Technical Air/ Fuel Ratio Gauge Installation

Re read what Squirrel said a few posts back. It's nice to have the A/F info in real time but it's not as critical with a N/A engine with a carb. If it was boosted engine I would recommend it. You dont want to be lean under boost.

 

Phil, I wanted to thank you for all of your helpful & useful information in regards to my questions about A/F gauge usage... On most days I'd just tell you to F--K OFF !!! But I'm having a really great day, my engine builder called, and yesterday the wiring guy called to make an appointment, so I'm not going to tell you to F--K OFF!!! As I said I'm having a great day and I hope you are TOO.. Thank you for your time, dyno dave

 

Its like most things anyone trys to learn about. At first there is a big haze with all the info trying to be absorbed and associated in your mind............but once you start doing the hands on stuff it gradually becomes more understandable and somewhat easier. There is always more to learn about everything, but most of us can absorb enough to make what we are doing work acceptably. Then as time goes on we improve it some more.

 

Thank you for posting this, it is what I'm dealing with...Being told to bump the jetting by 10%, which I do understand in a race car to the mat application... Can't get around the suggestions for a 10% increase at idle and at mid-range for a street car. Thinking that the car would be running rich in both idle & mid modes, but good in wide open throttle. For a retired senior on a limited hobby car budget this is a somewhat pricey purchase, was trying for some assurance that this would be a good way to go to achieve the desired results... Again, thanks... dyno dave

 

I bought a really nice looking Innovate A/F gauge plus a wide band O2 sensor, then discovered I need a "controller" in there as well to run the system.
I think the gauge posted earlier also needs a controller, so make sure to look into that when buying stuff.
These controllers can be rather pricy, and add more complication.

 

Is that "controller" for data logging or necessary for gauge readout only?

 

As I understand it, the controller is needed to get the gauge to read and function at all.

But I'm not really knowledgeable on these things. Just that the manufacturer says a controller is needed. The unit referred to in the link in post #4, for instance, is advertised thus:

• Air Fuel Wide-band Controller and sensor not included

"...gauge is factory setup to work with Innovate's LC-1 and LC-2..."

which don't show up on a search of that site.

 

My understanding is that the controller is built into the guage to make it work and that there are 4 wires and 2 connectors. The connectors plug into the guage. The wires from one connector go to the O2 sensor and its simply a matter of pushing the connector into the guage socket. The other connector plugs into the guage also and has 4 wires sticking from the other end.
1. One wire to switched 12 volt source
2. Ground
3&4 are only used if you want to send the info to a data logger or something but are not necessary otherwise.

So, my understanding is basically hooking it to a hot wire and a ground will allow the guage to function.

There are harnesses available that have the controller built in and they can be hooked up to some guage panels instead of using a stand alone guage.

Right or wrong, thats how I think it works......

 

A wide band O2 gauge is a good tool for every day driver ,Sunday driver or performance .. nowadays if you are running gas/ fuel off the pump ,plugs will always look rich , ( also combined with different oil manufacturers chemistries /formula)
I have debate this point before look at modern NEW Vehicles look @ tail pipes always look black /Rich !!! it's just the blend and formula of the newer fuels unless you're running race gas , The Manufacture brand of gauge makes a big difference,& 02s , O2s depth is critical also, . Different clocking of O2 you will get different readings in different locations I have ran up to 10 different locations 1 to 2 in each header tube, & different (combination of headers ) locations on main pipe / collector back or Zoomies On carburetors or carburetor I Tunes off (SBC ) #6 is the Leanest of the 8 banks / cylinders. Standard firing order
18436572 . (Cylinder fire order swap would be different )
On EFI with a good ECU I will tune each cylinder differently by controlling the injector on Each Cylinder. Like mechanical fuel injection. A good Single wide band gauge is going to start at $ 200+ !!!
I also use Data logger , with EGTS Each cylinder. It just depends on how far you want to go , how much time do you want to spend into finding more information.

 

Heres what I know from my EFI days, earlier O2 sensors needed to get to around 600 degrees to function properly, these were two wire sensors. Since OBD2 came out the O2 sensors are heated. I’m guessing that’s the case (heated sensor) to work. I might be off base, but if I’m correct you should be able to put them where you want.
On the OBD1 cars the O2 sensor was in the manifold, now on my truck I have 4, all heated. Don’t recall where the upstream one is at, but the downstream ones are a good 3 feet (guess) from the manifolds.

I guess I’m saying you can locate them where it’s convenient.

