Weld in O2 sensor bung location

[AMechEng]

Can and O2 sensor be welded in near the end of an exhaust system or does it have to be right on a primary near the engine where it is hottest? I've always had the impression that O2 sensor need to be very hot to operate correctly but my exhaust is ceramic coated. The "muffler" at the end isn't coated, it is stainless. It would be easier to weld in a bung at the tip.

 

[Rusty McNeil]

I think rule of thumb is within 30" or so of head. In any case I would think you want to mount it so that's its reading
more than just one cylinder.

Find what system you want and download the installation pdf's and it should tell you.

Right before the muffler on the mid pipe is usually good on aftermarket exhausts.
On the stock exhaust I mounted one into the giant collector box too.

Both locations worked well for me.

As far as mounting one at the very end of the muffler not sure, might be a little less responsive but then again Dyno a/f sensors usually just get poked up the exhaust pipe so that might be ok too.

What exhaust do you have?

A good welder should be able to mig/tig one in without damaging the ceramic
except right at the weld. I pre- drilled and fitted mine and just had it welded cause I didn't trust a welder to not go crazy with a grinder taking off more finish that was needed.

A WideBand sensor is self heating.

Don't know about the narrowbands.

 

[Buster Hymen]

Can and O2 sensor be welded in near the end of an exhaust system or does it have to be right on a primary near the engine where it is hottest? I've always had the impression that O2 sensor need to be very hot to operate correctly but my exhaust is ceramic coated. The "muffler" at the end isn't coated, it is stainless. It would be easier to weld in a bung at the tip.

Mine was welded in where all the pipes met on my Kerker, right before the exhaust can.

 

[AMechEng]

I have the UFO 4-1 with slash cut tip. The main collector is only a few inches before the tip so I guess if I want to read all four cylinders I can just weld it into the tip.

 

[Buster Hymen]

I can post a picture of mine this weekend, but it is basically right before the exhaust can, so somewhere similar on your should work.

 

[AMechEng]

Thanks

 

[шульц.]

not less than 0.5 meters from the end of the pipe. otherwise air will suck in reverse, the sensor will show lean

датчик нужно ставить не менее 0,5 метр от конца выхлопной трубы . в противном случае будет засасывать чистый воздух с улицы и датчик будет врать,показывать бедную смесь. . идеальное расположение -0,4 - 0,8 метр от цилиндра . так написано в инструкции к моему датчику. у lc-1есть свой подогрев,регулируется внутренним контроллером. поэтому важна не температура,а именно отсутствие уличного воздуха.

 

[06VMAXIMUS]

If you want to be able to tune each cylinder individually, you will need a bung at each. I kinda wish I would have done mine that way, but ended up putting 1 in each collector. I can monitor each side by just swapping the sensor around. Its a great tuning tool for sure.

 

[Rusty McNeil]

If money is no object you can buy 4 widenband kits and monitor all four cylinders.

I jest...

Seriously, even mega high dollar turbo tuner cars usually monitor just one bank of a V or Inline motor or sometimes both banks of the V's

I've never seen anyone monitor every cylinder. Although of course it can be done.
Probably Formula one cars do it I bet.

At some point you've got to place a little faith in your carbs, valve clearances and whatnot being consistently set up to yield consistent results.

If you try to pull too much data out of your setup and attempt to make all cylinders perfectly match based on WideBand a/f numbers you could easily end up chasing your tail.

Of course you could put in four bungs and just move it from one to the next but I still think its going to make you chase your tail. The ones I've dealt with weren't very good at giving solid idle numbers either which is about the only reason I would want to look at each cylinder anyway. But maybe one at each cylinder would have improved that?? I've never tried it admittedly.

Its bad enough when taking a perfectly running bike, adding one WideBand to it then deciding it needs perfecting further based on what your seeing.

Data overload with four if them.

Here's a tip as well once you get one. Don't be afraid to raise the "smoothing" setting on a WideBand fairly high. Otherwise the super quick responsiveness of these things will drive you nuts.

Every time you tweak the throttle up or down its going to go higher or lower than your "target" momentarily before it settles back out, driving you nuts if your a perfectionist.
This characteristic can never be eliminated on a carburetor bike.

 

[AMechEng]

not less than 0.5 meters from the end of the pipe. otherwise air will suck in reverse, the sensor will show lean

датчик нужно ставить не менее 0,5 метр от конца выхлопной трубы . в противном случае будет засасывать чистый воздух с улицы и датчик будет врать,показывать бедную смесь. . идеальное расположение -0,4 - 0,8 метр от цилиндра . так написано в инструкции к моему датчику. у lc-1есть свой подогрев,регулируется внутренним контроллером. поэтому важна не температура,а именно отсутствие уличного воздуха.

