Where Did You Put Your Roadster O2 Sensor Bung

[RJD]

Greetings,

I'd be interested to see pictures of your O2 sensor installation for the Roadster. My concern for placing the O2 sensor bung now is how it will impact the body installation when the time comes to mate the chassis to the body.

The constraints for the Holley Sniper EFI is that the O2 sensor be installed 1 to 10 inches after the collector and have at least 18 inches of exhaust pipe left after the sensor. Also, the O2 sensor cannot be installed at the bottom of the exhaust tube.

This will be a clamp-on bung installation on the stock FFR pipes. Eventually I'll be going with GasN pipes and will have them install a permanent bung, so I want to get a location that will ultimately work for them as well without doing more modification to the body when I make the switch.

Thanks for your input.

[Papa]

Talk to Georgie (Gas-N) about installing a bung in the side pipe collector. He has the location worked out. I went with a header that has a double collector that makes O2 sensor placement simple and pretty much optimal for the EFI.

[phileas_fogg]

I put my sensor on the collector of my Gas-N pipes. Yes, the angle is below horizontal; and yes, I realize that I have not installed it per manufacturer's instructions. However, in the five years I've been on the forums I have not read a single thread about an O2 sensor failing due to improper installation. I even started a thread (https://www.ffcars.com/forums/17-fac...nsor-fail.html) asking if anybody's O2 sensor had failed, and got only one reported failure. So I rolled the dice, and will live with the result.

Incidentally, I ran the sensor wire through the body, up the side of the foot box, and behind the dash. You can just see the O2 connector behind the hinge in the last photo below. There's not enough room between the body and the 2" frame end for the connector, so I removed the pins from an extension wire, threaded it through the gap, and reinstalled the connector. Using the extension kept the individual wires off the edge of the 2" frame (I put some split hose on the end anyway), and gave me easy access to all O2 sensor connections.


John

IMG_4900 by jhsitton, on Flickr

IMG_4738 by jhsitton, on Flickr

IMG_4480 by jhsitton, on Flickr

[alv69]

0.2i put mine here made a hole in the body and put a big grommet in the hole.

[RJD]

Thanks everyone. I'll be incorprating your work. Much obliged.

[Big Blocker]

On my MKII.



Early "Beta test" version of what most header companies are doing now-a-days.

Doc

[caesarmascetti]

Greetings,

I'd be interested to see pictures of your O2 sensor installation for the Roadster. My concern for placing the O2 sensor bung now is how it will impact the body installation when the time comes to mate the chassis to the body.

The constraints for the Holley Sniper EFI is that the O2 sensor be installed 1 to 10 inches after the collector and have at least 18 inches of exhaust pipe left after the sensor. Also, the O2 sensor cannot be installed at the bottom of the exhaust tube.

This will be a clamp-on bung installation on the stock FFR pipes. Eventually I'll be going with GasN pipes and will have them install a permanent bung, so I want to get a location that will ultimately work for them as well without doing more modification to the body when I make the switch.

Thanks for your input.

This is an interesting question, I replaced my Mass-Flo unit, my original intent was to use a Holley Sniper but not one tech I spoke to out of three would commit that the system would work properly if I sampled only one header tube, the angle on the O2 was incorrect, or it was too far from the Sniper unit itself. Because of this I ended up with a carb a Quickfuel 600vs (per Mike Forte's advise).

[GoDadGo]

What Is An O-2 Sensor?

Sorry Gang, But I'm Back & Doing My Best To Get Back In To Proper Go-Dad-Go Form!

[Jeff Kleiner]

I've put them here:



Yes, below horizontal but none of the cars have ever experienced O2 sensor problems. Sometimes these cars require reasonable compromises.

Jeff


Oxygen sensor.jpg

[DavidW]

Who is the manufacturer for the Factory Five headers they provide, cant they have an option for some type of 4x pipe with an O2 bung in it for EFI sensors. Id like to see that option for the 351w headers. Kit owners could start off with carb then if changed to EFI in the future could just add the O2 sensor in the bung provided.

