the roadie said:WELCOME COMRADE!!!!! I'm a EE, and have been volunteering on trailvoy, then GMTN, for 7 years now, and you're the first poster to ever show scope shots!!!!! You probably don't need to have the term PWM explained, either.
Those are horribly slow transitions. O2 sensors should run at 1 Hz or faster. When I put in a new one, it was about 1.5 Hz if I remember correctly. If you have a new sensor, then something else is slowing down the control loop. A dirty throttle body would give you an erratic idle as the AC compressor cycles on and off, and you would probably have mentioned that. But depending on your mileage, it may be a good thing to do anyway. Many of us do it every 30K.
But the throttle plate isn't involved in the quick transitions, I don't think. Probably fuel injector pulse width and duty cycle. My experience is that it's usually a bad O2 sensor, but if your Delco is new, I'd start by looking at the Fuel Trim numbers to see if you have an injector issue (could benefit by running injector cleaner and/or a Seafoam treatment) or a vacuum leak. Loose hoses and especially loose intake manifold bolts are a common problem.
How did you find us, by the way, after we all left Trailvoy last December?
would you mind me asking about the reason for the exodus from the trailvoy site?
umm nevermind that question. along with the welcome message and using both sites for a little while now- it is obvious this site is superior- better info and easier to use.