B8 A4 DIY: Catalytic Converter Removal & HFC or Test Pipe Install

**b6Hate4** · 05-12-2015 06:43 PM

Just torch the f**k out of those cat bolts. You wont hurt anything. I got them red hot then just spun them off very easily.

**heffer** · 05-13-2015 01:22 PM

Originally Posted by b6Hate4

Just torch the f**k out of those cat bolts. You wont hurt anything. I got them red hot then just spun them off very easily.

Do you start cranking the bolts while they're still red hot?

**doowopaudi** · 05-25-2015 11:09 AM

Originally Posted by oascom

I was about do do it by myself... Got all the tools, Pb blaster etc... But then I called shop to ask how much they would charge me with tune together and they told me they will do it for 150+tune cost... I said fuck it for 150 it is wort it.

Lucky me! Shop spend 4h to get that shi.. out. All 4 bolts were stuck and corroded. They had to cut all of them and drill.

Still they charge me only 150 like they said before :)

I'm curious. Did you take it to a muffler shop or a EuroTuning Shop. When you say $150 + tune, what tune are you referring to?

Does anyone here see a problem with taking this job to a muffler shop? I would imagine they would charge much less than a eurotuner shop.

Update. It turns out a muffler shop isn't the best choice for this job because the catalytic converter isn't directly underneath the car. I'm gonna take in to a tuning shop.

**Spm58** · 05-28-2015 07:28 AM

Does anyone know if the bolts going from the downpipe to the hfc are screwed in or how they're held in? I snapped one of them and tried getting banging it out but that didn't work, and the shops I asked want to change $100+ to drill it out

**blbroo** · 05-28-2015 07:41 AM

I think they are bolt and nut. I snapped one having a brain lapse on lefty loosey and replaced it with a both and nut I had in my garage.

**Spm58** · 05-28-2015 09:00 AM

Did it just slide/ fall out? Or was it held in there. I'm thinking of picking up more on blaster and just coating it and hammering it if it's supposed to slide out

**blbroo** · 05-28-2015 04:43 PM

I think I had to encourage it out a bit, but not much. Just go under the car and look at the other side of that connection. If you see a bolt head, it's not a stud.

**Jerry1847** · 05-28-2015 06:29 PM

Originally Posted by Spm58

Did it just slide/ fall out? Or was it held in there. I'm thinking of picking up more on blaster and just coating it and hammering it if it's supposed to slide out

I think the bolt/thread is welded to the midpipe. Just get some metal drill bits and drill it out. Replace with a new but/bolt.

**doowopaudi** · 05-30-2015 02:22 PM

On which hole does the oxygen sensor go?

**richardm0025** · 05-30-2015 02:56 PM

Originally Posted by doowopaudi

On which hole does the oxygen sensor go?

two oxy sensors. one in the front and one in the rear.

Also, I doubt that spacer will work to keep cel light from popping up if you don't get a tune. You might get lucky though.

**doowopaudi** · 05-30-2015 02:58 PM

Shoot, I was supposed to buy two?

**goreckless** · 05-30-2015 03:10 PM

Originally Posted by richardm0025

two oxy sensors. one in the front and one in the rear.

Also, I doubt that spacer will work to keep cel light from popping up if you don't get a tune. You might get lucky though.

Huh????

Originally Posted by doowopaudi

Shoot, I was supposed to buy two?

You only need one spacer and it goes in the second one, post cat.

**richardm0025** · 05-30-2015 03:26 PM

Originally Posted by doowopaudi

Shoot, I was supposed to buy two?

Oh, are you asking where does the oxygen sensor SPACER go? That would be the rear. You already have two oxygen sensors on the car. one will connect in front of the HFC and one will attach to the spacer which connects to the rear of the HFC.

**doowopaudi** · 05-30-2015 03:43 PM

Thank You gentlemen yes I meant spacer

**goreckless** · 05-30-2015 04:28 PM

Originally Posted by richardm0025

Oh, are you asking where does the oxygen sensor SPACER go? That would be the rear. You already have two oxygen sensors on the car. one will connect in front of the HFC and one will attach to the spacer which connects to the rear of the HFC.

Oh I see now, my bad. I knew he meant spacer but didn't see he actually wrote sensor.

**richardm0025** · 05-30-2015 04:29 PM

Originally Posted by goreckless

Oh I see now, my bad. I knew he meant spacer but didn't see he actually wrote sensor.

