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Air Fuel Meters for AFR..which brand and model is preferred?


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OK, I've searched the archives and really only found one topic on this from back in 2009. I am thinking that there may have been some tech advances since then, maybe not. I know to purchase a wideband unit as well as where to place the sensor in the downpipe. I have a few more questions for any experienced user of these units.

1. Innovative sells a exhaust clamp for the sensor (for a temporary reading/adjustment), I am sure others sell one as well. My question is, will the A/F reading be any different from this point as compared to the sensor being mounted in the downpipe?

2. I am just looking to dial in the weber 32/36 carb, not to race, just want a well tuned, fuel efficient carb. Can I get by with just the 02 sensor and gauge or do I need a sensor module as well? I know I don't need USB hook up.

3. There are several AFR units out there (Innovative, Split Second, AEM, etc). My budget is around $180. What would you recommend?

I haven't decided as yet, whether or not to permanently mount the 02 sensor and gauge (so I can use it on other cars), however, the answer to #1 above might make that for me.

Thanks for the help!

1974 2002 Verona & 1973 2002 Riviera

1982 320iA & 1983 320iS
2002 Ford Excursion Limited 4x4 7.3L PSD Wife's

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I have an innovate with bung next to gearbox. Sensor died within 6mos. Got another, but have not installed yet. I did read about an enthusiast who had developed a better controller which works with a wifi router to send info directly to your phone or PC. I forgot the name of that and am searching again (not AEM -- though they have a wifi model as well). It was pretty reasonable too.

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Here is a link to the very informative installation/tuning manual for the AFX fuel to air ratio meter (made by NGK of spark plug fame).

It explains why the sensors fail early on some installations and how sensor installation affects readings.


No amount of skill or education will ever replace dumb luck
1971 2002 (much modified rocket),  1987 635CSI (beauty),  

2000 323i,  1996 Silverado Pickup (very useful)

Too many cars.

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I put in an AEM Mechanical UEGO gauge alongside a water temp and oil pressure gauge in my center console.

1) Check out this clamp that AEM makes that doesn't require welding a bung.


2) Both AEM and Innovate's guages are an all in one system that include the sensor module. The older innovate had a seperate sensor module and then a gauge but I don't think they sell it anymore. AEM also sells just a sensor module for applications that hook into a ems system or for hook up to an engine dyno.

3) Summit is selling the digital AEM gauge for 170 something, right in your range! http://www.summitracing.com/parts/avm-30-4100

you might not like the modern LED look, that's why I bought the mechanical sweep needle version

Good luck!

1973 2002 tii Agave


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I just dumped my Innovate and got this analog gauge. It's worked well for the past week. No calibration necessary.


Don't order from Autoplicity if you are in a hurry or expect customer service -- but their prices are good (although it appears they are not offering this gauge anymore!).



Ask me about my E10 320i's!
'73 320i /M2 2.5; '85 ///M635CSi ; '73 320i ugly car; '99 AMG C43


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  • 10 months later...

I just recieved an analogue aem gauge. That being said, the digital option in the rear view mirror was tempting, given that i have an extra mirror, and was planning to get my roof upholstery done soon.

1973 2002Tii (Pacific Blue)

1984 911 3.2 Carrera (Platnum Metallic)

2009 328xi (Black Sapphire Metallic)

2010 Mazda Speed3 (Black Metallic)

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might be the wireless you were thinking of.

I haven't bought any of his stuff... yet.


toalan seems to know his stuff.  Here is a read on Best Bang for the Buck: http://www.efi101.com/forum/viewtopic.php?t=8283

A radiator shop is a good place to take a leak.


I have no idea what I'm doing but I know I'm really good at it.

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Keep in mind that the AFR sensors and gauges are set up for straight gasoline.  If used with an Ethanol blend -- like a 10% blend, the AFR readings should be reduced by ~4% to give the equivalent Gas AFR.  So, a reading of 14 is equal to an actual AFR of 13.5.



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