[ctrlz]

Originally Posted by cjperformance

After reading up on this, i grudgingly had to admit that installing post cat for tuning can be done too.... HOWEVER....

great honest opinion.
I think we can see how this "might" work.
OP obviously already has a lot of problems with the post-cat install. is that because of fouling, bad sensor, something else?
Given this scenario, I would install a new sensor pre-cat and start over.

[2k2ss]

It does work he has tuned hundreds of cars this way

[2k2ss]

Hmm I didn’t mention that its a E85 tune! I don’t know if that makes a difference or not but wanted to make it known

[Briland_1LE]

You can find out for yourself with a quick google search why you wouldn't want to mount the O2 behind the catalytic converter. NOx is converted to oxygen and nitrogen, therefore you will get a reading of higher oxygen content than you should be. You will have your tune be a little richer than it should be.

"During the first catalyst stage (the reduction catalyst), nitrogen oxides react with a platinum and rhodium coated honeycomb structure. When these harmful nitrogen oxides react with the catalysts (platinum and rhodium), the catalysts remove the nitrogen molecule, hold onto it, and release the oxygen molecules."

[Classic Muscle]

Here's one being installed post cat. Maybe cats are gutted? This is CA though, Not going to pass smog check like that.

[ctrlz]

Originally Posted by Briland_1LE

You can find out for yourself with a quick google search why you wouldn't want to mount the O2 behind the catalytic converter.

I think, apart from the OP, we have agreement on this.
OP has problems, but also has full confidence in his tuner.

If problems persist, I would suggest opening a new thread in the tuning section of this forum. Perhaps some of our experienced tuners have dealt with the post-cat data problem.

[6spdhyperblue]

Did you perform a free air calibration?

[KingLT1]

Originally Posted by 2k2ss

Hmm I didn’t mention that its a E85 tune! I don’t know if that makes a difference or not but wanted to make it known

I have been running E85 for 5yrs with the same wideband sensor.

[2k2ss]

No I don’t have problems! I bought a new sensor and it works perfectly! Just like the tuner said!

[2k2ss]

Originally Posted by 6spdhyperblue

Did you perform a free air calibration?

Yes on the first one and now on the second new sensor. The new sensor I got today is working perfect.But thanks for the suggestion!!

[laynlo15]

Originally Posted by 2k2ss

Yes on the first one and now on the second new sensor. The new sensor I got today is working perfect.But thanks for the suggestion!!

Sensors fail, your did and as you bought another that fixed it you can move on and have fun with your ride. Exactly what I said in my post about my old C7. I have my current 02 between the stock cats. Works perfectly fine.

[JSH]

Originally Posted by 2k2ss

i just installed a brand new aem wideband kit . i installed it in the driverside rear 02 sensor factory bung. from the beginning it seemed to jump all over the place and then it stops showing areading and just show lines then starts working again. is that sign of bad sensor.whats the best brand to replace it with?

I installed AEM's X-Series OBDII Wideband before the cats. No issues.