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AFR Meter


FBBO Gold Member
FBBO Gold Member
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10:33 AM
Sep 24, 2020
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Holley, NY
I am looking to purchase an AFR meter, so I'm looking for some recommendations. I don't intend to permanently install it in the car, just want to check and adjust my set-up, then put a plug in the weld-in bung. Looking forward to some input.
You can find a myriad of them on Amazon that come with the O2 sensor and a long enough cable for testing purposes.

Recently went to a buddy place and got my Street Demon's AFR set up nicely and his unit was a normal gauge that you would mount inside but he has it in a case to use portable with a long cable that we just ran up the door from the bung.

Amazon also sells many threaded plugs for the bungs.
I have a digital autometer afr gauge that I permanently installed. It's nice to know what it's doing all the time.
I use an innovative LM2. I just put it into whatever car I’m tuning at the time. It’s been in several, Works well. Also pretty easy to use. It will data log and such but I haven’t got into really needing that. It can also run dual sensors which I’ll be using when I tune my cross ram’d Hemi. It also uses a Bosch sensor which is readily available.

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I was under the same mindset as you as to just using the A/F meter for tuning. Then I had a couple things happen in different cars. First time was when I was messing around under the hood for something, and must have bumped the big vac line off the back of the carb. Got in the car and my meter was way lean, but it ran fine. I would have driven off with a 20+ A/F reading. Second time I was out for a cruise and everything was normal. Next time I looked at the gauge, it was a couple points higher than normal. I drove it home 10 miles because it wasn't terrible and was running ok. Popped the hood at home and found that #4 spark plug wire had come off. Never had that happen before. After that, I stuck a A/F meter in each car and left them there.
I have a FAST test unit I would like to sell. I used it one time. PM me if you are interested.
I use an AEM. I know there’s people here that just say “read your plugs,” to that I must say you don’t need a temperature gauge just feel the hose, you don’t need an oil pressure gauge, just check the dip stick. Like hunt2elk, and Aron Gleason said, it’s nice to know what’s going on.
So, what does one have to buy to put this set up in there car? Gauge, sensor, bung?
Yes. You drill a hole in one of the exhaust pipes no more then 18” from the collector, weld an o2 sensor bung in, then whatever AFR gauge you get will have all the fun wires and o2 sensors you need.
Ideally you try to mount it at 45 degrees or vertical if possible.
Moisture on the sensor can ruin it.
A few years ago I bought a PLX Technologies unit. Bought the bungs and plugs for same had it welded on outside of pipes as directed, so bungs are reachable without jacking up the car. Not a permanent installation, but temporary use for tuning. Just run wire from sensor outside thru window while driving for testing. Bought a lighter plug to power the unit. Nice thing about this model is it has Bluetooth so, you can install an app on your cell phone to monitor readings. Nice and easy when needed.
So with stock manifolds and dual exhaust with h-pipe, with no crossover in the intake manifold, where would the bung be installed?