someone please sticky this.

got this off of LCE's website. i do not take credit for this writeup. this is just a helpful writeup i found through their tech pages that came in handy for someone else.

LC ENGINEERING Carburetor Tech

 

Good stuff bro. I did this to my afm a few years ago and still goes strong with this little tweak.
I never did seal the black cap though due to frequent tuning.

 

i have wide band works very well when messing with the afm

buyt ya have to play with both air screw and spring tention

 

Autozone had some Sunpro AF gauges on sale for like $25 a few weeks ago. I bought 2. Works on any 2, 3 or 4 wire O2 sensor. Gonna use atleast 1 on my 78. Depends if I add another bank of cylinders if I need the other lol.

 

yea.. a wideband is the best way to go about tuning with the afm.

 

What makes them a wide band? The o2 sensor used or the gauge itself? The way the instructions to my gauge talks about it, they all have a signal and ground, the 3 and 4 wire are just self heating or something for quicker accuracy. Somebody wanna explain them a bit?

 

A wideband has a much faster sample rate, giving you more real time measurements. Stock o2 is slower . Its the sensor.

 

So if I was to get 4 wire instead of 2 wire sensors they would be better? Ill do that when I order bungs and sensors. I need to do some welding on my header anyways. Thanks.

 

Wrong

A narrowband O2 sensor can have 1-4 wires (sensor, heater, ground for each) Running separate grounds instead of using the sensor body and exhaust pipe means a cleaner signal and more stability.

A narrowband O2 sensor is just that: It measures a very narrow range of conditions. Without going into the chemistry and electronics, it basically acts like a switch. If you're rich, it reads ~.8v. once you cross the line to lean, the voltage will drop to ~.2v. Those are nominal voltages, in reality it varies +/-.2v. They're used because they're cheap and until recently, worked well enough. The ECU deliberately alternated running rich and lean to stay close to that crossover point (stoich). The downside (and reason you have to stay at stoich) is that there's no way to tell HOW rich or lean you are. it'll read pretty much the same thing whether you're at 12:1 or 8:1. (There are variations in chemistry and usage that reverse that, use 2-3v, 0-5v, etc but they all act the same. toyota uses 0-1v tho)

The gauges you see at parts stores (and most that are under $150) are set up to read this. They see a 0-1v input and display it. They show a range but in actual usage, it'll just bounce from one side to the other.

If a narrowband O2s is a switch, a wideband O2 sensor is like a dimmer. Chemically they're similar but hooked up and used differently. They have 5-8 wires and require a controller to run them and interpret the readings. The controller can be set up to output different signals depending on how you want to use it: mimic a narrowband, 0-5v graduated, serial output (for logging), etc. Because it isn't set up for a graduated signal, a computer meant to use a narrowband cannot use a wideband signal, the controller has to have a mode to mimic a narrowband or the ECU will freak out.

Some cars are now using them from the factory (most DI engines use them to run A/F ratios other than stoich) You cannot use a wideband without the controller (unless in the case of newer cars designed to use them, the controller is part of the PCM).

Tuning with a narrowband can be done but it's sort of a 'keep adjusting it till it changes then go back one notch' method.

 

Thanks a bunch! Sounds like I have some cheapie narrow band gauges. But, that should be better than nothing to assist tuning. I also have things like mixture screw position, plug readings and seat feel to help tune in for the right ratio. Plus carved engines change the mixture just by the outside air temp changing so its never perfect under all conditions. Ill deff be using 4 wire style sensors though. Seems the best way for what I have.