Tell me about "Wide Band Air Fuel Ratio"

[prayers1 153]

I'd like to dial in my air/fuel mixture on my Quickfuel 735 carb. It's a bit of a challenge because the under hood air temp gets so hot with the Cleveland, I can only keep my had on the screwdriver for a short period of time.

 

So, I'd like to install a Wide Band Air Fuel Ratio Kit, but all that I see has one O2 sensor. I have dual exhaust what is available.

 

If you can give me some heads up on which is best to use and one that can be installed in the car.

 

Thank you!

[fordguy69 24]

Fast makes one that has two O2 sensors.

[Patriotgamez 14]

RU using the O2 sensors just to tune? I assume you have nothing to input the O2 sensor to...besides a gauge?

[juit 34]

http://faculty.ccp.edu/faculty/dreed/Campingart/jettatech/afr/

 

this article help me out a lot & bought the same one on that page, U also need a good vacuum gauge

 

install it in the H or X pipe if you have one

[1969vert 55]

I use a innovate motorsports O2 wide band in my car..

tuned idle / mid and wide open with it..took a little while but it is worth it..

I don't change plugs but once a year now..headers are a pain...I recommend it..

[prayers1 153]

A lot of A/F gauges only come with one O2 sensor, I want to put one in each pipe (dual exhaust). Where is the best place to put them, just after the header, at the H-pipe or after the muffler?

 

1969vert-Nice run at the track. I see your gas pressure stays constant. is it mech or electric? What are you using?

[j69302 11]

You Should NEVER put one in a H pipe. H Pipes balance pressure waves, not air flow. There is not a constant, consistent flow for it to be accurate in a H pipe.

 

Also you shouldn't, but can, put it in a X pipe. The reason being that you shouldn't is that the ideal place to put the sensor is in your header collector. The further away from the header collector, the more inaccurate it will be.

 

What type of intake manifold do you have? If it is a Dual plane manifold with 180* design, it does not matter which exahust pipe the sensor goes in. The reason being is on a 180* dual plane, 2 cylinders from each bank feed from one side. Example, Cylinders 1 & 4 (RH) and 6 & 7 (LH) feed from the same side of the carb, and 2&4 (RH) and 5 & 8 (LH) feed from the other. With this design, it will measure and average both sides of the carb through 1 exhaust pipe.

 

With a Single plane, it should still be ok to use in 1 pipe.

 

With a individual runner design (like webers) You will need a sensor in each pipe, or put it in the X pipe, which could be less accurate.

[prayers1 153]

I have the dual plane Blue Thunder intake for the 351 cleveland

 

Are you saying to place the sensor in the manifold port?

If not intake and not H-pipe then where should it go?

I can't place it in the header, their shorties and too hard to get in and out.

 

I was wondering, wherever you place the sensor within an exhaust pipe, will it restrict flow??

[Powershift 19]

You Should NEVER put one in a H pipe. H Pipes balance pressure waves, not air flow. There is not a constant, consistent flow for it to be accurate in a H pipe.

 

 

Many OEM setups use two sensors, with a factory H-pipe. So, that logic doesn't work.

[SWPruett 83]

Many OEM setups use two sensors, with a factory H-pipe. So, that logic doesn't work.

 

Actually, j69302 is absolutely correct. The OEM upstream sensors are always well ahead of the exhaust crossover (a.k.a., balance pipe) and are the primary feedback mechanism for engine A/F monitoring. The absolutely MUST be kept hot to function correctly and that drives an unending goal to get them as close to the head as possible for fast light-off of the cat and quick heating of the sensor.

 

On the flip side, the downstream sensors are always either in the catalyst bed or directly behind it to monitor catalyst efficiency and to close the OBD loop. These too are (almost) always ahead of any exhaust balance pipe to avoid signal confusion and cold-sensor inaccuracies. The bottom line is the further away from the heat source, the worse the sensors work. That is why all wide-band sensors are heated to maintain a minimum operating temp to ensure accuracy over a wide range of ratios.