No worries

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**richardm0025** · 05-30-2015 04:32 PM

Originally Posted by doowopaudi

Thank You gentlemen yes I meant spacer

Are you planning on a tune? I have that spacer and before I got a tune a couple months after I installed my hfc. When near Chicago the light would come on and when I was in Indy the light turned off lol. Let me know how it works out with that spacer.

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**doowopaudi** · 05-30-2015 04:39 PM

Originally Posted by goreckless

Oh I see now, my bad. I knew he meant spacer but didn't see he actually wrote sensor.

It was my bad.

Originally Posted by richardm0025

No worries

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Originally Posted by richardm0025

Are you planning on a tune? I have that spacer and before I got a tune a couple months after I installed my hfc. When near Chicago the light would come on and when I was in Indy the light turned off lol. Let me know how it works out with that spacer.

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Yes, I plan on going stage 2 in July, but I plan on installing the HFC in the next week. I'll let you know.

**Shimmy** · 05-31-2015 11:10 AM

so whats the point of installing the spacer when it seems like most people still get a CEL without the stage 2 tune?

**blbroo** · 05-31-2015 03:18 PM

I have only popped a cel once with a spacer in 4 months

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**trackbaron** · 06-03-2015 09:55 AM

Great write up! I'm looking at a primary cat-delete option. What's the difference between a test pipe and a downpipe? Is a test pipe just a catless downpipe? Can't seem to see the difference.

**Spm58** · 06-03-2015 10:37 AM

Test pipe is a hi flow cat with out the cat, so it's just a hollow tube. The down pipe is what it bolts on to. Turbo, hfc, dp, rest of exhaust

**trackbaron** · 06-03-2015 12:44 PM

Originally Posted by Spm58

Test pipe is a hi flow cat with out the cat, so it's just a hollow tube. The down pipe is what it bolts on to. Turbo, hfc, dp, rest of exhaust

Ok thanks for the clarification.

**The Infiltrator** · 06-03-2015 06:49 PM

I have a 90° spacer on my 034 HFC and I've never had a CEL or issue in the four years of having it.

**Shimmy** · 06-03-2015 06:52 PM

Originally Posted by The Infiltrator

I have a 90° spacer on my 034 HFC and I've never had a CEL or issue in the four years of having it.

you also have a tune, no? i guess I'm wondering what the point is of getting the spacer when people are stage 2 anyways.

**The Infiltrator** · 06-03-2015 07:03 PM

Originally Posted by Shimmy

you also have a tune, no? i guess I'm wondering what the point is of getting the spacer when people are stage 2 anyways.

Yeah I've been stage 2 since 2011 and when I installed the HFC back then everyone said to add the spacer so I did. Not sure if you need it now with the new tune but it doesn't hurt to have.

**doowopaudi** · 06-05-2015 09:20 PM

I think I'm gonna attempt this myself. I've called shops nearby and theyre all in the $150-180 range. May as well save that money for more mods right?

How many of you guys who did this yourself wish you would have had a shop do it instead?

**Spm58** · 06-05-2015 09:50 PM

Doowopaudi it's a pain in the Ass. And that's an understatement. Make sure you have extensions for your ratchet and you'll probably want a breaker bar and I also suggest a ratcheting wrench, it works very well. I believe it's a 15 mm

**doowopaudi** · 06-05-2015 10:19 PM

Originally Posted by Spm58

Doowopaudi it's a pain in the Ass. And that's an understatement. Make sure you have extensions for your ratchet and you'll probably want a breaker bar and I also suggest a ratcheting wrench, it works very well. I believe it's a 15 mm

Looks like I'll be taking a trip to Harbor freight for some tool shopping!

**trackbaron** · 06-05-2015 10:48 PM

I was really pumped for this mod cause it's super inexpensive, but now the install has me second guessing. Anyone get a quote on the install from a shop? I'm going to get one tomorrow, hoping to compare it to something.

**The Infiltrator** · 06-06-2015 05:20 AM

Originally Posted by doowopaudi

Looks like I'll be taking a trip to Harbor freight for some tool shopping!

It's not that bad if it's on a lift and you have the right tools.

**boomtime** · 06-06-2015 11:18 AM

Originally Posted by doowopaudi

I think I'm gonna attempt this myself. I've called shops nearby and theyre all in the $150-180 range. May as well save that money for more mods right?

