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Old 02-02-2012, 08:35 AM   #65 (permalink)
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Originally Posted by SentraSE-R View Post
It's been a long time since I did NICE-on P&G, but IIRC, I got mid-40s mpg averaging ~30 mph. I got mid-50s mpg @32 mph in 5th gear cruise control on the same drive.

Are the data there to support an assumption that my engine is an average polluter when run normally (smog test 3)?

Are there any alternate theories with equal likelihood to dethrone P&G from being the cause of the above-average air pollution test results? I realize 4 months of relative inactivity, or one month of complete inactivity alone could be the cause, but given my P&G history, and the return to normal HC results after my 900 mile "normal" driving, is there another theory with equal likelihood?

Does anyone see any major logic flaw in my suspicion that I'm dumping 15-75X the average xB's HC into the air with unlit cat P&G? FWIW, my constantly-lit-cat drive today saw the cat temps staying between 985 and 1339 degrees F.

Mech, I was driving 100 miles/night looking for rattlesnakes in the desert when I was that age. Gas was 18.9 cents/gallon. Life was good. When I was younger, midday LA smog looked like nighttime Central Valley Tule Fog. We'd play touch football in air so foul, it gave us shortness of breath. I don't want my gaming behavior to swing us back in that direction.

dcb, I wish I could make more sense out of those data. The NOx spike seems strange. I'm happy to see the HC back to normal.

I P&Ged, I failed to light the cat, and my emission values were abnormally high.

I lit the cat for 100 miles, my emission values dropped, and were still abnormally high.

I lit the cat for 900 miles, my emission values returned to normal. Is there any other cause and effect relationship going on here?
In my posts 36 and 40 on this thread, you have experienced what I speculated in those two threads. The manufacturers design a car for "normal" operation. EOC during 50-75% of a driving cycle falls out of that parameter.
Now that you have the two extremes and a fairly conclusive set of data, maybe there is a point of compromise that you can reach where you have the desirable emissions readings and close to the same mileage as before.

I watched your video showing your technique and appreciate the effort to show all of us how it's done. Looks like you might just need to adjust the technique to maintain cat function to the greatest extent possible to have the best of both worlds.

Since you can monitor cat temps, the remaining unknown is how long does it take serious techniques to affect emissions. It would seem like the longer trip "undid" the effects of years of previous driving for best mileage. Now the question is how do you sacrifice some economy, as little as possible, in order to produce the lowest emissions that will satisfy your opposing goal of normal percentages.

The 100 mile trip that reduced, versus the 900 mile trip that brought them to normal. What is required now to maintain the reduction?

That is the unanswered question.

Is it a maintain the low emissions issue, or a take a trip issue? You have the results of the extremes of to little and too much, meaning do you have to take a trip frequently or will the shorter trip be all that is necessary to maintain ideal function? I think there is a balance between the two, but if the longer trip "repaired' the system then maybe the shorter trip, or possibly just a change in technique be all that is necessary?

My speculation would be to drive with engine on and monitor cat temps, with the objective of keeping temps in the range above the cat function threshold.
Can cat temps be maintained with a reasonable amount of EOC? Would just driving with engine on to warm everything up, then manitaining a minumum effective cat temp be the solution?

Sadly increasing average cat temps requires wasting more heat energy, which means the choice is best mileage or lowest emissions, which is why I have always been opposed to adding "stuff" to control emissions, but that is a topic for another thread.

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