Driving my Pro at guest speeds

I have a new 2023 Pro. At guest speeds (80 mph) it continually shifts into and out of passing gear. What is the best fix?

 

What exactly are "guest speeds?"

 

Welcome.

 

Sorry should b hiway speeds (80mph)

 

Slow down.

 

Bump it over to S4 and it will lock out the overdrive gear. MPG will take a hit. Seems excessive driving at high RPM’s like that. But I don’t know how it’s much different than towing a heavier load at a slower speed. The engine wouldn’t know the difference?

 

My guess is it's not actually shifting from 5 to 4, but is locking / unlocking the torque converter in 5th.

Agree with the others, you'd be happier driving it a little slower. If this is your first 4Runner, you can expect to do everything slower, lol.

 

Thanks for the advice. To introduce myself, this is my first 4 runner after 3 Outbacks. Love the Pro but driving I-85 in Ga you must keep 80+ just to Avoid being run over.

 

Oh yeah, I hear you, used to live in Atlanta. I'd happily drive 75ish mph, but it seems like the options there are under 60 in the right lanes, or get out of the way on the left.

If the RPMs are moving by like 2-300 (I think), then it's the torque converter lockup. You will know when it drops to 4th at 80, I think it's over 3000 rpm, and would be a bit noisier.

 

Interesting. I assumed it’s jumping between gears, searching for the right one. Annoying and why I rarely use cruise control.

what’s the purpose of the torque converter?

 

Yep 4th should be about 3100-ish at 80mph. More with some wind.

The truck could easily be dropping to 4th with a headwind at 80mph. Like you said, it’s more jarring than the slip of the torque converter

 

When I lived in Atlanta, breaking 10 mph on I-85 was cause for celebration. Things must have improved. (And this is my first 4Runner after 2 Outbacks).

 

Georgia is weird. Strict speeding laws, but people drive like maniacs.

At 80+, it's going to be downshifting a lot. They are geared for fuel economy, but this backfires at higher speeds because it's a big, heavy rectangle with a V6 that some consider underpowered.

A tune might help a little. A supercharger would help a lot.

Otherwise, your best bet is to deal with it.

Welcome to the forum!

 

More or less it’s the automatic transmission version of a clutch. The torque converter is the coupling point between the engine and transmission. If they were bolted directly together the engine would stall every time the vehicle stopped. The torque converter transfers power from the engine to the transmission via fluid. The toque converter clutch mechanically locks the input and output side together for direct 1:1 ratio. When it’s unlocked there is always some loss from the input to the output.

 

So what exactly is happening in our trucks in 5th gear at 80mph when you can feel the torque converter doing it’s thing? I watched YouTube videos and still don’t understand… is it simply acting like a clutch between 4th and 5th? Or is it like a 4.5th gear?

Or might it re-lock and run 1:1 on, say, an uphill grade, and then unlock once you hit flat ground again?

 

You slowing down and speeding up? Trying staying at one speed. It won't do it if you stay at one speed. Unless the road isn't flat.

 

I don’t actually know without seeing it in person, but it sounds like second part. The clutch is locking and unlocking which will cause minor rpm changes.

 

It’s a dog of an engine. I’d just slow down.

 

I found that if you put it in S5 the transmission hunting seems to stop. It will stay in fifth gear longer and shift back to fifth gear faster from 4th when going up hill is what I’m seeing. When I’m in drive mode when going up certain hills it would shift down to 4th and than it would shift out of 4th to 5th until I would be going back down the hill. When in S5 I don’t have a problem with this shift. When driving the turnpikes and down 95 to Florida I’m between 78-82. 2019 Pro, 17-20 mpg

 

So do 85 mph and keep the rpms up You won't get good fuel economy unless you keep it below 70 mph, so don't even bother.

Find a "tuner" in your state or neighboring state and get a tune flashed on the ECM (for example I used OTT), the engine will be more rev happy and feel less labored above 3000 rpms.

 

I use the sprint booster in mine and literally can't drive without it. The sprint booster makes it much more enjoyable experience. That being said, I've just accepted the fact that this is a 65-70mph highway vehicle. Just finished a 700 mile round trip to visit my brother in Pennsylvania. Half the trip was pretty hilly and by keeping it at 70 or below, I was a low to average 21mpg in my stock TRD PRO.

 

Lockup is like gear 5.1. It's used under lighter loads, so if you climb a hill the torque converter is acting normally (open), then when it's flat it will likely lock up and drop rpms just a little.

