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Manual shift with an automatic- Who uses it? Does it help? Is it bad long term?

10K views 35 replies 16 participants last post by  gdipilato 
#1 ·
Hello all,

I wanted to see if anyone uses the manual shift to save gas. Anyone have input on what I should be getting city if shifting below 3,000 RPM's in a 2011 RS? Is it bad for the car long term?

Also, any recommondations for gapping my sparkplugs? My plugs were all inconsistantly gapped below .25...I tried gapping them to.35 but my MPGs went way down.. then tried .30 and it is still down but not much... thinking of trying .25 to see if it helps. Does it take time to see results after gapping the sparkplugs?

Thanks!
Mike
 
#2 ·
The only time I use the manual shift is when I'm feeling a little frisky and want to get down on it! Of course this does nothing to help the fuel economy so I cant address your first question. Set you plugs at 28, you should be able to tell the difference immediately.
 
#3 ·
Shift at 2000-2300 whenever possible to keep the car from revving high. This engine has lots of low-end power and when it revs to 3000+, it just wastes fuel.

Manually shifting the automatic doesn't harm anything - the transmission works exactly as it would normally except the car isn't horribly picking shift points.

Plugs gapped at .030" should do just fine and may improve your response off-the-line. Don't fiddle with the iridium plugs too much or you'll break the tips.
 
#6 · (Edited)
yeah i actually used manual mode quite a bit when i was stock. after the tune i dont find i need to. If your drive also includes a lot of hills and elevation changes its much easier to stick it in 6th and hold than to try to guess what throttle position is just enough to hold decent momentum without the computer downshifting. With the trifecta tune only when im going to be going over very steep grades ill bump it into high boost mode and stick it in 6th and putter right up. Like someone else mentioned once in manual mode at a stop you can select 3rd and still launch with decent speed. even stock with just a K&N drop in filter and resonator delete i could out pull most traffic in third. tuned is no problem at all. Also with the manual mode the first time it will select 1st gear automatically at a stop but mine learned that if i launch in third it will only drop to third.
 
#11 ·
I use the manual mode, but mostly for holding a lower gear for a corner, hills or slowing down for a stop sign. I am of the strong belief of getting up to your final speed quickly burns less fuel. Sure I burn more fuel when I am getting on it but let say I want to go 60mph, I certainly burn less in my 8-10 second blast and leveling out at 40mpg+ for a longer period than taking forever to get there shifting at 2,000RPM and constantly being under load for longer.

This is also why GM geared 1st so low, to get the 3,000LB car moving off the line with less load. Use 1st if you want to save fuel, just make sure to shift at 2500-3000RPM max. This gear is just meant to get you rolling, and the 2 seconds max you are actually at 3,000 doesn't burn that much fuel.

I usually shift at 2,500-3,000RPM in every gear, thought sometimes I take 1-4 as high as 5,000RPM. I average 36-37mpg driving this way(60% highway).
 
#14 ·
I use the manual mode, but mostly for holding a lower gear for a corner, hills or slowing down for a stop sign. I am of the strong belief of getting up to your final speed quickly burns less fuel. Sure I burn more fuel when I am getting on it but let say I want to go 60mph, I certainly burn less in my 8-10 second blast and leveling out at 40mpg+ for a longer period than taking forever to get there shifting at 2,000RPM and constantly being under load for longer.

This is also why GM geared 1st so low, to get the 3,000LB car moving off the line with less load. Use 1st if you want to save fuel, just make sure to shift at 2500-3000RPM max. This gear is just meant to get you rolling, and the 2 seconds max you are actually at 3,000 doesn't burn that much fuel.

I usually shift at 2,500-3,000RPM in every gear, thought sometimes I take 1-4 as high as 5,000RPM. I average 36-37mpg driving this way(60% highway).
My fuel economy has gone up by about 8 MPG once I started targeting the end of shift starting point for the new gear no higher than 1400 RPM. This still lets you get off the line reasonably quickly as the first shift is at 2300 RPM and the second shift is at 2000 RPM. Yes, I'm also doing other things like slowing down from 65 to 60 (which is safe on my morning commute) and even 55 in the afternoons (once again, a safe speed), but in heavy stop and go traffic there is a noticeable 6+ MPG increase just from changing my shift timing.
 
#17 · (Edited)
Buy the trifecta tune they fix the shifting to optimize it. If you want to shift the car yourself, buy a manual transmission car and be done with it.

2nd what spacedout said. The Automatic transmission gears (4.58 and 2.96) are specifically there to motivate this porkster. Skipping either is counterproductive.
 
#18 ·
Buy the trifecta tune they fix the shifting to optimize it. If you want to shift the car yourself, buy a manual transmission car and be done with it.
I'm doing it wrong.
 
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#20 ·
It is interesting reading about the different driving styles with auto. I mostly just leave my car in drive and even going down a slope at 50kph (30mph) the transmission senses when you don't want to go any faster and will hold a lower gear all by itself. I read something about this feature in my owners manual and it works, at least with a diesel and 6T45 anyway. High compression = good engine braking. The new 1.6 turbo senses when you are pushing along and will hold a gear when you slow for a corner to give a better exit as well. Holden re-tuned the transmission for sportier driving when required.
 
#26 ·
i have an A/T and used the manual shift when ever i m in traffic, it does help keep the mpg up a bit. i believe that it does help improve mpg around the city. i get about 38mpg even when hitting nyc traffic on the highways.
 
#27 ·
my 2012 has no noticable shudder launching in third. but i also am tuned and have the k&n drop in and resonator delete. That being said after the tune i rarely use manual mode unless im going up steep hills or plan on doing spirited driving, which i generally try to avoid now. I can see torque converter slippage being an issue though. I am glad you brought that up. I guess every car is different though even among the same models.

As far as driving for economy i can see both sides of the coin. I can see how minimal revs and partial throttle would yeild greater economy. The flip side being that using greater throttle opening and higher revs to attain the same speed quicker, say 10 seconds at 50 to 75% throttle compared to 30 seconds at 20-30% throttle could yeild greater fuel savings. However repeated testing and real world ancedotal data always seems to support low revs and less jack rabbit starts the better. Every car though operates under different ideal load and fueling. So i say find the method which yields the greatest fuel savings for your car.
 
#32 ·
I averaged 38.4 over a trip last week from eastern KY to the smokies, in and around the tenn/NC state line. 65% highway 20% back Roads 15% bumper to bumper traffic in congested area. I ran 5 to 10 over on the highway with speeds avg between 65-80. This route also features some extreme elevation changes and frequent steep grades. On the interstate at anything less than 70 mph I'll show 42-50 instant mpg. Above 70 that dropped slightly to between 38-46 instant. My car seems to avg less than 3% difference and the total trip mpg was hand calculated, the dic showed 39.1 mpg
 
#36 ·
Ive started shifting manually in my LS. Not really because i hate how it normally shifts but it does make it a little smoother and its more fun so kind of a win win for me. I usually let it down shift by itself when slowing down but is downshifting bad for it? I try to shift at about 2500 rpm but will go to 3000 up hills.
 
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