donromani

*Mods - I looked for a DIY forum but did not find one. Please move to the appropriate thread if this belongs elsewhere. Thanks.

AUDI S4 B5 : Removing Stock Down Pipes + “Piggie” DP install tips

Intro: Why I wrote this guide
I recently replaced the stock downpipes (DPs) from my 2000 S4 with the “Piggie” DPs from VAST performance. I have the Bentley install manual but I’ve found that the factory guides leave a lot out and so I try to get a DIY guide online when I can. All I managed to find was the guide from Mike at VAST, which is useful but relatively spartan. This guide represents my experience getting the DPs out and should work for anyone with access to a decent set of tools, a garage, and some jack stands. There may be better guides out there, and please add your own comments if you feel I did something completely wrong or left a step out!

Disclaimer: It’s not my fault
Doing this kind of work is inherently dangerous, even for an experienced mechanic. I managed to follow these steps without being crushed, electrocuted, incinerated, or blown-up. This is no guarantee that you will be as lucky. Use this guide at your own risk. Use your head and your instincts. Have a friend around in case you are injured, etc. If you hurt yourself or damage your car or other property you accept responsibility. You can’t sue me -I have no money anyway, I spent it all on my car.

Overview: Practice your cursing
This is a frustrating, but not exceedingly complex job. I don’t suggest you plow into this with no previous experience, but a little mechanical know-how will take you far in this case. The bulk of the work is getting at the numerous and often concealed bolts in the tight confines around the big s4 engine. You will likely scrape your knuckles and cut your fingers, hands and lower arms. You will curse the Germans that engineered this complicated engine. You will throw tools occasionally. In the end it is do-able, so stick with it and you’ll get there.

PREP:
You can do this without any rare or proprietary Audi tools. Mikes guide (google for “mike01s4's Step by Step Audi S4 Downpipes Removal Instructions”) has a pretty exhaustive list of the tools you will need or which may prove useful. I would only add a can of PB blaster or Liquid Wrench to his list (WD-40 will work too, but not nearly as well) and a shop light with a long extension cord. Make sure you’re on a flat surface and have at least two cat-style jack stands on hand (rated for the vehicle weight, of course).

Ok – Let’s get started

OPENING UP THE ENGINE BAY
1. Keep the car on the ground, pop the hood and remove the plastic engine covers.
2. Remove the 4 bolts holding the Y-pipe to the top of the engine
3. Loosen or remove the two clamps at the connecting hoses on the Y-pipe. You may need to break these and replace them if they are the one-time use clamps. (5 bucks at autozone for 2)
4. Compress the clamp on the accordion pipe at the MAF housing connection and slide it off so that it hangs loosely.
5. Compress the plastic connector on the last y-pipe outlet hose with your fingers and pull it out.
6. You can now carefully wiggle the Y-Pipe with attached accordion hose free. Put to the side where you won’t step on it.
7. Remove the 3 screws securing the Coolant reservoir to the mounting brackets. Unclip the sensor at the bottom of the reservoir. Rest the reservoir in the engine bay where it is out of the way. Be careful not to pull out the hoses or place them under too much tension or torque.
8. Remove the top of the airbox, MAF and panel filter – put these to the side somewhere (you can remove the entire airbox if you wish)
9. Disconnect the 4 O2 sensors at the firewall. There are 3, green, brown, black, on the passengers side (PS) and one, black, on the Drivers Side (DS).
10. Remove the sensor brackets at the firewall on both sides by unfastening the two small silver nuts on each.

THE FIRST FLANGE NUTS!!
1. You should now be able to look down past the firewall to get a look at the heat shield cover on top of the DPs on each side of the car. Your turbos are under there too but you can’t really see them.
2. Remove the small bolts on top of the heat shields. (this is where the socket allens and a long extension will be handy).
3. On the PS you can remove the top Flange nut as well as the EGT sensor. Use some PB blaster and your longest 17mm wrench to get to the flange nut.
4. Be careful with the EGT sensor – it has a long sensor element that protrudes into the DP. Don’t break or bend the element while removing the sensor.
5. The top flange nut on the DS is more recessed, but also accessible if you have a long enough 17mm wrench. Apply PB blaster here if the bolt is stubborn.
6. The flange nuts have a tendency to spin freely after a few rotations with the wrench. You’ll save time if you can get your fingers on them when they reach this point and remove them that way.
7. If you drop a flange nut after removing it from the threaded stud, don’t worry yet - it will probably fall out when you remove the DP.
8. You can take the DPs out without removing the first O2 sensors. You will want to free the O2 sensor wires from any connection or wire bundles in the engine bay and then push the wiring and connector down toward the DP and through the hole in the heatshield for the O2. (this may become easier after you loosen the heatshield from below in subsequent steps)

