Installing an Air/Fuel Ratio Gauge. Need o2 sensor help

If memory serves the Insight burns as lean as 22 to 1 if that answers your question.

Rick said:

If memory serves the Insight burns as lean as 22 to 1 if that answers your question.

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I'll be throwing it in my CVT, so I shouldn't be running THAT lean.

I've been planning the same thing. Based on readings from the OBD tool, the output of the LAF sensor is the 0-1V as expected, so it is compatible with that gauge. HOWEVER, the LAF has two signal wires, so you will need to probe the wire with a HIGH IMPEDANCE voltmeter to determine which represents the most compatible signal for your A/F gauge. This is only my list of things to do. The A/F gauge will easily serve as a "lean burn indicator", since the output of the LAF sensor drops to about ~0.2V steady under lean burn. Of course, since you have a CVT, you don't have lean burn...

You can also connect the gauge to the more conventional sensor after the cat, but the readings will be skewed...

Never mind then because the CVT does not have lean burn at all unless you have a Japanese version of the car.

Did anything come of this previous discussion about air-fuel ratio meters? I was thinking that you might be able to just connect a voltmeter to the terminals on sensor 1.

Also, what is the "air fuel ratio sensor relay" for? It's next to sensor 1 in the shop manual.

Goal would be to have a light that shows "in lean burn mode."

Dougie said:

Goal would be to have a light that shows "in lean burn mode."

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You already have one, of a sort.

The MPG meter will indicate when you hit lean burn. It just takes the seat-of-the-pants "computer" to interpret speed & load to determine if your "coasting" or truly in lean-burn.

An "idiot" light for potential hyper MPG is almost an oxymoron.

HTH!

Yes, I understand that. But in the hilly area I drive in it's not so easy to tell whether the high reading is because of lean burn or because of going slightly downhill.

It seems to me that it should be possible to look at the output of the sensor to see whether the system is maintaining a 15:1 or a 20:1 ratio. Certainly you can buy such a system for a few hundred bucks.

You just need to "calibrate" the steering wheel to seat connection.

Seriously & IMO such a light would be redundant, think about it. Want better MPG :?: Just keep the MPG reading high. It doesn't matter if its due to lean burn or not.

But yes with some advanced electronics knowledge and tinkering such an circuit tapped into the LAF could be done.

Dougie said:

Did anything come of this previous discussion about air-fuel ratio meters? I was thinking that you might be able to just connect a voltmeter to the terminals on sensor 1.

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It's on my long list of things to do with the car...

However I believe the information I posted above is incorrect. Checking the service manual reveals that the signal from the LAF sensor is a 0-5V signal. The OBDII tool must represent it as if it is a standard O2 sensor and not a wideband type.

You can use a voltage divider network to bring the voltage down but I think that may present impedance issues. At this point it's probably best to mount another O2 sensor after the main cat. The readings will be all wrong though, and I suspect that unless you use a wideband it's going to be off the scale lean shortly after the car starts.

Aaron Cake said:

The OBDII tool must represent it as if it is a standard O2 sensor and not a wideband type.

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:?

IIRC in an older thread several members took LAF O2 readings while in "known" lean burn, 1.5x V and lower :?:
Scan tool reports indicate that its output is shown as a "flat" voltage vs. a sweeping non LAF type O2 sensor's output.

Dougie said:

Goal would be to have a light that shows "in lean burn mode."

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It would be easier to buy a Scan Gauge II and set one of the gauges to read ignition advance. If it reads over 50, you are in lean-burn.

Infidel said:

<snip> read ignition advance. If it reads over 50, you are in lean-burn.

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And another: :?

Haven't seen anything like that with my scan tool forays. :?

But a scan tool could display LAF readings. And there is a voltage threshold that IS "lean burn".

Here's my advice. Check out the primary O2 sensor, between the cylinder head and the first cat. If it has 5 wires then it's a wide-band sensor and you can not use it with your gauge. Use the second o2 sensor located after the first cat. It should be a standard 4 wire model.

You want the black wire.

Good luck.

Sorry flunkysama.

That would be correct ONLY for the 00-02 model years. IIRC somewhere in mid 02 and later the LAF was "morphed" into a 4 wire connector (but its stlll a LAF type).

Tapping into the 2nd sensor and interpreting the "lean-burn" condition will be a bit tricky since its "seeing" the CAT effect too.

HTH!