How to wire air/fuel ratio

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Amfo
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How to wire air/fuel ratio

Post by Amfo » Thu Apr 07, 2016 1:38 pm

Hey guys, is it possible to wire in an auto meter air fuel ratio gauge in my car? Running an 8ua ECU.
1969 Impala SS 427 Small block (Dart motor)
1987 XR4ti 5 speed

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merkurdriver
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Re: How to wire air/fuel ratio

Post by merkurdriver » Thu Apr 07, 2016 2:19 pm

Yes, really easy. 3 wires, one is 12v+ power, one is ground, and the third one you can splice into the oxygen sensor wire.

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Grayson
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Re: How to wire air/fuel ratio

Post by Grayson » Thu Apr 07, 2016 2:20 pm

I would recommend logging wideband O2 readouts rather than using a gauge of any sort. Given how I've worked with my datalogs, I'm not sure how a gauge could provide much value. There's no way I could remember what the peak O2 reading was, and what RPM I was at, and of course, I really wouldn't have any idea what the load on the engine was.

It's kinda like being able to read the temperature of your oven, but you don't know how long the turkey has been in there, and you have no idea how big the turkey is.

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Re: How to wire air/fuel ratio

Post by GPz11 » Thu Apr 07, 2016 2:32 pm

Also make sure you get a wideband gauge, not a narrow band.

I used mine just to make sure I wasn't running lean under boost.

Amfo
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Re: How to wire air/fuel ratio

Post by Amfo » Thu Apr 14, 2016 12:58 am

So. I hooked it up and I didn't get any sort of read on the gauge and the car ran and idled like crap. I disconnected the gauge and it runs fine again. As its only three wires I didn't screw up wiring it-but I double checked and it's good. This is a single wire stock o2 sensor I have. Any reason as to why hooking up the gauge made it run rough?
1969 Impala SS 427 Small block (Dart motor)
1987 XR4ti 5 speed

thesameguy
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Re: How to wire air/fuel ratio

Post by thesameguy » Thu Apr 14, 2016 2:21 am

Welll..... most likely because you hooked it up wrong or made bad connections. :D

It's *conceivable* though unlikely you have bad wiring somewhere else in the car, or maybe, possibly, a bad O2 sensor but in both cases the issue being insufficient amperage to drive both the computer and the gauge, but man, that seems like a stretch - it just doesn't take much to drive an AFR gauge. Or, I guess, a bad gauge. :)

If you have a digital multimeter, probe the O2 sensor connector *while it's still connected to the ECM* on VDC and watch for readings between 0v and 1v. If your multimeter can't get a reading, or if connecting it *also* kills the car, you have one of those stretchy explanations.

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