New 4Runner - minor transmission quirk and stinky new engine, anyone else?

Good thing I came across this because I was starting to get worried! Thought something was burning in there lol.

 

The authors of posts 27 and 28 have described it exactly as it happens. Much better than I have been able to.

I’ve been driving automatics, dcts, and manual cars since the 90s and this is the first vehicle that I have noticed to do this on its own. Maybe it’s happened before and it never registered or I just didn’t care.

 

With the 4runner being a “lifestyle” type vehicle, perhaps the engine braking is intended to be a feature that enhances “off-road” and mountain driving capability.

OR… being a 5000lb vehicle, they implemented the feature to help avoid catastrophic overheating of the brakes when newbies don’t know that you shouldn’t be riding the brakes through the mountains.

 

If I were driving through the mountains, I would be in S4, or S3 when climbing. It seems to be easier on the engine and transmission if you keep it in a lower gear, rather that waiting for it to struggle and downshift on it's own. I usually bump it into S5 on descents, unless I want it to engine brake.

 

The automatic transmission is mind boggling in its complexity. The vehicle knows you're going downhill and will downshift because of one-way bearings/clutches inside.

I was looking through the service manual and found a few more interesting pieces of information:

1)

"The ECM memorizes the control conditions of the automatic transmission assembly and engine assembly. Therefore, when the
automatic transmission assembly, valve body assembly or any of the shift solenoid valves has been replaced, it is necessary to
reset the memory so that the ECM can memorize the new information."

After the reset you are supposed to perform a road test and "teach" the ECM

"The ECM learns through the Road Test."​

2)

The transmission tracks and estimates for thermal degradation of the transmission fluid:

"If either of the following conditions is met, perform ATF Thermal Degradation Estimate Reset.

• The ATF has been replaced.

HINT:
If 50000 or more is displayed for the Data List item "ATF Thermal Degradation Estimate", thermal degradation of the ATF
is suspected. Perform ATF Thermal Degradation Estimate Reset after replacing the ATF.​

• Approximately 50% or more of the ATF has been replaced during a repair of the transmission or a similar operation."

​

 

I live in the mountains, all pavement. When driving out of my house, right away I need to go up and down the mountains. So, I tried to eliminate the strain on a cold engine and successfully I got rid of the lag with the Pedal Commander. Going off-road I turn the PC off.

 

Someone posted some of the “throttle mapping algorithm tables” (no idea what they’re really called) on Tacoma world awhile back. Really neat stuff (and complex, as you mention).

 

I think what you’re describing is Toyota’s patented “Grade logic braking system”.

https://www.freepatentsonline.com/9676388.html

If it detects a downhill grade, no accelerator pedal, speed accelerating, brake pedal applied, it will downshift.
Then if the speed slows down by some amount, or the grade is not so steep, or you release the pedal for some amount of time, the transmission upshifts.

The logic looks like this:

 

I find that if I can’t lean into the throttle and easily accelerate from 60mph on grades, then a downshift is in order. Not because I want to move faster, but because the engine feels happier. That mushy 2” of pedal travel without much throttle response just feels wrong. I understand what’s happening (it’s mapped for economy), it’s preventing you from dropping a gear. But if you push hard or far enough, it WILL drop a gear. I think PC eliminates this lag, if I understand correctly.

 

I trust you’re spot on. Will it also do this in S-modes? Or just when in D?

 

I don’t drive in S-mode for very long so I’ve never noticed. But I imagine it should behave the same way. It’s worth experimenting to find out.

 

Yeah, it's not hard to get it to downshift on it's own if you give it some gas. I prefer using S mode because it's easier on the engine and transmission, like you said.

 

Interesting, nevertheless, doing a Google search on similar patents, any major automotive brand has similar patents & applications under different names; some might be less effective & others more effective.

 

Yes, this is correct, the PC eliminates that lag. I still try to find a serious reason why Toyota didn't do it the way the PC shifts. Seriously, the mileage is not really affected, sometimes you have better mileage, depending on the mode you are driving. The City mode gives you better mileage. Sport & sport + gas consumption is higher, not by much.