[Papa]

Who is the manufacturer for the Factory Five headers they provide, cant they have an option for some type of 4x pipe with an O2 bung in it for EFI sensors. Id like to see that option for the 351w headers. Kit owners could start off with carb then if changed to EFI in the future could just add the O2 sensor in the bung provided.

FFR is using BBK to make their headers. I agree that a double collector option offered by FFR would be good. Like you said, if you start with a carbed setup, just plug the O2 bung. If you later decide to go to EFI, unplug it and install the sensor.

[RJD]

I haven't read anything that frowns on putting the O2 sensor below the horizontal - just not on the bottom of the pipe. This is to preclude the sensor from being damaged by any moisture that may accumulate there.

[phileas_fogg]

I haven't read anything that frowns on putting the O2 sensor below the horizontal - just not on the bottom of the pipe. This is to preclude the sensor from being damaged by any moisture that may accumulate there.

Pretty much all the EFI systems instruct the user to angle the O2 sensor at least 10* above horizontal. Check out Figure 2 at the top of page 6 here: http://documents.holley.com/199r10653rev10.pdf

As Jeff says, sometimes these cars require compromises.


John

[Richard Oben]

No one ever said the mount had to be square with the side pipe. IE 90 degrees, just in the flow. We put them at the 5 or 7 o'clock position on the pipe but have them pointed as sideways as possible so they are not the lowest part of the car. We put more of the top of the bung in the pipe and less of it in the bottom of the pipe, it makes for some interesting welding but it works great. We also do not have to put a hole in the body that way. We have done this many times and so far no holes in body or broken O2 sensors. Going to do another this week. JMHO, Richard.

[DavidW]

I found these pictures on the internet, this is the way I would go in the header. The O2 sensor sticking out of the side of the body into the exhaust just doesnt look right to me.

[RJD]

All good info - definately glad I asked the question and appreciate the responses. Think I got it now. Looks like the goal is to keep moisture from entering the sensor and in a perfect world that placement would be angled above the horizon.

[Olli]

I went the double collector route.

Olli

[mdutton11]

Is there any reason not to use the bung on the top of the FFR 4:1 header for a sniper install? Mine is a driver and the sniper is in learn mode but won't get out of "closed loop" mode. O2 is the only thing I
have come up with.

[CDXXVII]

I had the guys at Stainless Headers build mine.

I am now running the Holley Terminator X Stealth TBI and I could not be happier.

IMG_2010.jpeg

IMG_1224.jpeg

[JMD]

You do realize this is a 6 year old thread you just revived, right?

Gas N headers now have a bung welded in and use a 'double collector' design. I put my O2 in the passenger side and plugged the drivers side and it works great for my Sniper 2.

[John Ibele]

Is there any reason not to use the bung on the top of the FFR 4:1 header for a sniper install? Mine is a driver and the sniper is in learn mode but won't get out of "closed loop" mode. O2 is the only thing I
have come up with.

That's exactly where you want it. And you want the system in closed loop mode essentially all the time, otherwise the ECU will not be using the information obtained from the O2 sensor to modify the amount of fuel to be injected by the injectors. While the system is almost always in closed loop mode, certain conditions have to be met in order for the system to enter learn mode. Closed loop mode does not go 'off' when learn mode is 'on'. In fact, closed loop mode being 'on' is one of the requirements to be met before entering learn mode. In closed loop mode, O2 sensor information about the fuel just burned is used to modify the amount of fuel to be injected by the injectors. When the system is in learn mode and the O2 sensor has been providing consistent feedback for some length of time (say, a certain % lean or rich with relatively constant RPM and throttle %), the ECU will use this information to update the learn table.

EFI is a deep dive for any first time user. And while the Sniper can get your car going 'out of the box', your roadster can't be truly enjoyed unless you do considerable tuning yourself or have a professional tune done.