[Gmecm] Re: Fuel economy

[Dan Barcroft]

On wbo2.com <http://wbo2.com>'s yahoo message board I have read talk of 
people wanting to program the narrow band output to be centered at something 
like 16:1 insted of 14.7:1. Would anyone care to dicuss how this would screw 
with BLM's and such. Could there be something like a WBO2 driven hwy mode 
that could be programed but still use the NBO2 for every other condition? I 
guess if you want to go that far you would be better off using the full WB 
input???

-- 
Dan Barcroft
triaged at gmail.com

On 9/14/05, Cowen <captain_krill at yahoo.com> wrote:
> 
> Darrell,
> Take a look at what the guys on the Wide Band O2
> sensor sites are saying about fuel economy. Our
> Narrow band OEM O2 sensors are most sensitive at a
> fuel ratio slightly richer than optmial for economy.
> One theory is, if you can get your O2 sensor to work
> at leaner ratios, maybe you can tune for better
> economy.
> 
> The other option people have mentioned is that some GM
> ECMs (which bins??) have a disabled "Highway Mode" in
> their program. From what I understand, Highway Mode
> is designed to ignore that narrow band OEM O2 sensor,
> only when a bunch of factors convince the ECM you're
> under light load and at highway speeds. Again, this
> allows for tuning a leaner mixture than the OEM O2
> sensor could use. Unfortunately, the ECM is blind in
> this mode. It's not referencing the O2 sensor, so it
> can't monitor emissions or mixture. As a result, US
> federal gov't has dissallowed use of Higthway Mode
> from the factory. It can also be pretty destructive
> if enabled, because with no reference to the O2
> sensor, there's every possibility of running WAY off
> on the mixture. Too lean and you melt pistons! The
> ECM wouldn't know to correct mixture problems because
> it's not even looking when in Highway Mode. If you
> have an '87 2.8l with 300,000 miles on it and one
> injector is badly plugged, while another one or two
> are partially plugged, they won't allow as much fuel
> through as they would have on a new car (for which the
> Highway Mode was written), and you'll run lean. You
> can probably imagine other scenarios where a high
> mileage car with 20 year old components may vary from
> factory norms!
> 
> Those are the only two ideas for increasing mileage I
> can think of that are directly related to the
> injection. Of course better intake and exhaust help,
> so that you're putting less energy into
> pulling/pushing gasses around. You can also make sure
> your tires are pumped up at least to the maximum on
> the sidewall. If replacing your tires, consider going
> as narrow as possible in as smooth a tread as you dare
> for reduced angular inertia and rolling resistance.
> Keep your car light (leave the jack and spare at home,
> and buy a smaller battery, etc.) to reduce mass you
> have to accelerate. The electric cars are great
> inspiration for this! I've heard the carpet from a
> Viper is hollow to reduce mass - maybe you should put
> some of that in the Cavalier! :)
> 
> There are also plenty of (snake oil?) products that
> purport to imrove economy, but according to US Gov't
> EPA tests, they either hurt emissions or cost more
> than the fuel they save or both! While researching an
> article on what to do to pass emissions tests, I did
> come across a few products that did reduce consumption
> without increasing emissions. According to the EPA
> tests
> (http://www.smartcarfinder.com/articles/gas/04.htm),
> those product are things like an airdam/spoiler kit,
> underdrive pulleys for your accessories, and driver
> behaviour modifiers like idle alarms and bricks under
> the gas pedal! Does anyone else have any ideas??
> 
> I fear that most of these ideas will make so little
> overall difference as to be moot.
> 
> 
> 
> **********************END TRANSMISSION**********************
>
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