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Old 09-03-2007, 03:55 PM   #1
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Default a/f gauge help

ok i have a a/f gauge im trying to hook up and i need to know which wire i hook it up to im lost
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Old 09-04-2007, 11:25 AM   #2
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I'll check and see if I can get you some help.
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Old 09-04-2007, 12:10 PM   #3
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The purple wire.

But I'd like to mention also that it'* a waste of time. A narrow-band O2 and AFR gauge won't do you any good other than dressing up the cockpit. Zero benefit.
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Old 09-04-2007, 04:54 PM   #4
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Quote:
Originally Posted by willwren
The purple wire.

But I'd like to mention also that it'* a waste of time. A narrow-band O2 and AFR gauge won't do you any good other than dressing up the cockpit. Zero benefit.
Could you please explain why this won't do any good for those of us that don't know why. Otherwise, this just seems like a personal opinion and might lead someone astray...
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Old 09-04-2007, 05:11 PM   #5
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From another old thread...

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Originally Posted by willwren
...Narrow band is the bare minimum the PCM needs to set AFR. If you're out of that very narrow band, you have no idea what the car is doing.
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Old 09-04-2007, 05:13 PM   #6
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Quote:
Originally Posted by lash
From another old thread...

Quote:
Originally Posted by willwren
...Narrow band is the bare minimum the PCM needs to set AFR. If you're out of that very narrow band, you have no idea what the car is doing.
Thanks. This makes sense now.
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Old 09-04-2007, 05:17 PM   #7
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Quote:
The narow band O2 is essentially that, it has a very narrow band of which it reads accurately. In fact, that range is so small it'* almost just a switch and can essentially be thought of that way. While not getting into detail about the inner workings of engine management systems, the narrow band O2 essentially tells the ECU either to add fuel or take away fuel depending on which side of the switch it'* on. Just where does that switch point happen to be, well, it'* at the 14.7:1 as mentioned above. While this does a good job of telling you if your car is running rich or lean, it doesn't accurately tell you how rich or how lean.

This is where the wideband O2 steps into the picture. It has a broad range of measurement and can accurately tell you where you are sitting air-fuel wise. Why is this such a good thing, well, in order for a car to make good, safe power you want to run it a little on the rich side of things. For example a typical turbo car will operate best running at an air-fuel ratio of approximately 12.3:1. On the narrowband O2 you'd have a hard time finding this point, but with use of a wideband O2 you can accurately read where you are. It'* the best way to get air-fuel ratios sorted out and you'd be surprised at the difference in power a properly tuned motor will have.
An AFR gauge coupled with the OEM narrow-band O2 sensor is nothing but pretty lights. If you want pretty lights, by all means go for it. But if you're going to bet your motor on it or derive some sort of tuning info from it, forget it. A fake boost gauge would do you better.
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Old 09-04-2007, 05:23 PM   #8
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Now THAT really explains it, IMO.

I hope that we haven't taken Aaron'* question too far off topic, but I know it has helped explain this to some.
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Old 09-04-2007, 05:26 PM   #9
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The off-topic was intentional on my part. I'd rather see someone spend their money on something useful. Alot of people misunderstand the aftermarket AFR gauges. And especially in a boosted application, this gauge can give a false sense of security, no useful data, and a potentially blown motor from data that it can't provide.

In order to determine proper tuning of AF curves or fuel pressure/injector selection, you MUST have wideband O2 data.
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