Use 02 sensor for wideband (air/fuel-ratio) - JeepForum.com
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post #1 of 7 Old 09-14-2021, 01:35 PM Thread Starter
DLantz
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Use 02 sensor for wideband (air/fuel-ratio)

Hi all,

Since I've done the nutter and the computer is out of the equation, could I use the factory 02 sensor and hook up an air/fuel ratio gauge to it? Or would the 02 sensor need to be replaced?

Would be interesting to actually have a reading since the carter is somewhat tricky to dial in. Also just to be able to see if I'm running way rich or way lean...

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post #2 of 7 Old Yesterday, 01:28 AM
BagusJeep
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I believe it is a narrow band i.e. it only tells the computer high or low of the mark, it is not calibrated to give accurate readings. i could not find full specs but I suspect given its age that it measured between 14.6:1 and 14.8:1 and probably is struggling if it is an original part as they crap out after about 10 -15 years or 60,000 miles. It is one of those parts that you don't realise is worn out until you replace it, and your mileage improves.

Looking at the wiring diagrams it is not heated. A modern 4 wire narrow band sensor would self heat whilst the engine was cold, not wait for the exhaust to heat up. Early technology.

To run an AFR meter you will need the right one for the meter which is possibly a 5 or 6 wire. This may have a range of 10:1 to 20:1 air fuel ratio.

I checked a basic Autometer gauge which will measure 10:1 to 18:1 with a heated sensor. They start around $200. For me this is a lot of change but will it be as fascinating as guessing Empty on the fuel gauge?

BagusJeep lives in Bali with far too many 4x4s:
1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
1980 Land Rover Series III 109" troop carrier - ROVER
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post #3 of 7 Old Yesterday, 03:52 AM
JD Blaine
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Bagus is right, as narrow band sensors only read 0-1 volt. Wide band measures 0-5 volts, and are widely available in the $50 range. Just make sure to get the right one for your gauge, as there are 2 different styles with two different plugs. Lambda and AFR. We used to use AFR all the time when running a Powersports dyno, but they were cheaper and would foul quicker than a Lambda. We never switched to Lambda cos the dyno was getting used almost everyday. No need to worry about which one to get if you’re buying a gauge/sensor package.

Just keep in mind that getting/keeping stochiometric readings doesn’t always mean you’re getting the most power out of your engine. Sometimes in certain Rpm ranges, you’re engine will like a leaner or richer mix. It will definitely help out identifying overly rich or lean conditions. I still install a gauge in my stuff just because it’s fun to watch the changes while driving….which my wife tells me is as bad as using a cell phone while driving…lolololol…
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post #4 of 7 Old Yesterday, 06:07 AM
Axhammer
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My Innovative Motorsports LM-2 air/fuel meter calls for the O2 sensor bung to be downstream from the exhaust collector 24”. The O2 sensor on my 258 is located before the collector on the exhaust manifold, so based on location alone, I don’t think it’s a good idea.
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post #5 of 7 Old Today, 03:51 AM
keith460
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Quote:
Originally Posted by Axhammer View Post
My Innovative Motorsports LM-2 air/fuel meter calls for the O2 sensor bung to be downstream from the exhaust collector 24”. The O2 sensor on my 258 is located before the collector on the exhaust manifold, so based on location alone, I don’t think it’s a good idea.

I have the same one and originally wanted to use the factory location for the 02 sensor but decided not to based on manufactures recommended location. I don't know if the readings would be off or if the factory location would damage the 02 sensor or if it just plain easier to add the 02 sensor bung to a head pipe instead of exhaust manifold. Many OEM cast iron exhaust manifolds don't have 02 sensor fittings in them.


Had some photos of it but can't find them now.

.
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post #6 of 7 Old Today, 05:46 AM
Axhammer
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In this picture of my 1985 258 with Howell TBFI, you can see the O2 sensor in the cast iron exhaust manifold, above where it connects to the exhaust pipe.

In the second picture underneath the Jeep, you can see the O2 sensor for my LM-2 air/fuel meter. I moved it as far away from the exhaust collector as per the LM-2 installation instructions.

In the third picture, you can see the bung for the ECM is at the other end of the same pipe, just downstream from the collector connection, the same location as the OEM 4.0 design.
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Why do I own a CJ? I like to “Balance the wrench and the steering wheel”
1985 CJ-7 Sebring Red, White hardtop, 284 CID inline six (4.7) TF 999 auto
2020 JLU Black, Black hardtop, EcoDiesel, 35’s on 2” Mopar lift
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post #7 of 7 Old Today, 01:03 PM
cdt540
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Quote:
Originally Posted by Axhammer View Post
My Innovative Motorsports LM-2 air/fuel meter calls for the O2 sensor bung to be downstream from the exhaust collector 24”. The O2 sensor on my 258 is located before the collector on the exhaust manifold, so based on location alone, I don’t think it’s a good idea.
I have the same setup. I initially used the stock location for the A/F O2 and went thru three O2 sensors until I had a bung put in further downstream. No issues since.

Chris
'83 CJ7 (258 5 spd)
Austin, TX
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