How to: measure fuel mixture

[wxo]

I came across this website and found it very interesting.

http://www.thirdgen.org/o2tuning

I wonder if I could install an O2 sensor in my truck exhaust, hook it up and then use it to tune the jetting on my Holley.

[TireSmoker]

I came across this website and found it very interesting.

http://www.thirdgen.org/o2tuning

I wonder if I could install an O2 sensor in my truck exhaust, hook it up and then use it to tune the jetting on my Holley.

You could very easily do that Walt. An exhaust shop charged me $20 to weld a bung into my header (off the car). You could grab an O2 sensor from just about anything in the bone yard. There are typically 1-wire, 3-wire, and 4-wire O2 sensor.

1 Wire = signal only
3 Wire = signal, heater power, heater ground
4 Wire = signal, signal ground, heater power, heater ground.

Narrowband sensors put out a 0-1v signal, with .5 being stoich (14.7:1), over .5v is rich, under .5v is lean. They are only accurate at .5 though. IE-- outside of the .5v range, you only know that you are rich or lean, but not by how much.

If you want to get spendy, you can buy a $300 setup from Innovate Motorsports (LC1 + XD1) that will tell you your exact fuel ratio at any point.

With either sensor, you need to make sure you don't have any exhaust leaks in the system. (upstream of sensor)

-Dave

[wxo]

From a practical point of view, does it make any sense to put sensors in both sides and change jets accordingly? I'm not sure how far to take this thing. Maybe just verifying the gross jetting on one side is as good as it gets. I dunno.
Also, do you suppose there is any benefit to one-wire sensor versus multi-wire sensors?

[MostMint]

Unless there is some type of problem with a cylinder, or you have modified the heads or intake, I would think it would be fairly safe to put in one sensor and assume both sides were behaving the same way.

I guess reading the plugs isn't good enough these days.

[TireSmoker]

I would agree that one sensor is going to work well, at least for these purposes. I recently read a thread on thirdgen.org where the guy was measuring between the two banks and found a difference of 1 AFR-point and has been ripping his hair out trying to find the problem.

The 1-wire sensors need to be closer to the engine so that they stay hot enough to work during idle and low-load operation. The heater in the 3-wire and 4-wire allows more flexibility in terms of location.

-Dave

[wxo]

Thanks, Dave, great info. I'll shoot for one multiwire sensor. I'm assuming that all O2 sensors have the same bung size and threads. Right?

[TireSmoker]

Yes, they are all the same thread.