I have a 95 with a 5.7. the cat is totally gone. Does the O2 sensor need any back pressure to work properly? This trk only has the one sensor on it. And what about back pressure in general? How much do you need? I have the factory Y pipe and the 2 3/4" pipe with a thrush muffler.Is that ok?

Thanks

 

The cat is bad? or just removed? Whats the main thing your after, is it running poorly?

 

He said the Cat is gone... And when I removed my Cat I relocated the O2 sensor back up on the drivers side manifold.

 

So I take it you guys dont have after cat o2's before it was removed? I have 4 but know some earlier models only have 1 or 2

 

The 95s and earlier have one non heated O2 sensor before the cat 96 and later i think have one before the cat and one up on the manifold.

 

Ahhh, I see , I understand now. thanks. I am still curious what the problem is with the inital post in this thread, is it running bad or are you just curious?

 

Well when you remove the cat if you do not relocate the o2 sensor it seems to lack a little power. I think that he was just wondering if he removed his Cat. if it would hurt anything? Just guessing lol.

 

Pre OBD II vehicles do not have A O2 sensor to monitor the cat. O2 sensor do not need back pressure to work. They actually work similar to a battery. As the exhaust gas pass over what is inside of the sensor (iridium, platinum or what ever else they use now) It creates a charge. Depending on the fuel mixture it generates a specific voltage. Now engines do run better with some back pressure, if your trucks engine is basically stock you you probably benefit from at least a high flow cat or minimally a muffler with more substance to it.

 

I see, thanks MDTAHOE, that was news to me. I didnt understand the earlier models.

 

I was told by the Gm dealer that Mine needed to be near the cat for the heat and that was why I had to relocate mine up by the manifold. Is this True?