i dont know if you need an impact wrench but i used one, vice grips to tighten the studs (or you could just use a 2 nuts to get them in)

The hardest part for me was removing the top nut on the passenger side header. Im not sure if i could have gotten it off without an impact wrench because the swivel joint was at to much of an angle but maybe i was doing it the hard way. I didt even think of taking the o2 sensor out first, maybe that would have helped but im not sure. Plus i had trouble getting the socket completely on the nut, but again there might be an easier way.
After that the install was pretty easy but it took some work to line up the h-pipe with the cat-back. I put red high temp silicone on all my connections to make sure there wasnt any leaks and anti seize of the o2 sensor threads(dont get it on the actual sensor) just in case but maybe that wasnt needed. Oh and i didnt use the flange extestion that mac supplies and i have no leaks. I think someone said its only needed on '99-mid '01 cars.

comporange04GT · Jul 7, 2005

git-it-83 said:
What did you do, then, just use the extensions?
Did you use the rear o2's at all?
Did any lights trip?

I just use the extensions and haven't gotten a light. All of these cars I have started and ran open header/manifold without the O2's even hooked up and haven't gotten a code. For some reason I don't think that the '04s are as sensative to balance pipes as the earlier cars.

timeless2 · Jul 8, 2005

Mustangl3 said:
Heres a list of what i needed to put my mac o/r h pipe on:

12" extension, swivel joint, deep 15mm socket, regular 15mm socket(for top nut where mid pipe attaches to the header), 11/16 (i think) for the nuts supplied by mac, wd-40 or pb blaster to loosen up the nuts if they dont come off, i dont know if you need an impact wrench but i used one, vice grips to tighten the studs (or you could just use a 2 nuts to get them in)

The hardest part for me was removing the top nut on the passenger side header. Im not sure if i could have gotten it off without an impact wrench because the swivel joint was at to much of an angle but maybe i was doing it the hard way. I didt even think of taking the o2 sensor out first, maybe that would have helped but im not sure. Plus i had trouble getting the socket completely on the nut, but again there might be an easier way.
After that the install was pretty easy but it took some work to line up the h-pipe with the cat-back. I put red high temp silicone on all my connections to make sure there wasnt any leaks and anti seize of the o2 sensor threads(dont get it on the actual sensor) just in case but maybe that wasnt needed. Oh and i didnt use the flange extestion that mac supplies and i have no leaks. I think someone said its only needed on '99-mid '01 cars.

Good tips, man!

timeless2 · Jul 8, 2005

comporange04GT said:
I just use the extensions and haven't gotten a light. All of these cars I have started and ran open header/manifold without the O2's even hooked up and haven't gotten a code. For some reason I don't think that the '04s are as sensative to balance pipes as the earlier cars.

Could it be because the rear o2 is right behind the 1st cat, discounting the effect of the rear cats entirely???

96WhiteNight · Jul 8, 2005

The rear cat is measuring the amount of oxygen after the converter and depending on the reading it adjust the air fuel ratio. If you have no cats its gona throw it way outa wack and you will need the mil's. If you buy an after market with cats then you won't need the mil's. Unless the extensions are now being made to do the same thing as the mil's. I dunno and i doubt it

Mustangl3 · Jul 8, 2005

So on '04s the rear o2's affect air/fuel too? I thought the rears were only there for emission purposes.

timeless2 · Jul 8, 2005

96WhiteNight said:
The rear cat is measuring the amount of oxygen after the converter and depending on the reading it adjust the air fuel ratio. If you have no cats its gona throw it way outa wack and you will need the mil's. If you buy an after market with cats then you won't need the mil's. Unless the extensions are now being made to do the same thing as the mil's. I dunno and i doubt it

Dude, there is nothing behind my rear cat except for pipe, flows, and tips. My 2nd set of o2's is just behind the 1st set of cats.

96WhiteNight · Jul 8, 2005

git-it-83 said:
Dude, there is nothing behind my rear cat except for pipe, flows, and tips. My 2nd set of o2's is just behind the 1st set of cats.

Is this your stock pipe or an aftermarket

timeless2 · Jul 8, 2005

96WhiteNight said:
Is this your stock pipe or an aftermarket

My stock pipe on my 2004. Here is the order of objects:

1. stock manifold
2. stock h pipe joint
3. 1st set of o2's
4. 1st set of cats
5. 2nd set of o2's
6. 2nd set of cats
7. stock h to stock catback
8. flows
9. stock tips

o2 locations on '04GT

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