[A4] A4 clutchless shifting
stephen at kormilo.ca
Sat Apr 21 11:58:22 EDT 2007
Robert King wrote:
> On 4/20/07, Tyson Varosyan <tyson at up-times.com> wrote:
>> I would be curious to see the numbers of your fuel mileage when turning your
>> car on/off at lights. Fact is, unless you got some mondo long lights, I
>> would bet that you come out losing money. Reason being, the startup fuel map
>> on just about any car is SO RICH that you would be better off idling for 5
>> minutes than cranking for 2 seconds.
> Start-up fuel enrichment serves two purposes. First, a slightly rich
> mixture is easier to start. Secondly, on a cold engine, the mixture
> is run right to pass unburned fuel into the exhaust system (along with
> fresh air injected to burn that fuel,) to light off the catalytic
> converters faster. Once the car has warmed up (usually above 160
> degrees or so,) the cold-idle strategy isn't used again.
Big snip of Robert's remaining comments, with which I agree....
Information I have read indicates that turning off a warm engine will
save fuel if it remains off for ~20s or more. Also, I indicated that I
didn't _always_ do this:
> Actually, with the recent high fuel prices, I will turn the engine off if I just
> 'miss' the light & know that it's a longish stop.
There are quite a few of these long lights around here, especially in
Nanaimo. Having said that, living 'out of town', a lot of my driving is
on the highway, so I don't expect a major difference on the average
consumption over a year. Having said that, every little bit counts, IMO.
BTW, my average fuel consumption over the past year is 9.39 l/100km or
~30 miles/Imperial gallon or ~25 miles/US gallon. Not too bad, IMO.
Nanoose Bay, BC
2002 Audi A4 3.0 - Silver
1998.5 Audi A4 2.8 - Silver
1985 Mazda Rx7 GSL-SE - Black
email: stephen at kormilo.ca
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