I have an A/F autometer gauge installed. But I'm wondering if its really useful.

First off, no car is the same, how does it know if it runs lean or not?

Also, it doesn't work until the O2 sensor heats up. But what about when you go at WOT for a minute? The exhaust will be red hot, so does the O2 sensor readings change for the A/F gauge?

And what is my reading supposed to be for those of you who have it? Mine is right on the first line off rich. Is that normal?

Thank you.

 

is it a narrow band?

 

No. Autometer A/F gauge. Otherwise I would have said wide/narrow band

 

I had it on my NA, connected to the stock 02 sensor; and it was absolutely worthless

BTW - The readings that you are seeing (first green line, when the car is fully warmed) are normal.

 

Why?

Normal as in perfect? And if it goes down, does it really mean I'm leaning out? Example: My fuel pump is not rewired, if its lacking voltage, will I notice it in the gauge?

 

The stock o2 sensor is a narrowband.

So the a/f gauge is only good for widebands, since they are more comprehensive.

 

Meaning? That still doesn't answer my questions.

 

Anyone?

 

basically a narrowband is just a bunch of blinking lights, it won't tell you

i've had one installed for about a year, theres really no discernable pattern for the lights that will give you any info

 

So its useless. I paid 70$ for christmas lights?

 

I just want to clarify that the Autometer as well as the Cyberdine or any other A/F gauges are not accurate as far as telling you if you’re running lean or rich on the fly. Those gauges are more for show than anything inside the cockpit. My personal opinion is they serve no use as a tuning aid. To answer your second question in order for the gauge to work the O2 sensor needs to be heated up. If you really want to monitor your A/F ratios properly I suggest you spend the money and go with an EGT gauge with the O2 sensor that you tap into your downpipe in your car. At the same time once you install that gauge I would go to a dyno and do a few pulls with a wideband of course to see what numbers you’re getting as far as A/F is concerned. If you really want a useful tuning aid I would get a PLX R-300.
There not cheap, but there definitely worth the money in my opinion. I’m going to get one myself. I spoke to "Mike" at PLX, "nice guy by the way" and he said the PLX R-500 is sold out for a few months. I’m going to get the PLX R-300 which is cheaper in price than the PLX R-500; the only difference is it has no knock sensor or G-sensor like the PLX R-500. There website is www.plxdevices.com

 

The narrowband is only useless to those who do not know how to use it:

https://www.rx7club.com/forum/showthread.php?t=588112

 

mostly.

 

a narrowband will tell you if the car is in closed loop, yes. but that helps very little when you are under boost...

 

I found mine useful.
A wideband is best for tuning a turbo, but it can still tell if something's wrong.
One time it showed me going lean under medium acceleration - the FPR hose had blown off.

 

Have you ever used the Autometer AFR gauge? Trust me it is useless...

 

Yep, and no, its not useless. Trust me.

They're very useful for many scenarios - heck, my Haltech uses the narrow band sensor for closed loop, probably saves me 5-8mpg. Thats not useless. The gauge has next to nothing to do with the equation.

 

Can someone answer this simple question.

If I start to run lean, at any rpm, will I notice the difference on the gauge?

And what does Closed loop mean?

Thank you.

 

Well, there's no absolute answer to that question when dealing with a narrowband sensor and gauge.

The readings of the gauge will vary for a given load....have you noticed that you get an oscilation while cruising? the gauge will head rich/lean/rich/lean etc.?

Anyways......the *basic* answer, is yes. If the gauge is reading lean, then the sensor is picking up a condition of about 14.7:1 or higher. The drawback to the narrowband is it only sees +/- 0.3 AFR approximately. Meaning rich on the gauge will be 14.4:1 or richer, and lean will be 14.7:1 or leaner.

Closed loop is a function used for cruising at light loads and idling. Since you can run the engine stoich at that load (although not quite stoich at idle), the computer uses the sensor to adjust the fuel to a stoich level during a cruise condition (constant RPM for a given time and a given throttle percentage) to save gas.

 

Yes, for years, in every RX-7 I've owned or have built.

Years ago I tuned my original turbo-NA setup using only a narrowband A/F gauge (AutoMeter Phantom if I remember correctly). Just recently I broke in an tuned my current setup (before the big turbo) using only the narrowband O2 sensor. When I hooked up the wideband after the big turbo upgrade and started the car, it idled at about 13.5 and cruised in the high 13s. Not bad for a "useless" sensor.

Like any other gauge, the narrowband is only useful if you know how to interpret it. I'm not saying that you should run out and do a full tune on your car using only a narrowband, but I am saying that it's far from useless.

For most people, an EGT gauge is just another moving needle. Doesn't mean it's useless. Look at how many people freak out at the needle movement on an aftermarket temp gauge (as compared to the highly dampened stock unit) because they don't know how to interpret it.

 

Tuning with a narrow band AFR is a little like driving toward a cliff at night.
If you're careful, you can do it.
I'm a cheapskate so I did it with the CAS retarded, half a tank of 93 octane and two shots of octane booster.
The car had a rewired 255LPH pump, 720 secondaries, and an S-AFCII.
The S-AFC was wired to sense boost (not TPS) which gives more headroom.
I charted the set points for 14/1, then pushed up the adjustment settings.
After it was all set I reset the CAS, filled up the tank & had no worries.

(Until 6 months later when that fum ducker pulled out & stopped in my lane)

 

How do I interpret lights? I have no numbers or anything on the gauge.

Here is a pic.

Alos, is it really important that I rewire my fuel pump....I've been reading a lot of threads and I think I'm getting paranoid.

 

That point indicates 14.7-.6
The low end of the stoich lights indicate 14.7-.8
The low of lean should be ~15.5
The high end of rich should be ~13.5-14

That's why it's called a narrow band..

 

It's useless for tuning,maybe for a gross diagnostic role it's of some use.Considering you have quit a bit invested in your car by the looks of it,pony up and buy a wideband.You can pic up a innovate LC-1 for under $200 bones before shipping.You can then reprogram one of the analog outputs to use that autometer narrowband gauge to give you a meaningfull light show.Just my 2 cents

 

It's not useful to you because you don't know how to use it. As you have seen from the various posts in this thread, most people do not know how to use it, so don't feel bad. If you would like to know how to use it, then you can take a class at your local trade school or find a local tuner and see if he/she can spend some time showing you how to use it. I do not think it is possible to explain the proper use and tuning procedure on an internet forum.

A wideband kit is a little easier for a novice to use, but I still think you would be wasting your money on one without additional education. I have seen many engines that were supposedly "tuned" by a novice with a wideband, and trust me, they are almost always NOT tuned properly. I would bet money that the forum members who have told you that a narrowband is worthless do not know how to use a wideband either, although they may think differently.

I would not recommend an EGT gauge to a novice, either.

Take the car to a qualified mechanic if you think something is wrong.