[Thirteen8teen]

The cats were stolen from this truck while the previous owner had it. I grabbed a couple of flanges for the manifolds from the junk yard and I’m just going to run a straight pipe from the manifolds to the muffler. Only question is…what to do about the O2 sensors? There are 2 in each side, right? Shops here don’t want to touch it with no cats, so we are just going to get the pipes bent and put them in ourselves. How should I handle the o2 sensors to make everything work like it should? Thanks!

 

[DigEm]

Easiest fix is to have the after cat, downstream, ones tuned out. Otherwise you have to figure a way to trick them into reading correctly. That is accomplished by using spark plug non-fowlers so the heat readings stay within parameters. Like this...

How To: Install An O2 Sensor Non Fouler to Eliminate a...

Disclaimer The community here at 355nation.net urges you to please use caution and seek professional assistance when performing modifications to your vehicle. Before attempting any modification it is advised that you refer to your Colorado or Canyon service manual or contact a certified mechanic...

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You just have to do one each side for the V8.

 

[cart7881]

Obviously you aren't going to make everything "work like it should" without the O2 Sensors. You might fudge the system when it comes to the downstream sensors, but what will you do about the upstream sensors? Not sure how you can get the ECM to operate indefinitely in open loop mode. Once the ECM sees certain parameters it will want to switch to closed loop and then the upstream O2 sensor will be necessary.

I don't think anyone has any experience with running without any O2 sensors. Maybe just connect the exhaust as you plan to do and see what happens.

 

[DigEm]

Obviously you aren't going to make everything "work like it should" without the O2 Sensors. You might fudge the system when it comes to the downstream sensors, but what will you do about the upstream sensors? Not sure how you can get the ECM to operate indefinitely in open loop mode. Once the ECM sees certain parameters it will want to switch to closed loop and then the upstream O2 sensor will be necessary.

I don't think anyone has any experience with running without any O2 sensors. Maybe just connect the exhaust as you plan to do and see what happens.

I am only suggesting he make the seconds be fooled, or have them tuned out. I am not suggesting he dio anything with the upstream o2's. You need those.

 

[cart7881]

Yeah, I assumed that you were referrring to the downstream cats. The upstream sensor is before the cats so he might get away with welding a bung in the pipe just aft of the flange and installing a sensor there. The OP didn't mention how the cats were removed. Don't know if the pipe was cut or the flange nuts removed. If the pipe was cut, the upstream sensor may still be in place.