How many of you guys who did this yourself wish you would have had a shop do it instead?

Originally Posted by trackbaron

I was really pumped for this mod cause it's super inexpensive, but now the install has me second guessing. Anyone get a quote on the install from a shop? I'm going to get one tomorrow, hoping to compare it to something.

If your second guessing it then pay the shop $180, its not for a first time mechanic but its also not that hard. The real danger is rounding off the turbo flange nuts or snapping a stud.
If $180 is too expensive then sell your Audi.

Originally Posted by The Infiltrator

It's not that bad if it's on a lift and you have the right tools.

I only work with cars on my buddy's lift, at his shop with 20 years of accumulated tools.
When I was 20 years old I did everything on ramps or jack stands...and complained about having to buy a $5 socket to use once for that job...

**doowopaudi** · 06-06-2015 01:25 PM

Originally Posted by boomtime

If your second guessing it then pay the shop $180, its not for a first time mechanic but its also not that hard. The real danger is rounding off the turbo flange nuts or snapping a stud.
If $180 is too expensive then sell your Audi.

I only work with cars on my buddy's lift, at his shop with 20 years of accumulated tools.
When I was 20 years old I did everything on ramps or jack stands...and complained about having to buy a $5 socket to use once for that job...

You're right, im gonna put it up for sale. Phew!

**S-Liner** · 06-06-2015 01:44 PM

LOL

Nothing on these cars is difficult to R2...all you got to have is the patience, tools, and the desire to learn.

Anyone can disassemble shit, but taking it apart correctly is just as important as putting it back in.

Good luck, dude.

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**Fburg A4** · 06-07-2015 11:07 PM

Originally Posted by doowopaudi

I think I'm gonna attempt this myself. I've called shops nearby and theyre all in the $150-180 range. May as well save that money for more mods right?

How many of you guys who did this yourself wish you would have had a shop do it instead?

Do it man, don't be scared! On the diy scale this ranks pretty meh. But I think it depends on your resources. If you don't have a lot of tools (or experience) you may find yourself having some issues. Then there is the "uh oh" factor if something bad happens. Like somebody mentioned rounding off a bolt, do you have the tools to address that? Given that you are working on exhaust bolts, there is more of a chance of fastener issues than with other tasks. I've probably removed my cat like 10 times by now and never had a problem, but others have had uh oh moments.

But I am in the save your money camp with this task. My suggestion is that if you get a frozen bolt or are unsure what to do, just put things back together and don't force the issue.

**Nastybutler** · 06-08-2015 04:53 PM

Originally Posted by Shimmy

you also have a tune, no? i guess I'm wondering what the point is of getting the spacer when people are stage 2 anyways.

So when I flash it back to stock so it doesn't get TD1'd when I take it into the dealer for service it's not throwing a code.

**doowopaudi** · 06-08-2015 05:11 PM

Originally Posted by Fburg A4

Do it man, don't be scared! On the diy scale this ranks pretty meh. But I think it depends on your resources. If you don't have a lot of tools (or experience) you may find yourself having some issues. Then there is the "uh oh" factor if something bad happens. Like somebody mentioned rounding off a bolt, do you have the tools to address that? Given that you are working on exhaust bolts, there is more of a chance of fastener issues than with other tasks. I've probably removed my cat like 10 times by now and never had a problem, but others have had uh oh moments.

But I am in the save your money camp with this task. My suggestion is that if you get a frozen bolt or are unsure what to do, just put things back together and don't force the issue.

Of course I'm gonna try it. $180 to remove 7 bolts, plus a diy thread??? This is a no brainer !

But yeah, if i get stuck, eveything goes back and I'll happily pay the shop

**Marko S** · 06-09-2015 12:27 PM

Hey guy, I have a question that I couldn't find any answers too.

Im thinking about getting the 034 hfc with the O2 spacer. Was planning on running it on the stock exhaust with no tune. Is this even possible? Everywhere I've read people put the hfc after the tune and thats stage 2 i guess.

**doowopaudi** · 06-09-2015 12:28 PM

Originally Posted by Marko S

Hey guy, I have a question that I couldn't find any answers too.

Im thinking about getting the 034 hfc with the O2 spacer. Was planning on running it on the stock exhaust with no tune. Is this even possible? Everywhere I've read people put the hfc after the tune and thats stage 2 i guess.

Yes it's possible. You'll get like 10-15hp