TBSPW

I have a Autometer Cobalt Narrowband o2 gauge and im not sure why it just bounces all over and when i pin the pedal to the floor it just slams into the rich side...so im just wondering what wire off of which o2 sensor should i have hooked it to...any help is appreciated

TBSPW

hmmm after lookin into it more i think its the purple it has to be connected to...now i have to go check if i did that or not

Injuneer

Sounds like you have it hooked up 100% correctly, and its working exactly the way it should be. Normally, the engine runs in "closed loop" - the PCM constantly dithers the A/F ratio back and forth constantly from slightly above 14.7:1 (lean) to slightly below 14.7:1 (rich). It does that because that is required to make the catalytic converter work. The O2 sensor voltage swings over the range of 1xx-9xx mV's. Your gauge swings back and forth, providing little more than a psychdelic light show, and indicating only that the PCM is correctly in closed loop. The PCM adjusts the injector pulse width using short and long term fuel corrections to keep the average A/F ratio at the stoichiometric value of 14.7:1 - decent gas mileage, and minimun combined emissions of CO, HC and NOx.

When you put the throttle on the floor, the PCM enters "power enrichment" mode. It sets a much richer target A/F ratio, because that's what is require to make more torque and HP. 14.7:1 is good for emissions and fuel mileage, but not very good for power. Typical target A/F ratio in PE mode, with stock tuning is about 11.7:1.... e.g. - "too rich" factory programming. At that A/F ratio, the stock narrow-band sensors are so inaccurate as to be pretty much useless. Again, all you can determine from your narrow-band driven A/F gauge is that the PCM is in PE mode.

The gauge is not really very useful.

TBSPW

thought i was right...i got the gauge from a friend for free anyway