02 sensor help

[mikemounlio]

My good friend has just bought a new to him TJ. It has the 2.5 in it. The jeep came with the cat taken out and a straight pipe inplace. The 2nd 02 sensor was not hooked up. Aside from cutting a hole and welding on a flange what can he do to get the 2nd 02 to function? Is there anything that can be done?

 

[BUG-E J]

If you leave the cat gutted the downstream 02 aint gonna do much anyway. :****:

 

[mikemounlio]

I found you can make a simple bypass to make the sensor read a steady number and it gets rid of the cel. Just didnt know if anyone here had any other ideas.

 

[pholmann]

Do the bypass. You would be amazed at how much your downstream O2 sensors have to do with your fuel trim, even though the manufacture doesn't claim it does. Weld an extension tube thats a couple inches long to the exhaust pipe with the bung welded into the end and it should cut the cel off.

 

[mikemounlio]

If he does the bypass (little circuit board trick) would he still need to have the 02 sensor mounted in the exhaust? I thought it was a deal where you wire up the circuit and just zip tie the 02 up somehow. The circuit broad would then just send the signal like normal. Meaning you dont need to drill a hole weld on the flange and mount the sensor.

 

[Shortbus]

Do the bypass. You would be amazed at how much your downstream O2 sensors have to do with your fuel trim, even though the manufacture doesn't claim it does. Weld an extension tube thats a couple inches long to the exhaust pipe with the bung welded into the end and it should cut the cel off.

This^^ The downstream O2 sensors do more than most realize. I'd do what was recommended about making an extension . You also can stack a few modified defoulers but the welded tube is easier. You still want the sensor to read something from exhaust. A constant reading can throw a non responsive sensor code as the system thinks sensor is bad. Sometimes you have to play with the tube length so you'll read some exhaust and not get same reading as your front sensor.

If he does the bypass (little circuit board trick) would he still need to have the 02 sensor mounted in the exhaust? I thought it was a deal where you wire up the circuit and just zip tie the 02 up somehow. The circuit broad would then just send the signal like normal. Meaning you dont need to drill a hole weld on the flange and mount the sensor.

There is a circuit board trick to "modify" the output from O2. This would just take real reading and reduce what system sees. I've neverdone it this way.

 

[mikemounlio]

I know he could add an extension to get the 02 out of the straight pipe and that can read the right amount to make it work half way right. The circut board idea is just a cheap quick fix while he has time to get the other method done. We will give the quick fix a try and if it doesnt work then he will have to find time to fix it right.