Just like it says, "Is there any way to make a cel go out while running a "test pipe"?" It pops a "Catalyst system Efficiency Below Threshold" (Code 70).... Is there anyway to make it go out without putting the "cat" back on?

 

Yes try a search You could use a 02 sim or try the tin foil trick!


edit: Are you using an OBD1 set up?

 

No OBD1 set-up

 

Try wrapping your second o2 sensor in tin foil. Thats what I've read about jeep guys doing