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Old 02-18-2013, 06:10 PM   #1
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Skip Shifting?

In a Camaro I used to own (v8) it came with a feature called "skip shift" wich at slower driving locked up second gear causing you to go from 1st to 3rd. They claimed it was to conserve fuel. And possibly with much more torque coming from the v8 this may have had an effect.

I have tried this on my saturn many times (1.9L 4 cyl) but it doesnt seem to make a difference that I can tell. I run a 1-3-5th pattern keeping the RPMs very low. But I wonder if it has an effect since i still have to press the pedal fairly hard to keep it excelerating.

Anyone have any insight on this?
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Old 02-19-2013, 01:30 AM   #2
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No clue if it helps or not, but I skip fourth and go third to fifth on occasion just for fun lol
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Old 02-19-2013, 02:47 AM   #3
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I think it works better on high-torque engines. In a smaller engine, I have found that it usually works well just to upshift to the next gear as early as possible, not necessarily skipping gears.
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Old 02-19-2013, 04:28 AM   #4
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I remember the feature- actually I thought it sent you from 1st to 4th. I never had one but I guess I always thought it was too big of a gear ratio difference to work, because you'd have to rev up in 1st gear then bog in 4th.

But as a rule of thumb, shifting early (and being light on the throttle) helps save gas.

-Bob C.
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Old 02-19-2013, 10:46 AM   #5
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I think on AT:s "winter mode" or "skip shifting" mostly gives a smoother launch with less torque on the driving wheels. Starting from second makes the speed difference from input to output in the torque converter much larger making it work less efficient pumping more fluid around until the car is up to optimal speed for 2:nd gear.

On MT:s it's many times real useful to skip gears to enable a firmer acceleration without too much lossy pausing between shifts. Using 1:st, 2:nd, skipping to 4:th if the final speed is around 25mph or 1:st, 2:nd, 3:rd skipping to 5:th if the final speed is 30mph or above. Then when engine braking towards a corner or roundabout skipping from 5:th to 3:rd (engine brakeing) and then using only 3:rd gear through the turns accelerating up to 30 or 45 skipping to 5:th again. This way you eliminate several lossy clutch operations and shifts and works the ones you use to several advantages: more engine braking in dfco-mode, less attention to shifting and more on the actual driving and planning, and a firmer acceleration out of the turn using the engine more efficiently (less pumping losses). This gives actually a very smooth driving around town.

An AT almost does this when you accelerate firmly, it stays in gear during the accelleration and when you take your foot of the gas it up-shifts several times fast to the highest suitable gear. Only difference is it has to shift through all of the gears even when it "knows" is doesn't need them.
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Old 02-19-2013, 05:01 PM   #6
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The way I see it, CAGS (Computer Aided Gear Selection, or coloquially, skip shift) wasn't actually for real drivers to save real fuel; it was a cheat for the EPA fuel economy rating system intended for the owner to disable the day he drove it off the lot. That's not to say that skip shifting is a worthless concept, just that that specific forced skip shifting isn't likely to help.

It's definitely worth experimenting with different patterns.
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Old 02-19-2013, 05:48 PM   #7
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Quote:
Originally Posted by theholycow View Post
wasn't actually for real drivers to save real fuel; it was a cheat for the EPA fuel economy rating system intended for the owner to disable the day he drove it off the lot.
Yeah you are probalby right about this. It makes sense. Even today manufacturers are trying to "cheat their way" to claim better MPGs. However on my Camaro there was no way to turn it off at all (well it automatically shut off if you accellerated hard in first) But the more powerfull and less efficient Corvette of the same year you could turn it off and they were very similar setups. Didn't make much sense. The only thing I was able to turn off and on was traction control wich was always part of my startup routine: Neutral, crank it, T/C off button, 1st gear and away we go! I never ran with it on! I was actual able to get around 28-29 mpg on the highway in 6th gear in that car. Not too shabby for a LT1 v8 that made 285 hp from the factory before I started toying with it lol. Doesn't sound like much today but in 1997 it was good power!
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Old 02-19-2013, 05:54 PM   #8
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Quote:
Originally Posted by krazy Dan View Post
I run a 1-3-5th pattern keeping the RPMs very low.
Well, I often use this same pattern (and sometimes 2-4-5 or 2-5 when not starting from a dead stop) in my small car (1.0l i4), to get quickly out of those lower gears. I'm not even gentle, I just want to get out of the inefficient gears as soon as possible, without too much revving.

Hell, there are 5 gears while it can cruise under 25mph in 5th... there's just too many of them I mean, it's crowded down there, then nothing... I'm not used to it. On my motorcycle (650cc single) I can't even use 5th under forty-something mph. So all the gears are different, they have meaning. But having to shift 4 times through a few almost identical gears to double the time to get to the (already very short) 5th...?

I'm not sure that skipping gears is good for FE, but I don't think it's too bad. Accelerating gives the engine a proper load, and if it doesn't rev too fast it works at the most efficient part of its BSFC. But for cruising I always use the highest possible gear.
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Old 02-19-2013, 06:54 PM   #9
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Quote:
Originally Posted by krazy Dan View Post
However on my Camaro there was no way to turn it off at all
You had to do a little bit of wiring. The exact procedure differs by year, but here's an example:
Eliminating "Skip Shift"
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Old 02-20-2013, 12:59 AM   #10
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Quote:
Originally Posted by alvaro84 View Post
Well, I often use this same pattern (and sometimes 2-4-5 or 2-5 when not starting from a dead stop) in my small car (1.0l i4), to get quickly out of those lower gears. I'm not even gentle, I just want to get out of the inefficient gears as soon as possible, without too much revving.

Hell, there are 5 gears while it can cruise under 25mph in 5th... there's just too many of them I mean, it's crowded down there, then nothing... I'm not used to it. On my motorcycle (650cc single) I can't even use 5th under forty-something mph. So all the gears are different, they have meaning. But having to shift 4 times through a few almost identical gears to double the time to get to the (already very short) 5th...?

I'm not sure that skipping gears is good for FE, but I don't think it's too bad. Accelerating gives the engine a proper load, and if it doesn't rev too fast it works at the most efficient part of its BSFC. But for cruising I always use the highest possible gear.
I'm pretty sure it does save fuel skipping gears, if it'll get you faster up to the highest possible gear for the intended final cruising speed. When there is slow accelerating traffic ahead stepping through all of the gears might be better.
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