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Old 06-16-2008, 10:25 AM   #11 (permalink)
'07 Saab 9-3 Sedan 2.0T S
 
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How about Tiptronic?

I don't have a winter mode, but I do have a Tiptronic tranny that allows starts in third gear.

Anybody do this in a systematic way to determine if it saves gas?

I would think that a higher gear would allow you to keep the throttle open more. Just like short shifting a manual.

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Old 06-16-2008, 10:55 AM   #12 (permalink)
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Quote:
Originally Posted by Krieg View Post
I don't have a winter mode, but I do have a Tiptronic tranny that allows starts in third gear.

Anybody do this in a systematic way to determine if it saves gas?

I would think that a higher gear would allow you to keep the throttle open more. Just like short shifting a manual.
Both of our vehicles have the ability to start in 2nd (the TSX has the slap-shift or Tiptronic-style gate).

The impression that I get, is you're really fighting the torque converter from a standing start in 2nd or 3rd. The practice I use, is to get the automatic in the next gear as quickly as possible (with a target engine speed). Otherwise, your energy is going into torque disbursement instead of to the wheels for forward motion.

Where it may be beneficial, is to start in 2nd on a downhill grade if light throttle input is required.

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Old 06-16-2008, 12:50 PM   #13 (permalink)
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The winter button has nothing to do with tracton control. Infact, I hear a lot of misunderstanding as to how traction control even works. Yes it is completely tied into ABS, but it nothing on how the engine reduces the actual torque to the torque requested by the body control module of the car. All the module does it look at wheel slip, driver intent, enginer torque, etc. and either reduce the engine torque via a communication protocal to the engine ecu and in most cases build brake pressure to certain wheels to stop them from spinning wildly.

Traction control in no way helps your fuel economy because it will allow your wheels to slip and "waste" energy using the brakes to keep the wheel slip down or nill. This waste energy from the engine and will hurt fuel mileage not like anything described above, but from just letting your wheels spin.

The witner mode button just gets you into such a high gear that you cannot produce enough torque to make the wheel spin, for the most part, causing no need for a traction control system in most cases, but also limiting your acceleration greately. This COULD save you gas mileage, would be a good test!!!

(FYI, I'm a slip control systems engineer in charge of system/vehicle integration for new products)
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Old 06-16-2008, 04:57 PM   #14 (permalink)
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Quote:
The impression that I get, is you're really fighting the torque converter from a standing start in 2nd or 3rd. The practice I use, is to get the automatic in the next gear as quickly as possible (with a target engine speed). Otherwise, your energy is going into torque disbursement instead of to the wheels for forward motion.
What do you mean by "fighting the TC"?

Your car makes a lot of noise but doesn't really go anywhere?

I'm going to start messing around with this. I'm already shifting into neutral at lights and downshifting to a stop, as well as driving on the highway in M5 rather than Drive (ensures that the TC is locked and no downshifts occur when in cruise).
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Old 06-16-2008, 05:29 PM   #15 (permalink)
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Quote:
Originally Posted by Krieg View Post
What do you mean by "fighting the TC"?

Your car makes a lot of noise but doesn't really go anywhere?
Yeah, pretty much

If you have a ScanGauge or similar, monitor engine loads during the startup in a high gear vs. low. I see your Saab has a turbo -- perhaps it will get it spooled up sooner so you can effectively use the power, earlier? Just a theory.

Truthfully, the best way to do it, is to test -- and report.

Quote:
...as well as driving on the highway in M5 rather than Drive (ensures that the TC is locked and no downshifts occur when in cruise).
I do the exact same with the TSX 99% of the time. It prevents that rogue downshift on hills. If I keep it above 50 mph at high loads, the TC stays engaged. The throttle is "fly-by-wire", so I'm not sure what it's really doing in there (the SG registers the driver's input and not the actual throttle plate position). With the 'Teg, it's a different situation altogether. The old-school 1st and 2nd gear holds, D3 (locks-out hill-logic and runs automatic decisions to shift in gears 1, 2, and 3), and the final D4.

I've tried starting in 2nd in both cars, and it just lugs and loads up. I would liken it to slipping the clutch in a manual.

Has anyone had additional experience with this procedure?

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Old 06-17-2008, 08:09 AM   #16 (permalink)
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Well, I tried it on the way home yesterday.

Starting in 3rd, the turbo was spooling much more than a lazy acceleration in 1st.

It actually made driving in traffic a little easier. Slower acceleration means less back and forth with the accelerator and brake.

But I don't think that spooling the turbo is the way to improve mileage.

I really need to buy the Scangauge II. It's on my list of things to get, I just need the right "opportunity". Translated: get it when my wife isn't looking.
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Old 06-21-2008, 11:49 PM   #17 (permalink)
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My '99 Saab 9-5 has the Winter mode and the Sport mode. As for the Volvo, W starts are in 3rd gear. But Saab adds a different throttle opening program to the electronic throttle, so you have to depress the pedal much more for the same amount of torque. Sport mode has much higher shift points and a throttle map that is the opposite: small press - big torque. The winter mode makes it easier to control in slippery conditions. (I don't have traction control). The Sport button is usually referred to as the "Silly" button.
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Old 01-16-2009, 02:34 PM   #18 (permalink)
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I have played with the winter mode on my volvo and its a really strange sensation to use it. From a standing stop the engine roars and roars (but stays under 2000 rpm) and after about 3 seconds the car has moved about a foot! After that it begins to accelerates more quickly. This is probably great in slippery conditions because the Volvo throttles are kind of sensitive otherwise.

The winter mode is therefore too slow to use in traffic when there are people behind you. What I found was that if I moved off in normal mode and after a few feet I pushed the W button the car immediately went into third gear. This could result in fuel savings but I did not test it.


Last edited by instarx; 01-16-2009 at 03:35 PM..
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