[j69302 11]

Many OEM setups use two sensors, with a factory H-pipe. So, that logic doesn't work.

 

I didn't say you can't put them in an exhaust system with a h pipe, I said you can't put the sensor IN the H pipe.

 

In the systems you are talking about, there is a pair in front of the cats, and a pair after the cats. The cross over is usually after all cats and sensors

Edited October 14, 2014 by j69302

[j69302 11]

I have the dual plane Blue Thunder intake for the 351 cleveland

 

Are you saying to place the sensor in the manifold port?

If not intake and not H-pipe then where should it go?

I can't place it in the header, their shorties and too hard to get in and out.

 

I was wondering, wherever you place the sensor within an exhaust pipe, will it restrict flow??

 

The O2 sensors need to go in you exhaust pipe, as close to the header as possible. This is why the collector is the best place to put them.

 

Also, with that intake, you will be just fine with 1 O2 sensor in whichever pipe you can fit and install it in the best.

[1969vert 55]

mine is welded in 3" after the collector... so I could drop the exhaust and weld it in.. No room in my headers for the o2 sensor..

[70fastbak 16]

I could go on and on about this topic.

Ive had/built a lot of turbo mustangs, mustang cobras.

I personally have always used AEM wideband gauges and had good luck with them.

They have also come down in price considerably since I bought my first one.

It tells you right on the AEM turbo forums and the install instructions to have the O2 sensor no more than 18" from the manifolds because it has to be kept within a certain temp.

A good place to weld the O2 bungs if you run two sensors is just on the bend a few inches before the collectors or even in the collectors.

Remember to angle the sensor at around a 10 degree downward angle so moisture does not collect in the sensor tip.

Just make sure to go with a good wideband, innovate LC1 is another good one, stay away from narrowband they are nothing more than flashing disco lights in your dash/pod that tell you nothing.

You should be fine using just one sensor but ive seen two in dual exhaust cars also.

Most of the turbo cars ive had I fabricated my own kits and they have ended up being a 4" single exhaust right from the turbo back into a muffler so ive never had a reason for two sensors.

Edited October 15, 2014 by 70fastbak

[stangme428 33]

I went with the AEM unit and had the exhaust shop weld in a bung for the o2 sensor when i had my exhaust installed..

[prayers1 153]

Thanks, a lot of good info here. This is my first go around with anything related to A/F gauges.

 

When I had my exhaust built, I had it built in sections so that i can pull both pipes off before the H section and still leave in th headers and H pipe on, this way it would beeasier to pull the AOD trans.

 

As i understand, i only need one bug and place close to the colletor.

 

I assume the sensor is at least 2" long. will it cause a restriction on exhaust.

Where to place it on the pipe, 12, 3, 6, 9 o'clock position.

Someone mentioned at 10 degress angle, because rust forming from condensation.

 

Any other tips or ideals for installation.............

[j69302 11]

The sensor is not supposed to protrude all the way into the pipe. The bung sets the depth of the sensor. Use the bung and sensor from whatever kit you have.

 

It should be angle up. anything between 10 and 2 o clock will be fine.

[Rip Rock 13]

I always put mine at the collector on an n/a car. Put it on the leanest cylinder side collector. You can buy a clamp on bung so you don't have to weld on the bung. I recommend welding it on.

 

There are 3 a/f gauges that everyone uses(most popular). Aem,lc1 and zeitronix gauges.

 

If your worried about restriction, you can buy or make an 02 extension. I have never done this because I think it won't be as accurate.

[1969_Mach1 333]

Prayers1,

 

I have no input for the wide band O2 sensor, never used one. But, how hot is this motor getting that you cannot hold a screwdriver long enough to make adjustments?

[prayers1 153]

The motor runs 180*, but I have the 4 corner mixture screw set up. Because of the Export Brace being in the way of the right rear adjustment and the heat from the headers and intake, I can only keep my hand there for a few seconds after the motor is fully warmed up.

