I have been toying with getting an air/fuel meter to install along with my S/C but I'm wondering how much they actually cost. I see the AEM one is around $350 while others are only around $50.. Are any better than others? Do they come with the sensors?

 

The cheap ones are "narrow band" and don't give you any numbers, just a bunch of flashing lights. These don't give a true indication of what your a/f is, but rather, an approximation of a relative range. These will give you an "idea" of what's going on. These tap into the primary O2 sensor that's already on the car.
If you want a gauge that will give you actual numbers, the AEM type is what to get. This one has both numbers and the moving light scale. It comes with it's own O2 sensor which you must install into your header. You may have to have a hole and bung installed to put this sensor in unless you have an aftermarket header that comes with a second bung.
I have had both. Here is a thread showing my transition from narrow band to wide band:

https://www.s2ki.com/forums/index.ph...&f=71&t=267255

 

I have the AEM gauge. It works well, but replacement sensors can get costly at about $100.

I tuned my car myself with just the AEM wideband with great success.

 

Thank you! That is exactly what I was looking for! That AEM is really nice but it is not in my budget right now. I understand the cheap ones don't give you numbers so how do you estimate what your A/F is? Does each guage have scale almost like a speedometer?

 

It has a gauge like a clap meter on tv. It is kinda rich, kinda ok, kinda lean. That is about as good as a narrow gets. The rule of thumb I used was if it is out of the rich part then it is bad. Well my car stock ran in the middle of the rich on an Autometer gauge but I used that kind of reference for my eclipse.


L8R

 

If you're going to get a narrow band borrow someone's wideband and see how accurate it is by running them both at the same time using the wideband as a point of reference.

 

First of all, having had both, I can tell you that the accuracy is not great on the narrow band. The lights flash by so quickly and jump around so much that the only time you can actually see a distinct reading is when you are at WOT and getting near the top 1/2 of the rpm range. There, it stabilizes somewhat and you can pinpoint which light is on. In the manual that comes with the gauge, it tells you the volts (millivolts) that each light represents. Then, there is a graph that converts these volts to an a/f number. You will see very quickly that the graph is very hard to interpret because of its slope and "narrowness". (I guess that's why it's call a "narrow-band"? )
I used this gauge for over a year before I got my AEM. If you are meticulous about reading the lights and are very accurate with the graph interpretation, you can get a "fairly" decent idea of the a/f at WOT in the upper rpm range. I did not use this gauge for tuning. It was purely for curiosity.
CAUTION: If you are using this type of gauge, you MUST also utilize other means to determine the running condition of your engine (like reading the spark plugs periodically and getting a "sense" of the sound and feel of how the car is running). To use ONLY this gauge as your guide would be quite foolish.

 

Thanx again xviper. I wasn't planning on doing any tuning whatsoever with it. I was just wanting a warning sign if anything became "off." So, from what I gather, narrowband will take a little too much interpretation to be an actual warning indicator.

 

Not necessarily. For what you want to use it for, it'll be OK. Just back it up with reading your plugs from time to time. Like I said, you are mostly concerned about what the a/f is under load and this happens at WOT in the upper rev range. In these conditions, the blinky lights do stabilize enough for you to know that it is in the necessary "rich" area.