So I have had my 01 SR5 4WD for about a month now and everything has seemed pretty normal. Sounds good and rides good around town and on the highway. I am getting what seems to be regular gas mileage too. This weekend I took it on my first trip and have a question about something I noticed. I went up to the mountains, and noticed a flat spot around 2500 rpms when climbing the hills. Is this just a downfall of an automatic transmission? I had to really step on the gas to get it to drop a gear and accelerate uphill. Is there a way to gain more power in the 2500 rpm range, or change the shift points perhaps? I have also noticed that when I am accelerating on flat ground, the shifts dont seem to do much to the rpm's it will shift around 2200 and only drop to around 2000 and then do the same thing again. Do these vehicles just try their hardest to stay around 2000? I would like to get a little more pulling power or torque, without putting the pedal all the way to the floor. Sorry this is so long winded, hopefully it makes sense and you guys can provide some input.
1st month impressions
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THEREALTOR1
New member
to change the shift points turn on the ECT, to get more pulling power turn off O/D. I drive around now with the ECT button on, definately makes the truck more spunky 
I'm pretty sure that's the torque converter locking and unlocking, not actual shifting. That 200 rpm is purely friction and fuel mileage loss.
to change the shift points turn on the ECT, to get more pulling power turn off O/D. I drive around now with the ECT button on, definately makes the truck more spunky
I'd rather leave the truck in the position that returns the best fuel mileage. If I have to hit the gas a bit harder to get the downshift, so what. If I wanted, I could even make it so that I got 3/4 throttle with the pedal only halfway depressed. At least that would only make a feel difference and not (through higher rpm operation) waste gas.
Pikeman
New member
I just manually shift my Auto when headed up into the mountains. With all my armor and gear I carry I usually pull it into 2nd and run up about 45 or so and about 3k RPMS. Seems to do real well instead of hunting for gears. If I leave it in drive and turn OD off it still hunts between the gears and that builds up heat in the transmission. Heat is the worst enemy of an Automatic. I am hoping to be able to re-gear in the near future to get it back in the power band where it is happy.
Highway/City I leave it in drive with OD on I only manually shift when off-road or going up long hills.
Highway/City I leave it in drive with OD on I only manually shift when off-road or going up long hills.
If only...
brian2sun
Elite Member
Naw, how open the throttle is the main thing that determines how much gas you're using - much more than rpms do. Punching it to make it downshift or adjusting your throttle to be at 3/4 open when the pedal is only 1/2 depressed would drink way more gas than just holding it at a higher rpm but low throttle. Not to mention, adjusting your throttle that much is not a good idea because you'd be idling way too high at rest.
Say you're going up a hill and you're pulling 3000 rpms with the throttle 1/4 open. You will burn through a lot less gas than if you upshifted and were at 2400 rmps but had to push it to 1/2 throttle. On a flat highway it's the same thing. The tires will passively push the engine up to higher rpms. So the engine may be turning fast, but it's turning mostly from momentum - not by fuel pushing cylinders down faster.
I get better mpgs with the ECT on if I'm in the mountains, but on flat I get better mpgs with it off.
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I forgot to mention something else I was curious about. When for the first 30 seconds or so moving after I start my vehicle (cold or warm, doesnt matter), it seems to make much more intake noise than normal. Then it stops and I get a more normal exhaust noise. In other words, it seems to suck more than blow at the beginning and then the opposite. Is this normal?
brian2sun
Elite Member
OK, so apparently one should just turn the engine off on a long flat stretch and let the tires passively propel the 4Runner...
Here's a thread in another forum where a member explains that lower rpm and higher throttle will save fuel, using published engine efficiency curves.
On MPGs, efficiency, torque curves and shifting - Subaru Impreza GC8 & RS Forum & Community: RS25.com
You can argue anecdotally all you want, but (with the exception of a lugging and improperly operating engine) you won't find experimental data to show that higher rpm operation is more efficient because it doesn't exist under the physical laws of our universe.
The ECT PWR button is to protect the engine from extended periods of high load, low rpm operation that can cause the transmission to overheat.
