After I installed an air/fuel ratio guage in my Camaro I noticed that the readings would hesitate, and generally swing back and forth a whole lot slower than they should. I figured that meant the O2 sensor was going bad so I got a new one. Since I have headers and am running a cooler thermostat, I got a heated O2 sensor. I wired up the heating leads to power, and plugged in the sensor lead. Now, the air/fuel ratio guage is acting more like a voltmeter, it holds steady and just makes small movements when I turn on the a/c or do something else that also makes the voltmeter move. To add a bit more strangeness to it, every once in a while, if I'm at full throttle for several seconds at least, the guage seems to start reacting as it should. I double checked all air/fuel guage connections, they're all good. Did I get a bad sensor that's letting the heating coil ground through the sensor itself? Any other ideas?

 

What are you expecting out this guage ? The 02 sensor is nothing more than a switch that tells the ECM if the AFR is lower or high than 14:7. It's not gonna give you accurate readings. IMHO the guage is just a nice looking gadget when hooked up to the stock 02 sensor

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92 Z28 L98 350
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Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires.

Best ET 13.5@105 mph

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)

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On an EFI car, the guage should make a fast swing from lean to rich as the O2 sensor detects the rapid mixture changes the ECM is making. If it's staying in one spot, something is wrong.

 

Andy, have you tried unhooking the supply to the oxy sensor's heater, to see if the gauge changes?


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
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I'll probably do that this weekend, I just wanted to get every possible cause before I start so I don't do one thing and then sit there wondering what else it might be. I like to know all possibilities beforehand...

 

Andy, Am I reading this right? You wired two of the leads to power and the third to the sensor circuit? One of those two leads is ground and the other power. Both are the same color, so it matters not which you wire to power or ground.

 

Oops, it does look that way when I re-read it. I did hook it up the right way though, one to power, the other to ground.