 

Best results presumably would be to imitate the most similar OEM configuration to decide where to put the O2 sensor. The heated (four wire) O2 sensors were used way back with OBD1, as on the '92 Escort in my family fleet.

The downstream sensor is only used to determine if the catalytic convertor is working properly. It most likely will not respond quickly to changing engine operating conditions, but is referred to in certain driving conditions (fully warmed up, steady state driving etc.) to see if its output is the same as the upstream, primary sensor(s). If different, then the brain concludes there's a problem with the cat [edit: I got that backwards].
If it detects a problem the computer will just generate a code, it won't change the running of the engine.

 

I think you know what you meant, but mis-stated it.

In an EFI OEM vehicle the when the engine is cold it operates on a pre-programmed set of values that allows the motor to be operated in a rich fuel condition like a choke would provide with a carburetor. When it is operating in that mode, the computer does not use any information provided by the primary (closest to the engine) O2 sensor. When operating in the cold/rich mode, it is called "open loop" operation.
The thing to realize is that the newer type O2 sensors actually measure the amount of oxygen (as compared to the rest of the exhaust)......and they can do this whether the engine is running rich, stoic, or lean.
That ability allows it to work with a carb which has no computer.

As the exhaust continues past the primary O2 sensor it comes to the catalytic converter for processing into EPA acceptable exhaust. This is where I think you just said it backwards. "If different, then the brain concludes there's a problem with the cat." The second O2 sensor is there to make sure what went into the catalytic converter actually is different after it passes through the converter. Thats why the converter is there. Like I said, I think it was a simple brain fart like I get a lot of the time.

Also, early O2 sensors were basically a "0" or a "1" output while the newer ones provide a range . Thats why they have begun to find favor with carbureted vehicles.......they can tell you the ratio no matter what the engines mode of operation with a carb. In newer OEM injected vehicles with computers, they still use the "open loop" mode when the engine is cold. Once the engine warms to a certain temperature, the OEM computer has a sensor telling the computer that the engine is warm. Similar to the sensor that an electrical temperature gage has. The simple reason for doing this is that cold engines operate better with a rich mixture and don't need the input of an O2 sensor. When the engine is warm, it switches from "open loop" to "closed loop".......which simply means that now the computer is accepting and processing the info coming from the O2 sensor.

I think Beanscoot already knows all this, but I wanted to explain and clarify the info for anyone else interested in how it works.

One last tidbit.......one of the confusing things is that many people think all these sensors send "codes" to the computer OR the Guage if installing one for a carburetor. Thats NOT whats happening. The voltage used is a reduced 5 volt reference voltage. It has to be a voltage less than 12 Volts because battery voltage can vary a lot. So the 5 volts is read by the computer or the controller in the guage. As different metals change temperature, their abilty to transmit electricity changes........which changes the voltage it passes to the computer or guage. Thats all thats happening........varying voltage, not sending special codes. Didn't want to talk about late model stuff, but I think thats the only way someone can see how the O2 guage works and how it can help with a carburetor.


So, quick summary............

When a EFI engine is cold it does not utilize info from O2 sensor = OPEN LOOP OPERATION
When a EFI engine reaches operating temperature it recognizes O2 input= CLOSED LOOP OPERATION
When an O2 sensor is used with a guage and a carburetor it reads all the time whether the engine is cold/hot/idling/accelerating/decelerating/whatever

 

Won't a O2 sensor work without any power input? Can't you hook them to any digital or analog meter and read what is happening in the exhaust stream. You need to convert the data, but it's doable.

I was a car show that had a late night cruise up and down main street, with 1000 cars moving about, the exhaust smell was overwhelming making those close to the action sick. I know I was light headed for hours and made the drive home extra long. 75% of the cars could have used a A/F gauge and leaner metering!

 

Quite so, thanks for correcting that. I don't like to post bad information.
I'll add an edit to my post.

 

Thanks!

I recently posted some incorrect information on another site. It was basically an oversight on my part when weighing a rod......forgot to remove the rod bearing. From that point all my calculations and information was incorrect. Later I caught my mistake, so I went back in and posted a note admitting that I erred and the info was wrong. Then I posted the corrected information as a follow up. We all hate it when we make a mis-statement and don't actually say what we meant to say..............but we all do it some time or other. Like you, I want what I say to be correct, so others can rely on what I say. And when I err, I want to know that too.

 

And speaking of erroneous information, maybe one day a research team will be assembled to actually measure all those stock 8 and 9 inch differential widths and correct the screwy charts endlessly copied on the internet.