 

S5 It’s definitely worth trying. Also if you have the pro roof rack it adds a lot of drag. It’s not much at lower speeds, but at 80 mph, it’s going to act more like a parachute. It might be worth taking it off if your 4runner does a lot of commuting duty. Your mpg will also increase at those speeds with the rack off.

 

It's not really a gear at all. Let's say you're driving your truck at 70 and the torque converter is locked in 5th gear. Engine is at 2000 RPM. Essentially, your engine output speed is linked directly (mechanically) to the wheel speed.

Now let's say you want to increase the speed to 80 and there's additional aerodynamic load. The truck has two choices: it could downshift to 4th gear and lock the TC again in order to place the engine in a more suitable part of the powerband to make the required torque for the new load, let's say 3500 RPM.

Or, it could stay in 5th gear, unlock the TC and push the revs up that way. Your engine surges to 3000 RPM, though because the TC is unlocked the driveshaft(s) are only seeing an effective 2500 RPM from the trans. Basically, the TC is a fluid coupling/turbine that can control how much rotational energy is being transferred to the gears/driveshaft(s). It controls this by allowing pressurized trans fluid to "leak" out of the coupling back into circulation. When it doesn't let fluid leak out of the coupling, the input/output speeds are in sync and most modern transmissions have a mechanical lock to minimize the need for pumping all that fluid.

Modern computer controlled vehicles will make this "choice" based on programming and prediction. Are you raising speed/load temporarily, as if to pass another vehicle? Or are you heading up a long grade and will keep this speed for an extended time? You can influence this choice with manual shifting (different cars have different amounts of true driver control when manual shifting an auto trans).

The clutch analogy is useful, think of using one to slip so that the engine is revving higher than the input shaft. Of course, dry clutches are only meant to do this momentarily at zero speed starts and gear shifts. If you used one the way you use a torque converter, it would burn up the clutch in short order.

However, torque converters aren't invincible either. That cycle of pressurizing fluid and letting it leak out of the torque converter for dissimilar engine/trans speeds (TC unlocked) generates heat in the fluid, which can be detrimental if you operate this way for too long without being able to shed the excess heat. This is why most towing packages (or purpose built trucks) have extra coolers for the trans fluid, because you will have a lot more speed and load variation than regular passenger vehicles.

It is also why it's a good idea to shift into 4-LOW for low speed off-road driving, even if you don't need the extra torque or traction. If you are traveling at speeds lower than the first gear lockup speed, your torque converter will be working overtime to pressurize and leak that extra fluid so that your engine can spin faster than your wheels, even at idle speeds. If you're in 2HI or 4HI and find yourself riding the brakes most of the time to modulate speed, you're adding undue wear and tear to both your brakes and your transmission fluid. The fluid should be considered a consumable just like your engine oil, more heat cycles will break it down quicker. Shift into 4LO, you will put less stress on the vehicle for low speed operations. Many tame off-road trips have been slowed or ruined entirely by overheating automatic transmissions.

 

As best I can tell, 5th/overdrive is 0.716:1, based on information obtained from another forum in. Otherwise, you're correct.

Here's what I found:

Gear Ratios
1st 3.52
2nd 2.042
3rd 1.4
4th 1.0
5th 0.716
Reverse 3.224

Edit: unless you meant that it's a gear higher than 5th, which is not correct. It's just 5th gear with the converter locked.

 

Thatbassguy, you're right. What I said is not really accurate, but that's how I think of it at least, since it has a similar effect (lower RPMs, less torque, etc.).

 

I also have a 23 TRDP and have never experienced this issue at that speed and faster (other than when the truck is fairly loaded and going up a hill in cruise control where I can instantly make the hunting stop by cancelling the cruise control). You didn't provide more info/details for us to give a better assessment, but my first thought is it doesn't sound right .....

 

Running premium solved my hunting issues, including cruise control

 

I live in a similar type area. I avoid this by not trying to maintain the exact same speed. I let it fall a little up a grade and speed up down grade. Not dramatically, but enough to where I'm not forcing as many downshifts. I do commonly catch 4.5 (using thread terminology). It's the polar opposite of how I drive my Camry, where even a light throttle pressure it wants to drive 100.

If it's really an issue a tune might be the easiest thing to add power, but I dont know how much difference it would make since NA engines make the most power upper in the RPM, and we're talking about the 2K range on the interstsate. The new 4th gen Tacoma powertrain will probably be a lot better in this capacity with the turbo and 8 speed.

 

Interesting. Thanks for sharing. Altho running 87 was a major draw for the 4R!