I have a '93 LT1 that I swapped into an '89 IROC and am having a rich condition that I just can't figure out. I rebuilt the motor, upgraded to 1.6 roller rockers, LT4 hot cam, port matched heads and intake. When you start the car cold it runs fine, O2 sensors read about 450mv, all other sensor read normal ranges, coolant temp sensor is accurate. As the engine warms up, the left bank O2 climbs gradually up between 650 and 700mv. I have checked intake for leak, exhaust leak, plugs, wires,etc. I can't do a compression check without removing the headers. Both O2 sensors are new and swapping them gives you the same results. Didn't write down the blm's or the short terms. Anyone have any ideas???

 

Is it flippin to closed loop?

 

Yes, it is. I have discovered that I have upgraded so many things that I now need to get the supplies I need to tune the engine with a new eeprom and tuner software. I have read just about everything I can find on the subject and am anxiously awaiting my first try at it. Thanks for the reply.

 

Consider a WB if in your budget.