The dirty cost of one man's hypermiling?

[user removed]

Sentra I gave this some thought and I am a solution oriented type of person so here goes.

You use a lot of EOC, which may also kill the preheat to your O2 sensor. If the sensor cools off enough due to the lack of power to preheat the sensor then you may be able to mitigate the issue considerably by making the preheat work during the engine off coasting portion of your glides. Keep the stove on when the engine is off so to say.

Another method of increasing the heat retention of the catalyst would be to have it ceramic coated, or to cover it with fire proof insulation and maybe an additional metal cover over the insulation. In the old days asbestos would have been ideal, but that's a nasty thing to mess these days.

The heated sensor would provide you with open loop operation virtually immediately on restart, so you would definitely improve the emissions going to the cat. It may be that your system does this already, but if not then a slight mod.

The heat retention using additional insulation would most likely vastly improve the average temp of the cat and it's ability to do it's job properly.

It seems like you have the instrumentation to verify any improvement, and I hope it meets your goals without costing you too much economy. Heck who knows it may actually help your economy but that may be wishful thinking, but if so then you would know you have maintained your sense of personal integrity and environmental responsibility.

Don't be too hard on him Metro, his concerns may actually lead us to a solution, which is a benefit to all who use the highest levels of technique. I think it might be possible to have the best of both worlds, and the maintaining of heat to the sensor is really the key to precision mixture control.

Anyway, that's my story and I am sticking to it for now. Let us know how it goes, and if I can help you can count on me, especially since us home boys on the right coast get pollution from all over the country.


Just trying to inject a little humor.
Mech

[MetroMPG]

Originally Posted by SentraSE-R

How about a compromise change to "The dirty cost of one man's hypermiling?"

Sounds reasonable to me. Thanks.

Originally Posted by Old Mechanic

Don't be too hard on him Metro, his concerns may actually lead us to a solution, which is a benefit to all

It's not personal - and as I said, I wasn't objecting to the thesis of the post at all.

Here's my concern: this thread title will be picked up in Google searches, and will be intentionally taken out of context by people who have an axe to grind against the general notion of driving to save fuel and/or modding to save fuel. It will become a source of misinformation fed to people on other sites who object to the entire concept of "hypermiling" and who won't read past the title. It's happened before. That's why I'm sensitive about a title that implies more than it should.

---

I am looking forward to reading about where you decide to go from here, Darrell.

FYI, I gave up using P&G as a routine driving technique a couple of years ago, partly because of the question of emissions which you laid out, partly because I find it tedious on anything but the shortest trips, and partly because it's arguably harder on the vehicle mechanically.

It's one reason I jumped at the chance to get the Insight: P&G levels of fuel economy without the calisthenics.

[SentraSE-R]

Thanks to everyone concerned with how this will affect my future as a hypermiler. If I've boycotted Exxon for nearly 23 years, I'm not about to emulate it on a smaller scale.

My hypermiling caused the CEL/MIL that I cleared with my Ultra-gauge back in October. Key-off-on toggling with the engine off and car rolling causes multiple cylinder misfire trouble codes for my car - P0301, P0302, P0303, and P0304 - the next time I turn the key on to start the car, even before the engine cranks over. The ECU apparently sees vehicle speed inappropriate with some cylinder functions, and triggers the TCs. My kill switch stopped those TCs, but a kill switch connector came loose in October, I reverted to key-off-on coasting, triggered the TCs, and I cleared them.

For those of you unfamiliar with CA smog testing, the California Air Resources Board mandates our test stations do complete visual, functional, and emissions tests. We can't skate by just on a CEL/MIL not lit, or an OBDII scan for readiness flags set.

The visual inspection checks for disconnected hoses, non-OEM or non-CARB-approved intake/exhaust/header, any alterations that might affect emissions. I ran a WAI for ~2 years, but removed it before the smog testing, because it would trigger an instant fail.

The functional test checks if the MIL is lit, and if not, if the drive cycle readiness flags are set. A lit MIL is an automatic fail. A readiness flag unset is also a fail. That's what my xB failed. I hadn't completed at least two drive cycles. One was the catalytic converter drive cycle. The other was the evaporative emissions purge drive cycle.

