[dgc333]

I have continously owned at least one turbo mopar since 1985. All of the cars I added one of the LED A/F guages that bounce as you say. The real use of these is when you make modifications. The bouncing is caused by the closed loop feedback control of the engine management system. Whether you have a wide band or narrow band O2 sensor you will get this bouncing of the signal because the ECM is constantly changing the mixture.

At Wide Open Throttle (WOT) the engine mangement system goes into open loop operation and looks at parameters in a look up table and based on the values will set the duty cycle of the fuel injectors. When you start changing boost or modifing the exhaust/intake the ECM does not know this and you could get into a dangerous lean condition. It is under these conditions that the LED A/F guages give you and indication that you are running rich enough to prevent damage. With the 2.2 turbo mopar engines it is generally excepted that 9 of the ten LEDs lit is good under WOT.