UNDER CARRIAGE
1. Loosen the lug nuts on the right and left front tires
2. Jack the front of the car up as high as you safely can and support each side with a jack stand at the supports right behind the front wheels on the undercarriage frame. Pull the handbrake and put blocks or something behind the rear wheels first!
3. Remove the lug nuts and front tires.
4. At the rear of the car – remove the 4 bolts on the two connecting sleeve clamps between the DPs and the cat-back exhaust.
5. Loosen the sleeves a bit by twisting them back and forth and then push the sleeve backwards off of the DPs. You can leave just enough of the sleeve on the DPs so they rest there until you’re ready to take them out.
6. Remove the DP support bolts (the one with the spring) and the mounting brackets.
7. Remove the heat shield cover above the drive axles on both sides. There are 3 bolts on each (one is out of view at the top of the shield), the best way to get at them is with the socket allen, several long extensions, and coming in from the wheel well.
8. If you are unable to get at the bolts from the wheel well you will have to probe around with a normal allen wrench, but with enough manual dexterity it can be done this way.
9. Remove the stock or aftermarket sway bar (as well as the transmission stabilizer bar if you have one installed)
10. Remove the second set of O2 sensors from the cats.
NOTE: I removed the tranny support mounts as per the Bentley manual. You might be able to get the DPs out without doing this, but I’m not sure. Mike does not remove the tranny mounts in his guide. If you want to try without removing the mounts skip steps 11 - 15
11. Support the transmission with a small jack or a stack of wood blocks, etc.
12. Remove the 2 bolts on the bottom of the tranny mounts on the undercarriage frame.
13. Push back the heat shielding on the tranny mount as needed to get to the bolt holding the plastic covered mount to its mounting bracket and remove this bolt.
14. Remove the bolts holding the tranny support mounting bracket to the engine.
15. The tranny support mount should now come out as two separate pieces
16. The Bentley guide says to separate the drive axles from the engine – this is not necessary – you can get to the bottom flange nuts without doing this, although the axles are annoying.
17. Loosen the clamp around the base of the DP heatshields – the heat shields can now move around relatively freely.
18. Remove the bottom 3 flange nuts from the DPs on each side.
19. Grab the DP and pull back firmly to slide the flange off of the threaded studs.
20. Push the sleeve clamp at the rear back until you can easily pull the DP free from the sleeve
21. Giggle, twist, whatever – the DP down and out so that the flange safely clears any remaining obstacles. Repeat for the other side.
Installing “Piggies”

Installation is essential the reverse of removal, with a few differences if you are replacing the stock DPs with Piggie pipes from VAST.

1. The second set of O2 sensors will now be located farther down from the stock location. You have to create slack in the wiring to get the added distance. Do this by removing the wiring from the harnesses and clips starting in the engine bay and working your way down the tranny. Once you have them free from these connections you should have enough wire to reach the new positions. You can also splice additional wire as described by Mike in his guide.

2. You can install the DP’s with the first O2 sensors already installed (which may be easier than doing it after the DP is seated). The trick is to get the O2 wiring through the hole in the DP heat shield and then maneuvering the O2 sensor itself through the same hole. If the heats shield is loose enough this should be do-able with some patience and skill (or luck). Once the sensor is through the hole the DP heat shield pretty much falls into place on the DP. Don’t try to force it or you risk damaging the O2 sensor.

NOTE: IF YOU REMOVED THE FLANGE GASKET ALONG WITH THE DPs DO NOT FORGET TO REPLACE THE GASKET BEFORE MOUNTING THE NEW PIPES! IF YOU FORGET THE GASKET YOU WILL HAVE TO DO EVERYTHING OVER AGAIN!

3. Start the car. Let the engine reach normal operating temperature. Keep your eyes on the DPs, especially the front and rear connections. You may smell a noxious odor at first, and even see a little smoke – this is most likely from paint applied to the replacement DPs to give them a better appearance. The smoke should stop after a few minutes, and should never be very thick. Obviously, if you see an actual fire you are in trouble! The paint burning smell may last a few days depending on how often you drive.
Continue to check for leaks, smoke, or reduced performance (stuttering etc.) loud noises over the next few days after install. If you have any problems make sure all of the flange bolts are tightened properly and that the sleeve clamp is situated properly over both the DPs and the rear exhaust. Also make sure you didn’t forget the flange gasket. If you can’t figure out what’s wrong take it to the shop right away.

Well, that’s it. I hope this was a useful resource for you.

ptatohed

Dude, no offense but this write-up is worthless without photos.

DIY: B5 S4 - Removing DP's to make Piggies (For 6spd))