How are you bypassing the front o2 sensor? its need to actually measure the gases so the computer is tuning properly? I guess it depends on your exhuast setup...I know just gutting the cat will usually result in a bit of low end power loss...

 

You NEED the pre-cat O2 sensor, as that is the one that most regulates fuel mixture ratio when the engine is in closed loop. I do believe it actually starts to make a difference within a couple minutes of startup. (cold motor. sooner on a warmed motor.) Post cat O2 DOES have some influence over mixture...... and not having a cat will tend to cause that one some trouble. Doing the non-fouler trick should solve that issue.

 

I thought the same thing then I decided to have the cat removed and at the muffler shop they took the one inside the cat out. Unless they wired the wires of the front sensor to the back sensor (I dont even know if thats possible) or relocated it, it's been bypassed

 

Huh? Splain Lucy,

 

If the catalytic converter is out, then usually the mixture goes real rich. Am I right?

 

Mixture is controlled by the pre-cat O2. It doesn't care if the cat is there or not. If the PCM sees the same signals from the post cat O2, as the front, then it will tend to richen the mixture to warm up the cat, to make it work better. If it isn't there..... it ain't ever gonna work better.... so, you always run a bit rich. Putting the non-foulers on the rear sensor fools the PCM into thinking the cat is still there, and working correctly. No codes, better fuel economy, no false rich condition.

 

That makes me wonder why I only have one o2 sensor now

 

Probably when they took out the cat, they didn't put something back.....

 

Where is that one sensor located?

 

Bout a foot infront of the glasspack