I've heard buying anything but a crazy expensive air fuel gauge is worthless, because they give crappy readouts. Is this true? If not, whats the best affordable one that can give decent readings?

 

A guage is only as good as its sensor which is where it gets information from. Given our stock O2 sensors are narrow band units they aren't very good for tunning as they only read, as the name hints, a narrow band of Air to fuel ratios because they are meant to optimize fuel ratio's(fuel economy increases) at cruise and low throttle. If you want your own tuning device look for DIY Wide band kits or pre-made kits. These can go for as little as 350 dollars.



Santiago


PS- I had a thread about widebands and engine management systems a while ago. I'll find the link.

 

Well for tuning i'll probably be taking it somewhere to dyno tune it with a wideband, but I was just thinking something along the lines of telling me if something is way out of wack.

 

Well from what I understand about the stock sensor it only goes into its accurate range while cruising at low throttle to optimize "highway mileage"



Santiago


IF this is wrong please correct.

 

http://www.innovatemotorsports.com

Cheapest wideband I've seen available.

 

I am however going for the more expensive option at hand, the LTX12's wideband feature.


Santiago

 

That's the best use for A/F gauges on the stock sensor. You learn the pattern of its readings under varying driving conditions and then you notice if that changes.

Most people appear to have no clue about that.

 

All of the people who don't know how to tune an engine will tell you that you must have a wideband O2 sensor. While this is a good tool, it is not going to instantly make a novice into a pro. If you just want to monitor the engine, or if you are interested in fuel economy, a narrowband O2 sensor will work just fine. The wideband is better for tuning for power because it registers the richer "best power" air-fuel ratios more accurately. However, some of the better tuners that I know don't even use a wideband sensor.

A narrow band sensor is most accurate near the stoich (chemically correct) air-fuel ratio, and it gets less accurate as the scale gets more rich or lean from this point. Also, heat will affect the sensor's output.

Modern engine control units and O2 sensors are not able to react fast enough for rapidly changing engine conditions, so the O2 sensor is only used to control fuel delivery at more steady-state conditions. This works out well because the best economy air-fuel ratio is usually pretty close to the stoich mixture. The engine control unit ignores the O2 reading during changing engine conditions, such as acceleration and deceleration.

 

The idea of trends is totally foreign to today's wanna-be engine tuners. It seems that they want to plug one magic number into the EMS and instantly have the best performance and economy possible. I don't know where they get this from, but I find it disturbing.

 

I understand that a wideband isn't needed for tunning. I have talked to REted and he only uses an EGT guage out on the road for tunning. But I usually tell people to just use a wide band because it makes it less easy to mess up. Its like trying to perform a delicate operation with beer gogles(narrow band) compared to proper perscription glasses(wideband). I guess I also didn't word my explenation of narrowband correctly. :/ I need to work on those skills. But From what I had read on the tech edge site your right on the money. The narrow band only becomes accurate where it counts for econommy of fuel consumption.


Santiago

PS- I'm still learnin cut me some slack. :-/

 

... and if you took that EGT gauge away from RETed, he would still be able to tune the engine. I guess that's my main point about AFR gauges, EGT gauges, or any other tool.

Yes, but you can still use it for tuning the richer AFR's if you understand the nature of the errors. This goes back to what NZConvertible stated about trends.

I was expanding on your statement, not correcting it. You are doing fine.

 

No arguement there. Ted is my number one teacher followed closely by Brian and You and NZ. I still love this forum.


Santiago

 

^^ informative

 

Damn, I didn't even know I was being talked about.

Back to the original question...

The AFR gauge is the best gauge to show you if you're too rich or too lean.  Do not use this for fine tuning, as it doesn't have the resolution to give you accurate and repeatable results.  I recommend the AFR gauge because it's the fastest reacting gauge (for the price) that can tell if you're in TROUBLE (too lean)!

A wide-band will do the same thing, but it requires a lot more money and installation of it's own dedicated sensor.

People will disagree with me, but I stant behind my statements.


-Ted

 

I have the tomei 4 wire air/fuel ratio gauge and amp on my car and it seems very accurate under varying conditions.

rgds

 

About all the gauges are the same accuracy, they all do exactly the same thing, they translate a relitively innacurate, varying voltage. This is whether you get it for $28 from summit (Nine LEDs) or a $100 Nordskog (270 degree sweep gauge).

 

hey sorry to dig up anther old thread, but im not getting instructions with my afr, how do you hook it up? how does it hook to the o2 sensor, just twist the wires?

and then after its hooked up, is there any other ways to significantly affect/adjust your a/f ratio other than the screw next to the pressure sensor? (87 gxl)

 

One wire goes to power, one to ground, and one to the O2 wire at the ECU. See attached diagram for connection info.

 

cool

hey thanx with all the noob q's aaron

 

For future reference, please don't dig up old threads, it's just confusing for everyone else. You should've started a new thread, since none of the posts above are needed to answer your questions.

Stay away from the O2 sensor entirely. Hook it up at the ECU as per the pic above. Solder all your connections, don't just twist them together.

That only changes idle mixture, it has no effect anywhere else. Factory EFI is never adjustable, you need to add a fuel controller to do that.