 

Thank you all for the great info, If things don't change I'll more than likely get the AEM set up.

[jmlay 80]

Put the bung in the exhaust pipe right after the header collector or the exhaust manifold. This way if you have coated headers you do nit disturb the coating & a couple of inches difference you are not going to notice. I would put one on each side & tune on one side then check the other.

 

http://www.innovatemotorsports.com/resources/carb-central.php

[j69302 11]

I would put one on each side & tune on one side then check the other.

 

 

Again, with a dual plane manifold, this is not necessary, and can actually still give you mis leading numbers because each pipe shares 2 cylinders from each side of the carb. With a dual plane setup, you will always get an AVERAGED air fuel ratio from both sides of the carb, regardless of what pipe or pipes, the senor or sensors are in. The IDEAL way of doing it, would be put 1 sensor in whatever pipe it fits best. Tune to get a proper air/fuel ratio.

 

Then check plugs 1, 4, 6, 7 against plugs 2, 3, 6, 8. If one set of those numbers look more rich or leaner than the other, then an adjustment to that side of the carb need to be done, to make sure both sides of the carb are balance properly. Using a second sensor, or moving the single sensor to the other pipe, will only cost more money and more time.

 

Here is how a dual plane manifold works:

 

CYL --------------- CYL

LH BANK -----------RH BANK

 

5 (CARB LH) ----- 1 (CARB RH)

 

6 (CARB RH) ----- 2 (CARB LH)

 

7 (CARB RH) ----- 3 (CARB LH)

 

8 (CARB LH) ----- 4 (CARB RH)

Edited October 16, 2014 by j69302

[jmlay 80]

Maybe not needed but for the for the cost of the bung & a plug it is worth while.

[prayers1 153]

j69302-Good explanation and you even have a picture of the BT manifold. Are you using any A/F gauges. How do you know so much about it.

 

The main reason I'm going about it, is because I have the 4 mixture screws which seems a lot harder to fine tune than the 2.

 

I have ordered the AEM wide band, so it will be a while before I get the exhaust fabbed up and all installed, so in between that, do you have any pointers on fine tuning.

[j69302 11]

Maybe not needed but for the for the cost of the bung & a plug it is worth while.

 

Again, by moving the sensor over to the other pipe, you will be reading the same average air/fuel ratio as you would in the other pipe. If one side is more lean than the other, then there is a vacuum leak on the leanest side. That is all it will tell you by moving the sensor - and you down need a o2 sensor to find a vacuum leak.

 

j69302-Good explanation and you even have a picture of the BT manifold. Are you using any A/F gauges. How do you know so much about it.

 

The main reason I'm going about it, is because I have the 4 mixture screws which seems a lot harder to fine tune than the 2.

 

I have ordered the AEM wide band, so it will be a while before I get the exhaust fabbed up and all installed, so in between that, do you have any pointers on fine tuning.

 

I use a hand held innovate LM-2. It only does one sensor. They do sell a version that supports 2 sensors, but again, its not needed. I have used it to extensively tune my cruise and full power air/fuel ratio. You do not need a sensor to tune your idle system.

 

What carb to you have? You dont need a o2 sensor to adjust the idle mixture. You should be using a vacuum gauge, and adjust the screws until you get the highest vacuum reading.

 

Since you have a 4 corner idle system, this is how I would do it. With engine off, screw in all of the idle mixture screws all the way, then unscrew 2 turns.

 

From there, warm the car up, and simultaneously adjust both screws on one side of the carb at a time. Adjust them the same direction and same amount. Once you get the highest vacuum reading, give it a couple good revs. Then do the same to the other side. I dont know how much airflow difference there is between the primary and secondary on the same side of the carb. You may end up having to independently adjust to fine tune... but the key is to have the 4 corners balanced.

 

Repeat the procedure once or twice, if it is way off, you may even have to adjust the idle speed screw and then do the whole procedure over again.