I bought a Prosport Performance Series Air/Fuel ratio gauge. I don't currently have a wideband sensor (I'm waiting for my ypipe to come so I can weld a bung and do it the right way). In the mean time I've been trying to tap it into the stock o2 sensor so that it at least works. However I've ran across a problem getting it to work properly.

The gauge is an analog stepper motor gauge. I've wired the power to a 12volt source in the fuse panel and the ground to the same ground as my aftermarket head unit stereo.The sensor wire I have tapped into pin 50 from the ECU which should be the signal wire to the front o2 sensor.

Here is where I run into problems. The car is running at idle and heated to appropriate temp: If I touch the tapped in signal wire directly to the signal wire on the gauge it jumps to full rich and does not fluctuate. However, If I hold the tapped wire in my right hand and the gauge wire in my left hand (acting as a human bridge) the gauge will read just above lean and when I rev the engine the gauge will fluctuate appropriately based on how much gas I give it.

So the question is: What is causing it to jump to full rich if I don't act as a bridge? Does this mean I have a bad ground? Or the signal from the ECU is to strong? Anyone have any idea?

 

I'm pretty sure you can't use the stock O2's to read AFR.

 

Your stock 02's are narrowband not wideband

 

You can use a narrowband stock o2. You just won't get an accurate reading from it as you would a wideband.

 

Yeah, you're obviously not getting an accurate reading.

This is probably the range where yours is reading so it seems super rich:


As opposed to the range you'd be able to read with a wideband:

 

This is true
Even narrowband gauges usually provide you with their own narrowband O2 sensor...they don't expect you to tap into and use an OEM narrowband O2 sensor.

Besides, your wideband gauge is expecting wideband readings. I think the fact that you're mixing apples and oranges is your problem. I wouldn't sweat it. Just wait until you got your bung installed and do things right.

Wideband gauges are sometimes picky. They should have their own ground, not shared. And make sure you really got bare metal...scrape that paint away.

 

I'm not going to mess with the narrowband anymore. I pretty much gave up after tonight. The gauge will just have to sit on my dash glowing all pretty until I get the wideband. I'll also look into feeding a ground to the engine bay and grounding it to the block so I know I get a good solid ground.

 

infinimax did you ever figure it out? i got my gauge and wideband but i cant fnd he wiring diamgram for the life of me, my sensor has 6 plug connection did i get the ight one?

 

Don't think you needed the 6 plug sensor. Should only need 4. 2 go to power, 1 goes to ground and the 4th is the signal wire that goes to the gauge. I didn't figure mine out yet because I've yet to put in a wideband.