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October 22, 2010

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John

The reason it show a "8" is that it has to check all elements of the figure. Remember the old hand-held LCD calculators? It's like that.

Jack

The '8' is most likely the result of all the lights on the seven-segment display being initially lit (http://en.wikipedia.org/wiki/Seven_segment_display). I don't think it is a hint of anything to come, although I suppose we never know.

HK Lee

I think I can explain why the "8" shows up. When you first start your car all the warning lights turn on temporarily so you can diagnose a non-functioning light. For a digital numeric display you get the number "8" when all the little LEDs light up. This is also why your odometer will read "888888" during this test.

FYI, I drive a late model manual VW and it, too, shows the gear you're in on the instrument panel. Even more interesting is how the computer will try to tell you when to switch gears. A little up arrow flashes next to the gear number when your revs climb too high and a dot tells you it's happy with your current gear. I'm guessing this was programmed with fuel economy in mind.

Greg H

Seems to me the "8" is just a power-up test of all the segments in the number. And perhaps this feature is just a way for Subaru to maintain parts consistency (dash) between the stick and the auto.

But, I think the interesting aspect is that the gearbox itself would need a number of contacts to be able to tell what gear it's in. That's got to cost a few bucks. So... why does Subaru's engine computer want to know what gear the transmission is in? The clutch switch can tell that the gears are about to be changed and to change engine timing, etc.

I'm thinking that it may have to do with warranty claims, where the ECU records any "gear abuse" events.

Frank

Audi S4 with 6 Speed Manual Transmission has a feature called "Gearshift Indicator" on the Driver Information Display (Center display of the instrument cluster) which shows the current gear engaged and the computer's suggestion to shift up or down to conserve fuel.

Bepp

Jim,

Talk to anybody who has driven a Escort Cosworth from the 90's. Getting lost in the gears was very common with the 7 speed gearbox.

As for the "8" as a diagnostic test number that is easy it tests every segment at once.

BrightBulb

8 is a test of the led display as all other numbers use only part of the led segments

Carlos

Maybe Subaru does have an 8-speed manual in the works. The more likely explanation is that as the IP was going through the diagnostic test, it needed to make sure that all individual light elements of the gear number display were working. In order to do that, the number "8" would be displayed.

Jim Kenzie

Hi Greg:

To my knowledge, Nissan is the only one so far to take full advantage of that 'contacts in the gearbox' thing with the auto-downshift function in the 370Z.

These contacts 'know' what gear you're in and what gear you're heading for, and instruct the engine management computer to rev the engine so it matches the revs needed for the lower gear.

Those who think they're pretty good at heel-and-toe downshifting would love to believe it isn't as good as they are (John Henry versus the steam drill).

In this case, the steam drill wins - it really DOES work.

The engineers I spoke with at Nissan said that the principle seems simple, but it took a lot of detail engineering to make it work as seamlessly as it does.

Score another point for technology.

Jim Kenzie

Jim Kenzie

Hi Frank:

When I drove the S4 I was probably holding on so tight I didn't notice...

Jim Kenzie

Greg H

Thanks for the response, Jim. I can easily believe it was tricky to get the Nissan setup to work properly.

Sounds like the first "driver beneficial" arrangement that makes use of drive-by-wire instead of cable actuated throttle. Most of the drive-by-wire benefits are in lower emissions and probably less engine abuse cases (warranty issues again).

But Nissan's tech then opens up the possibility of up and downshifts with no clutch at all. Once the car is rolling, no clutch needed! I've had the misfortune of having a clutch die on the road due to hydraulic failure (a few times now), and had to limp home using no clutch, and obviously never coming to a complete stop. If the revs are matched, the dogs just slide in.

Greg

Jim Kenzie

Hi Greg:

The electronic throttles do in fact aid emissions, but they also can improve performance. Instead of being 'throttle controls' as such, they are now 'torque taps' - your right foot decides how much torque you want the engine to produce, and the engine management computer can modulate - yes, the throttle, but also the timing of both ignition and camshafts (in many cases) - even the transmission - to achieve that goal in the most efficient manner.

I had the clutch cable break on my old VW Jetta Diesel once. THAT was a long, hard slog up Yonge Street to my mechanic, trying to arrive at the lights just as they were turning green, starting the car IN gear when I couldn't make that work (the clutch interlocks mean you can't do THAT these days, unfortunately), clutchless shifting all the way.

Yeah, it probably would have been safer and smarter to just call CAA...

BTW, I knew a guy in High School who could START a stick-shift car from rest without using the clutch! Never did figure out how he did that...

Jim

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