How accurate are Air/fuel gauges?

[nandalora]

I just installed an Autometer air-fuel gauge and hooked it up to my front, top o2 sensor. It says I'm always lean, the gauge never moves into stoich. Is it right? I was told by ADC that I may be pushing the limits of my SVT injectors (210-215fwhp they said). I want to get the car dyno'd soon so I can see for myself. Maybe they can even add some fuel to prevent me from having to buy bigger injectors?

Thanks,
Nick

[DemonSVT]

A/F gauges are nothing more then a fancy Blinky Light Show. At best it could be a late warning device for a boosted engine telling you that "oops" you ran lean and now your engine is likely damaged.

Unless you have a wideband O2 sensor you will go no real usable information. Narrowband O2 sensors are not accurate at all. They can tell you stoich pretty well and that's about it.


Also 19lb injectors will support more the 215FWHP and I also do not think they are your problem.


With that said the A/F gauge should rapidly swing back and forth from rich to lean under any moderate load or below condition. It sounds like you have it hooked up incorrectly.

[RodneyBur]

I found some good sites last time I was looking at installing one. Plenty of places will modify your used one to increase the accuracy and change the conditions. Here a couple good sites.


Modified (http://www.boostcontroller.com/index.php?category=11)

wideband (http://www.airfuelmeter.com/french/) <---check out there link pages.

Modifies used ones .... sounds good. (http://www.gadgetseller.com/gauges/modifiedproducts.htm)

[DemonSVT]

Originally posted by: RodneyBur
I found some good sites last time I was looking at installing one. Plenty of places will modify your used one to increase the accuracy and change the conditions. Here a couple good sites.
What they fail to mention is you are still using the same inaccurate narrowband sensor.

The best A/F gauge for a narrowband O2 would be a simple volt meter. It's still not accurate though because all of it's data is from a narrowband sensor.

Narrowband sensors are only accurate right near stoich. (~14.7)
Once you get even a few tenths away from stoich their accuracy goes out the window. Not only their accuracy but their consistency as well. The further away the exponentially worse both get.

[nandalora]

Originally posted by: DemonSVT
A/F gauges are nothing more then a fancy Blinky Light Show. With that said the A/F gauge should rapidly swing back and forth from rich to lean under any moderate load or below condition. It sounds like you have it hooked up incorrectly.

Well I thought I hooked it up right? I hooked it to the top front o2 sensor, on the output signal wire on the connector that plugs into the sensor. Should I have used a different sensor?

Thanks,
Nick

[CougarGT]

Originally posted by: nandalora

Originally posted by: DemonSVT
A/F gauges are nothing more then a fancy Blinky Light Show. With that said the A/F gauge should rapidly swing back and forth from rich to lean under any moderate load or below condition. It sounds like you have it hooked up incorrectly.

Well I thought I hooked it up right? I hooked it to the top front o2 sensor, on the output signal wire on the connector that plugs into the sensor. Should I have used a different sensor?

Thanks,
Nick

A stock narrowband sensor is just that, narrowband. It doesnt matter how fancy the device reading the o2's signal is, its still a narrowband signal.

[nandalora]

So are guys telling me I shouldn't worry about my possibly lean situation? Cause I wouldn't want to damage anything. I guess the only way to know for sure is to dyno, I'll get that done in the next couple weeks. I'm just worried to push the car unless I know everything is running well.

Thanks,
Nick

[CougarGT]

Originally posted by: nandalora
So are guys telling me I shouldn't worry about my possibly lean situation? Cause I wouldn't want to damage anything. I guess the only way to know for sure is to dyno, I'll get that done in the next couple weeks. I'm just worried to push the car unless I know everything is running well.

Thanks,
Nick

Or get a wideband o2.

[nandalora]

So I could get a wide band o2 and use it just for the air to fuel gauge? I couldn't plug it into any of my factory sensor plugs right?

Thanks,
Nick

[DemonSVT]

Some widebands come with a gauge style output. Most of those are just gauges though. Pass on those!
Some come with a digital display in their control box.
Some come with no real display at all.

Only a couple widebands can simulate a 1 volt output for the stock harness. A setup like that could run your blinky light but it's still not giving you any good information because it's just colored lights and not actual A/F numbers.


The LM-1 is pretty much the best setup you can get because of it's 100% custom programmable inputs and outputs. Nothing can match that. Zeitronix makes a decent looking setup. It has a very nice display unit but is IMO limited by just a few preset inputs. Either setup is good though, don't get me wrong. Both use the $40 replacement wideband O2. Several kits use the older $200 one. No it's not more accurate just more expensive now that the $40 is OEM on several newer car. (Supply and demand)

[nandalora]

Well I pulled out several of the o2 sensors, thinking they were fouled and sending a poor signal. But I noticed they were a light brown color, like tan! I've never seen anything in the exhaust path that color unless the engine was running lean. They should be dark black. So I'm pretty sure it's running lean. Anyway I'm gonna go dyno tune on Tuesday and have them reflash my chip. But, do you guys think it may be worth while to try running the car without the chip in it to see if it runs better, maybe ADC screwed up?

Thanks,
Nick

[Kinger]

Check your plug color and determine rich lean from that. Post a pict if you need help. O2's should be brown not black.

[fordrule]

would u recomend using the a/f gauge with a wideband 02 sensor.

[DemonSVT]

Originally posted by: fordrule
would u recomend using the a/f gauge with a wideband 02 sensor.
No, not even if the wideband controller had a programmable output to support a narrowband A/F gauge. (A wideband sensor requires a controller and heat pump btw)

The blinky lights will always be worthless because they give no actual numbers.