I got a 2000 Z28 basket case and have been busting my *** to bring it back to its former glory as a Mustang killer. I just replaced the Tranny, brakes, rack and pinion, installed LS6 intake and 3" exhaust kit. The car had headers when I got it and had been tuned previously. It has rear O2's which I know need to be turned off. It has had the check engine light on since I got it and the upstream passenger O2 has unhooked since purchase. When I hook it up the engine smells like it's burning rich and starts idling rough and even accelerates roughly. I know I need another tune and have been considering sending to Frost, but will this fix my rich, rough idle/acceleration issue or do I need a new O2? I have worked hard to this point and I've learned so much about LS engines from this site. Any help is very appreciated!

 

Fix the O2 first.

 

So the O2 being unhooked means its bad for sure?

 

Depending on the duration of time the 02 has been unhooked it's probably dead. Oxygen sensors need to be able to warm themselves up to stay alive under all the conditions that go on inside an exhaust pipe.

Replace the 02, and have someone with a scanner confirm both 02's are working. Unless someone tunes the car to stay in open loop, you will need both upstream sensors fully functioning at all times to achieve the best driveability. They're a key player in what the PCM uses for part throttle fueling correction, IE: driveability.

 

Thanks! I'll grab new O2's today and change the plugs as well. The car was like this when I got it and I've fixed all the other issues so this is one of my last obstacles. You can't beat the bang for the buck these cars offer.

 

Try the right forum....