20 inches from the end and I am only reading 1 bank (2 cylinders). To read four cylinders I need to be 12 inches from the end. Can I ask what you are basing your statement on? I can't see how air would move into a tail pipe, especially above idle.

 

[Rusty McNeil]

I can't see how air would move into a tail pipe, especially above idle.

Not my statement but I'll try to help.

Exhaust reversion is always present, when the exhaust stroke is at TDC the exhaust valve is still open, when the piston starts coming down for the intake stroke it pull some of the exhaust gases back into the combustion chamber.

How much it does this is dependent on cam timing, profile, intake and exhaust overlap, duration etc. A cam that didn't do this at all would be a VERY mild cam, like maybe on a lawnmower. The more aggressive the cam, the the more it will do this. It's what makes that cool lumpity lump idle and it's also what contributes to poor throttle response on big cams.

This effect would be most pronounced in one pipe/one cylinder, when you start adding more cylinders like downstream of a collector the reversion effect at the sampling point is diluted.

Just my opinion based on what I "think" I know here but;

1. the reversion pulse can't be any greater than the volume sucked back into the cylinder prior to the exhaust valve closing, so you would have to be pretty much right at the end of the exhaust system to suck atmospheric (not exhaust) gas across the o2 sensor on the reversion pulse.

2. An o2 sensor doesn't "consume" its test sample so to speak, or if it does it's a TINY amount, so if it's far enough away from the end of the exhaust to avoid item 1 above it's still going to sample exhaust gas on the reversion pulse and not atmospheric gas.

3. The smoothing function/settings in the wideband should let you take this out anyway if it does occur.

4. I don't think any of the above concerns mean anything except at idle, above idle all of this is happening so fast reversion doesn't have much effect. The overall exhaust flow overwhelms the quantity of reversion.


There's no data available anywhere that would cause me to jet, clip, needle or spring my carbs differently between one and another. If I had to do that I'd be thinking something else is screwed up.

The only thing I would ever have different between one carb and the next is the a/f screw and there are tried and true methods to setting that already. I haven't found my wideband to be very consistent or trustworthy at idle, I don't even look at it until the throttle is cracked open and its over 1500 or so.

As far as how far away from the head I still say follow the mfgr's recommendations, mine said about 30" or so and definitely not between the head and a turbo unit due to the intense heat.

 

[srk468]

Here is where I put mine on my Kerker, if you were doing individual cylinders then you'd use an EGT probes and not a wideband O2 sensor.

 

[AMechEng]

Thanks for the post Rusty. All good points. I'll email Innovate Motorsports and see what they say.

 

[Rusty McNeil]

From the LM-2 Manual


2.2 Sensor Placement

Using a bung is the preferred method for mounting the O2 sensor for both catalytic and non-catalytic cars.

On CATALYTIC CONVERTER equipped vehicles:
Install the oxygen sensor’s bung upstream from the catalytic converter (a bung and plug is included in the LM-2 kit). The bung must be installed in the exhaust pipe at the side or on top, NOT on the bottom of the exhaust pipe. Any decent muffler or exhaust shop can do this for you. The wide-band oxygen sensor is then installed into the bung to take a reading. (Insert the plug into the bung when not in use). The ideal
position is between 10:00 and 2:00 position.

On NON-CATALYTIC converter vehicles:
You have the option with non-catalytic cars to also use an exhaust clamp as
described below. Use of a bung is the preferred method for mounting the 02 sensor for both catalytic and non-catalytic cars.

On TURBO CHARGED vehicles:
Install the bung downstream from the turbo but before the catalytic converter. The high exhaust pressure before the turbo interferes with the lambda measurement and the high exhaust temperatures encountered there can damage the sensor.

The maximum temperature of the sensor at the bung (the sensor hexagon)
should not exceed 500 oC or 900 oF. If these temperatures are exceeded in your application you should either install a double length bung (one inch) or the Innovate Motorsports Heat-Sink Bung extender (HBX-1).
The double length bung is also recommended for situations where airflow is restricted.

 

[Rusty McNeil]

Here's where I put mine, left side facing in at about 2:00 position on a 4-2 UFO system. It reads #2, #3 cyclinders

 

[wildweasel_pt]

The sensor should be fixed in between the 10 o'clock and 2 o'clock position. Like said the perfect setup is a bung per cylinder. One thing can be done and I want to do it, that is using a flo-commander system to tune the mix at 4 carbs at the same time, so the reading you get on a cylinder is exactly the same on all.

 

[davesax36]

So on this Hindle, could I just put one in the collector at the 4-1 spot?

 

[srk468]

So on this Hindle, could I just put one in the collector at the 4-1 spot?

Assuming you have room that would be perfect.

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