Plug anti-fouler O2 sensor mod seems to be working so far.

Nick Gustas · 01-24-2006, 08:11 AM

Last friday my bank 2 ignition amp decided to turn off for a bit, while under full boost in 6th.

The excess fuel from non firing cylinders 4,5,6 melted my bank 2 cat, and blew quite a bit of it out the back. Caused quite the spray of orange chunks in the rearview, and a flashing CE light. I immediately thought I had blown my engine with the power loss and orange spray out the back..

Soo, after "fixing" the amp by cleaning the contacts, car ran fine, but I had a DTC for bank 2 warmup cat efficiency. Since the exhaust didn't smell, I figured some of the cat must be left..

I pulled the cat for inspection, and found this:

Frothy!

I knocked off most of the chunks, and opened the channels as best I could. I did a little more work after these pics. Looks good when held up to a light.

I'll deal with the cat in the spring.

For the "mod", I used the 42009 non fouler, and drilled it out using a lathe and a 19/32" drill. I tried a 5/8" as the archives said, and it was too big, fouler threads broke off.

Came out to this size:

Diameter of sensor:

Sensor in non fouler:

Since the walls of the non fouler are so thin after drilling, I brazed the non-foulers together, figured it might help keep it from cracking off.

This morning I went through the DB047 cat check that was failing after the "incident" and setting the B2 cat efficiency DTC.

Passed!:

It even passes faster than my "good" cat on B1.

We shall see how this works out long term, so far so good.

lemieux@curbside · 01-24-2006, 08:20 AM

Nick Gustas · 01-24-2006, 08:24 AM

exhaust.

I was going to gut it, but it cleaned up so easily and seemed to be working at least a little, I figured I'd give it another chance

mbox · 01-24-2006, 08:26 AM

Chaddy · 01-24-2006, 08:28 AM

PSmalls::DoggieStyle · 01-24-2006, 08:29 AM

Nick Gustas · 01-24-2006, 08:35 AM

dscottjr · 01-24-2006, 08:35 AM

Nick Gustas · 01-24-2006, 08:38 AM

Though the ceramic makes it really easy to scrape off melted parts. Still surprising to see ceramic melt like that.

Nick Gustas · 01-24-2006, 08:40 AM

Might be better off ordering online, I saw a few on EBAY/Froogle.

01-24-2006, 08:11 AM	#1
Nick Gustas Senior Member Account #: 3094 Join Date: Mar 2000 Posts: 7,470	Plug anti-fouler O2 sensor mod seems to be working so far. Last friday my bank 2 ignition amp decided to turn off for a bit, while under full boost in 6th. The excess fuel from non firing cylinders 4,5,6 melted my bank 2 cat, and blew quite a bit of it out the back. Caused quite the spray of orange chunks in the rearview, and a flashing CE light. I immediately thought I had blown my engine with the power loss and orange spray out the back.. Soo, after "fixing" the amp by cleaning the contacts, car ran fine, but I had a DTC for bank 2 warmup cat efficiency. Since the exhaust didn't smell, I figured some of the cat must be left.. I pulled the cat for inspection, and found this: Frothy! I knocked off most of the chunks, and opened the channels as best I could. I did a little more work after these pics. Looks good when held up to a light. I'll deal with the cat in the spring. For the "mod", I used the 42009 non fouler, and drilled it out using a lathe and a 19/32" drill. I tried a 5/8" as the archives said, and it was too big, fouler threads broke off. Came out to this size: Diameter of sensor: Sensor in non fouler: Since the walls of the non fouler are so thin after drilling, I brazed the non-foulers together, figured it might help keep it from cracking off. This morning I went through the DB047 cat check that was failing after the "incident" and setting the B2 cat efficiency DTC. Passed!: It even passes faster than my "good" cat on B1. We shall see how this works out long term, so far so good.

01-24-2006, 08:20 AM	#2
lemieux@curbside AudiWorld Super User Account #: 47312 Join Date: Dec 2002 Posts: 17,783	so u used 2 per side (2x HELP 42009) ? oh and just gut that cat all the way ;) __________________ ************************************************ ************************************* "it's a B5 S4 ,it may break down, but its far enough ahead, by the time its fixed, you still haven't caught up." -best line i've heard ;) AUDI B5 S4 detail info (pdf file) that everyone should read and have saved on his computer AUDI B5 RS4 study guide detail info (pdf file) FATS database VAG-COM LOCATOR ASP Hands down the "BESTEST" tuner out there.

01-24-2006, 08:24 AM	#3
Nick Gustas Senior Member Account #: 3094 Join Date: Mar 2000 Posts: 7,470	Yep, drill one out, leave the other alone, stack them, sensor goes in drilled one, non drilled in. exhaust. I was going to gut it, but it cleaned up so easily and seemed to be working at least a little, I figured I'd give it another chance

01-24-2006, 08:26 AM	#4
mbox Junior Member Account #: 86816 Join Date: Jan 2005 Posts: 2,725	glad it worked for ya. Enjoy!

01-24-2006, 08:28 AM	#5
Chaddy Junior Member Account #: 76469 Join Date: Jun 2004 Posts: 1,763	Sheesh. Didn't know the substrate would melt so readily! __________________

01-24-2006, 08:29 AM	#6
PSmalls::DoggieStyle Elder Member Account #: 69223 Join Date: Jan 2004 Posts: 30,285	Heh, nice work Beavis.

01-24-2006, 08:35 AM	#7
Nick Gustas Senior Member Account #: 3094 Join Date: Mar 2000 Posts: 7,470	I'm glad someone finally found something that works, and just in time for me :)

01-24-2006, 08:35 AM	#8
dscottjr Member Account #: 42392 Join Date: Sep 2002 Posts: 14,595	are 19/32 bits readily available? __________________ 00 S4, Euro spider hose mod!! 04 allroad, needs rs6 intercoolers, k04s and a cargo box...

01-24-2006, 08:38 AM	#9
Nick Gustas Senior Member Account #: 3094 Join Date: Mar 2000 Posts: 7,470	Me either! I think metal matrix cats might do a better job of spreading localized heat. Though the ceramic makes it really easy to scrape off melted parts. Still surprising to see ceramic melt like that.

01-24-2006, 08:40 AM	#10
Nick Gustas Senior Member Account #: 3094 Join Date: Mar 2000 Posts: 7,470	uhhhh, maybe at a hardware store? I know they are right next to the lathe :P Might be better off ordering online, I saw a few on EBAY/Froogle.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode


Discussion Forums:	Advanced Search