Mounting O2 Sensor

[Pat]

Trying to figure where to mount my O2 sensor and then routing the wiring. My exhaust collector goes right into my muffler so I think that if I mount it right at the slip connection it would still be reading basically that one bank. Should I mount it further down on the actual muffler?

 

[Jean-Marc]

Pat, this is the position on my car

 

[Tom]

Hey Pat,
I have over 10k miles on this setup and has worked as it should. Couple things to keep in mind. If your bundle of snakes were made for carb use and not EFI, it may have too many leak points so the O2 sensor will not sample accurately and you'll run into tuning challenges. The Left side arrow shows the EFI O2 sensor, the Right side was my choice to add a stand alone sensor and gauge to compare against what the EFI is seeing, or if ever needed, real-time troubleshooting if you experience a drivability issue on the road. The circled area is the 'double-slip joint'. Many don't know about this type of joint and how well it seals the header-collector interface. The V-band clamp after the collector also seals extremely well, with the additional plus of being able to clock your pipes for alignment, or to easily swap mufflers/megaphones. Several guys will run into EFI issues because the O2 sensor cannot pick up an accurate oxygen reading so it's very important that your exhaust system has zero leaks. Last thing...you only need one sensor on either side to sample both cyl banks.

 

[Pat]

Hey Pat,
I have over 10k miles on this setup and has worked as it should. Couple things to keep in mind. If your bundle of snakes were made for carb use and not EFI, it may have too many leak points so the O2 sensor will not sample accurately and you'll run into tuning challenges. The Left side arrow shows the EFI O2 sensor, the Right side was my choice to add a stand alone sensor and gauge to compare against what the EFI is seeing, or if ever needed, real-time troubleshooting if you experience a drivability issue on the road. The circled area is the 'double-slip joint'. Many don't know about this type of joint and how well it seals the header-collector interface. The V-band clamp after the collector also seals extremely well, with the additional plus of being able to clock your pipes for alignment, or to easily swap mufflers/megaphones. Several guys will run into EFI issues because the O2 sensor cannot pick up an accurate oxygen reading so it's very important that your exhaust system has zero leaks. Last thing...you only need one sensor on either side to sample both cyl banks.
View attachment 150298

Thanks for the picture. So reading from the collector is good to go? I was worried it would basically just be reading that one bank and not all four from the right side. My headers have the double slip joint and I added copper anti-seize so it should be sealed up tight from any air leaks.

 

[Tom]

Pat, if you are running a crossover exhaust, one O2 should suffice, since you are sampling from 2 cyls per bank.

 

[Bill Kearley]

Borla /Holley has had no issues

 

[Tom]

Same here. Good equipment and setup = success!

 

[Paul Proefrock]

@Cobrajet

Hey Pat,
I have over 10k miles on this setup and has worked as it should. Couple things to keep in mind. If your bundle of snakes were made for carb use and not EFI, it may have too many leak points so the O2 sensor will not sample accurately and you'll run into tuning challenges. The Left side arrow shows the EFI O2 sensor, the Right side was my choice to add a stand alone sensor and gauge to compare against what the EFI is seeing, or if ever needed, real-time troubleshooting if you experience a drivability issue on the road. The circled area is the 'double-slip joint'. Many don't know about this type of joint and how well it seals the header-collector interface. The V-band clamp after the collector also seals extremely well, with the additional plus of being able to clock your pipes for alignment, or to easily swap mufflers/megaphones. Several guys will run into EFI issues because the O2 sensor cannot pick up an accurate oxygen reading so it's very important that your exhaust system has zero leaks. Last thing...you only need one sensor on either side to sample both cyl banks.
View attachment 150298

Tom,
Did you build your own headers or were they purchased? I am looking for double slip joint collectors in carbon steel and have only found one source - Stainless Headers. Most everyone supplies stainless but I want carbon steel.

Paul

 

[Tom]

Hi Paul! Yes, Stainless Headers has everything you need to duplicate my exhaust. No carbon steel on mine. You may be able to make your own double-slip outer pieces with an exhaust pipe expander, then weld them to the inner (primary) exhaust tube, once the collector is slid into position. I wonder if Stainless Headers can form the pieces out of steel for you?

 

[Paul Proefrock]

Thanks, Tom. Stainless Headers does have carbon steel with double slip joints, however they are the only ones I've been able to find. They are pretty competitive pricing-wise, but I would have liked to have found more than one just to make sure

I could form the outer pieces, but I can't find merge collectors with enough space between the tubes to allow their use. I purchased some collectors through Summit Racing however they won't accept the secondary tubes.

 

[Tom]

Paul, sorry to hear about the merge collector fitment issue. Stainless Headers merge collectors are nice, good quality, and blended internally. I see the mild steel sets available now on their site. I don't recall seeing them in the past. Good luck with what you decide.

 

[Ian Anderson]

Aircooled and EMPI for VW parts used to do them. Mild and stainless.. 1 1/2, 1 5/8 and 1 3/4 sizes from memory many years ago