On MPGs, efficiency, torque curves and shifting - Subaru Impreza GC8 & RS Forum & Community: RS25.com
You can argue anecdotally all you want, but (with the exception of a lugging and improperly operating engine) you won't find experimental data to show that higher rpm operation is more efficient because it doesn't exist under the physical laws of our universe.
The ECT PWR button is to protect the engine from extended periods of high load, low rpm operation that can cause the transmission to overheat.
RunninOnBlue
New member
Look up the "Deckplate Mod." While I'm not not sure it adds more than 1-2 HP, it seems to help me hold speed in OD on long inclines. My rig won't need to downshift as often.:thumb3:
brian2sun
Elite Member
I don't even understand what you mean there. Once you get up to speed, momentum is moving most of the truck. Burning a lot of gas isn't what is making the engine turn fast at that point. The little fuel being used is just keeping it up to speed which isn't using very much since momentum is working with the fuel. The high rpms aren't making the engine burn significantly more fuel at that point. How far the skinny pedal is pushed down determines the vast majority of your mpgs.
I'm not arguing anecdotally. I regeared my 4runner a few years ago. My 4.88s gears pushed my rpms up about 5-600 at highway speeds. But, I gained 2 mpgs even though I have higher rpms. Why? Because my truck doesn't have to work as hard to get going so it burns less fuel because it's not lagging as much. And once it gets going, the much higher rpms aren't killing my mpgs. That's because at those speeds, the high rpms are mostly passive like I said earlier. Ask anyone whose regeared for weight and/or bigger tires and they'll tell you the same thing - lower gears = higher rpms, but the mpgs will improve. I'm not talking out of my a$$, I'm really just speaking from what I've seen first hand.
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Pikeman
New member
It all has to do with load on the engine. If you have a scan guage you can put it on LOD setting. I have done this and also had the MPG display same time. accelarating RPM 2500 LOD 70 percent MPG 8
maintaining speed at 70mph 2500RPM LOD 18 MPG 20.
I am pretty sure I can swap my scan guage into Brians and get same results at 3000 rpms
take a look at Variable displacement motors or even Hybrids. they use all cyl. to accelerate and then cut down the # of cyl. since it takes less power to maintain speed.
maintaining speed at 70mph 2500RPM LOD 18 MPG 20.
I am pretty sure I can swap my scan guage into Brians and get same results at 3000 rpms
take a look at Variable displacement motors or even Hybrids. they use all cyl. to accelerate and then cut down the # of cyl. since it takes less power to maintain speed.
brian2sun
Elite Member
I think you're correct. I need to get my own scan gauge, those things are awesome!
...
Adder70,
I'm not saying higher rpms don't mean some more fuel consumption. I'm saying the little bit more fuel consumed merely from higher rpms isn't outweighed by the large amount of fuel consumtion you'd have if you ran at higher throttle/lower rpms.
Momentum applies to the engine at any rpm. Momentum doesn't propel the vehicle, it just prevents it from slowing as quickly. The increase in consumption is based on the additional pumping losses and frictions when operating at higher engine speeds.
From Dictionary.com:
Anecdotal (3.) based on personal observation, case study reports, or random investigations rather than systematic scientific evaluation: anecdotal evidence.
I never said there was no condition where the rpms and load are too low and you should downshift. If that were the case, you would never need lower gears. BSFC maps show that lower rpms and higher throttle almost invariably yield better efficiency. The closest engine I could find to the 3.4 is the Toyota 3.0 (1MZ-FE) which is shown to be a bit less biased toward low rpm - high throttle efficiency, but it's still clearly a better bet to use more throttle and lower rpms.
The regearing is probably showing its benefits most during standing starts. This is a high load condition where the higher gearing would result in much more transmission slippage, where energy is used to create transmission heating, not forward motion. So yes, here the lower gearing would absolutely create much better efficiency that could compensate for slightly less efficient highway operation.
BSFC from a Toyota 3.0L SI 4-stroke in two configurations picture by br1ian - Photobucket