There's a lot of misinformation out there about passing the drive cycle monitors. Some people think you need to drive a car 100 miles. Some say it can take weeks and thousands of miles. In my case, 4 months and 800 miles of P&G wasn't nearly enough. The Scion community found the answers.

In my case, the cat drive cycle is 15 minutes of steady driving between 60 and 100 kph (~37-61 mph). I hadn't done that in 4 months! The evap cycle starts 5 hours after the ignition key is switched off, if coolant temperature is below 90 degrees. If not, it tries to start 2 hours later, etc.

I went out and drove up the nearest highway at 55 mph for 15 minutes, turned around and drove back at the same speed, and went back to the smog test station. I'd set the cat monitor readiness flag. They told me to drive 50-60 more miles, and the evap flag would set. I knew it would set overnight, so I drove home and parked my box. It passed the next morning.

Finally, we're ready to talk about CARB emissions testing, and to determine whether my driving causes more pollution than the average Scion xB.

[SentraSE-R]

Darin, you have the power to change the title, so go ahead. I can't figure out how to do it, probably because I can't.

[tradosaurus]

Move out of California and your "problems" will be solved.

[SentraSE-R]

The CARB emissions test goes something like this. The smog test operator drives your car onto a set of rollers and sticks a sniffer up its tailpipe. The sniffer is connected to a test equipment computer. The op lets your car warm up. In the summer he has a big fan to blow on your radiator. I made sure to remove my grill blocks for the test.

The op enters your car's data. The computer looks up the allowable emissions for your year/make/model/engine/transmission. At some point, a drive cycle begins, where the op has to have the car in gear, driving the rollers, watching the computer screen, keeping the vehicle speed/rpm between two lines. That's where the ~1700 and ~2800 rpm test values come from.

As you can see from the scanned test results, average HC is 4 ppm at both low and high rpm, and my car initially tested 62 and 16 with 64 ppm max to pass. That's >15X normal, and 4X, respectively, with the cat lit. On the retest, my car tested 39 and 14 ppm. That's still nearly 10 times the average at low rpm, and 3.5X at higher rpm for HC.

NO isn't much better. The average car tests 16 ppm at low rpm and 18 ppm at higher rpm. My xB initially tested 101 and 89 ppm, ~6X and ~5X the average. On the retest, my car tested 105 and 74 ppm, ~7X and ~4X the average. Again, this is with the cat fully lit.

My car's CO emission numbers were 6X and 2X the average car on initial testing, and 2X and 1X the average on retest.

I've got some errands to run for a few hours, but it's clear my car has a problem. It is well-maintained. Spark plugs were replaced <10k miles ago. Oil is 5W-20W synthetic. Air filter is clean.

Mech, I'm pretty sure the O2 sensor heat stays on during coasting, since my kill switch only cuts the fuel injector common hot wire.

Tradosaurus, no, where I happen to live doesn't address the problem at all.

[FXSTi]

Originally Posted by tradosaurus

Move out of California and your "problems" will be solved.

His concern is not passing the smog check, it is reducing his impact on the planet. Just because he might not get checked for it somewhere else, doesn't mean he isn't polluting excessively.

Kirk

[Daox]

Do you have the results from your last test (before this round)?

[rmay635703]

Originally Posted by FXSTi

His concern is not passing the smog check, it is reducing his impact on the planet. Just because he might not get checked for it somewhere else, doesn't mean he isn't polluting excessively.

Kirk

I applaud him for critical thinking but these type of threads that focus on a single point ignore the big picture.

He may reduce or increase his personal pollution but what about all the pollution upstream that got that gallon of gas in his tank? I have never seen a hard estimate but from what I was able to read roughly 100x the pollution emitted from the car itself burning a gallon of gas is created during the exploration, drilling, cracking, refinement and transport of that 1 gallon of gas to his car. This includes many types of pollution more hanous than his exhaust that go in land, sea and air. It also requires manpower and a variety of other resources that aren't fully explained or mentioned that are needed as a result.

I would stand by reducing fuel consumption is more important than slight changes in exhaust makeup.

[brucey]

This sounds like such a perfect test for Mythbusters, unless one of you guys have a mobile emissions testing center.

I'm still in the "FE is more important than emissions." camp myself. If you burn half as much fuel but produce twice as much emissions doing it, you're still ahead because that fuel is not having to be extracted and pumped and refined and piped and stored and shipped and pumped and burned.