[SentraSE-R]

dcb, read the thread. My kill switch fixed the TCs long ago. Your ECU and TPS tangents ignore the elephant in the room, which is the unlit cat for the previous 800 miles.

I will ask the smog test station about the possibility of a retest, now that I have 900 recent cat-lit miles to clean the cat out. Hopefully they'll do it for less than their full price.

Back to the issue:
I'm reducing my fuel usage to 56% of normal. When the engine is running (let's assume 50% of the time, for a round figure), I'm spewing out 3-15X the average HCs, 3-7X the average NOx, and up to 6X the average CO at a minimum, when the cat is lit. So, if I cut my engine run time and gas usage ~50%, but quintuple my emissions during that time, I'm effectively emitting 2.5 times the pollution of the average car, when my cat is lit.

From my recent history, my cat isn't lit most of the time. If a lit cat is 50% efficient, my emissions through my unlit cat are double what they were during the smog test, when the cat was lit. If a lit cat is 90% efficient, my emissions through my unlit cat are ten times what they were during the smog test. That implies my P&G miles could be emitting 15-75X the average car's hydrocarbons, and 15-35X the average car's NOx!

I'm averaging 176% of the '08 EPA combined estimate. I can probably get 135-140% of EPA with engine on, cat lit, and normal emissions. That's sans P&G, and it's the direction I'm leaning now. Instead of 49.4 mpg, I'll get 39.2 mpg. Instead of using 55.7% of the average xB's fuel, I'll use 71.4%