Knowing that it doesn't have impulse fault codes saves me a lot of time looking for connectors that don't exist. So I've worked with the on/off ratio and this time I used a dwell meter (in the absence of a DVM with duty setting) and I see the same thing I observed with my oscilloscope. I get 40% for about a minute and it steadly decerases to 0% over aproximately 30 seconds. Now what I read in the service manuals tells me that Lamda should be aproximately 50% after warmup. I'm thinking of replacing the O2 sensor and trying it again. Can you suggest additional or an alternate course of action? I never stated the reason I'm running these checks, which is hesitation on part throttle acceleration from idle. Additionally, the spark plugs are white which indicates lean mixture. Full throttle acceleration is OK.