fna7302

I have a 2002 T/A with a new LS6 engine out of a 2004 ZO6. Car has AR long tube headers. Car is running in closed loop and seldomly switches over to Open Loop. P0155 comes up after driving for about 25-30 miles-all sensors are new and wiring has been tested and is fine. Cooling system is working normally. Freeze frame data shows norm fuel trims and o2 sensor operation. The exhaust has multiple pin hole leaks downstream of the last o2 sensor starting at about 2 feet after the Bank 2 sensors. The leaks are from band clamp type clamps. The car was tuned in the Spring and misfires/pops out the exhaust during cold weather (I live in New England-not sure this has anything to do with the oxygen sensor issue). I don't know what else to do at this point...hoping someone can help...feel free to email me at map333@***.net or text/call at 4014872333...thank you in advance.