 

I think Toyota gave the pedal a lot of play to make it easier to make fine adjustments. I think the only reason it downshifts more readily with a PC is because of the amplified signal from the pedal. None of those devices can actually change the shifting patterns, as far as I know.

 

Yes, the concept isn’t new and other autos have similar systems. I’m not sure what is so unique about the Toyota implementation that they needed a patent. Maybe using sensors that detect the degree of grade or the particular accelerometers in their algorithm. One thing they hinted at in the patent language is the Toyota system does not disengage if the engine RPMs get very high, like other manufacturers. The Toyota priority being to save the passengers, not the engine.

I think it works well whenever I've experienced it downhill on steep highway grades at speed. What drives me crazy is the other feature of transmission control where it takes so long to upshift after cresting a hill and after the load decreases. This also is nothing new for the 5th Gen. You can read forum posts from 10 years ago complaining about this. Nobody seems to know why Toyota hasn’t tweaked this to upshift sooner.

 

Didnt read any of it,...


Its fine. Go for a ride/adventure.

 

I don't know if you have driven a 4R with the PC, I believe as well the shifting patterns are hard coded in the ECU. Nevertheless, upshifting is much faster as is downshifting with the PC, smooth & no lag. I think it might be true what is said on different websites that the throttle body is opening faster, (I assume that the throttle body is controlled by the ECU in the 4R.) I don't know how the PC would make chances to the ECU. There must be more to the control board of the PC that I don't know; maybe someone else here on the Forum knows.

 

I think Lawsuit protection. Most large companies have more patents than useful components.

Exactly, mystery to me as well.

 

It would be interesting to do some side by side comparison with 2 stock 4runners to see if there's actually a difference. I have heard from several PC users that feel it changes the shifting behavior, but I don't see how it's possible.

I have no issues with how mine shifts or accelerates. But, I have learned that you need to put it to the boards to get it to move.

 

I does change the shifting behavior, guaranteed. It's easy to feel, the difference is extensive.

For me in the mountains, straight out of my garage; I have to put the pedal on the metal, sure S mode works better for this; still, I always had that idea or feeling, that can't be good for that cold engine. Maybe it's just me , being old and always told more than a half a Century ago that it was bad to rev a cold engine.

 

How, though? The shifting is controlled by the ECU. All the PC does is amplify the throttle signal to the ECU. I would bet that a stock 4runner with more pedal applied will shift exactly like a PC equipped 4Runner.

How is flooring the throttle any better than using S mode to keep the engine in it's power band? If you need to drive aggressively right out of your driveway, you might want to let it warm up a bit before you take off.

I'm not suggesting that it doesn't improve the driving experience for some. But, it's not possible for it to change the shift patterns. It probably appears to because it sends an amplified throttle signal. Turn the PC off and give it more gas. I bet It will shift the same.

 

It's hard to debate something, if the other party hasn't tried it. I think there is more involved than amplification to the throttle signal.

I didn't say that flooring the throttle is any better than using S mode? I don't want to drive aggressively at all with a cold engine, that was my point. I did not like the lag, for sure on an incline and with a cold engine. Taking off on leveled pavement is no problem, you still have lag, that is something we know buying the 4R, which is fine for me.

I didn.t say it changes the shift patterns; I said it does change the shifting behavior, the lag is gone and the shifting is much smoother. I don't have the technical answer why, just the experience driving the 4R without & with the PC.

Power Commander engineering department have the answer, will they tell us exactly how it works, I don't think so. just my 2c.

 

Top-fuel alcohol? Try a different gas station. Temps, elevation has a lot to do with it.

 

I had a 2006 Sienna with a 5 speed auto that had the same downshift logic. If you are going down a long downhill, in D, and you put slight pressure on the brake pedal for some amount of time, it drops down a gear and holds it for the duration of the hill. It provides enough engine braking to reduce the amount of braking needed to manage your speed.

It’s very nice if you appreciate the “squared” physics of going down hill for extended amounts of time with excessive speed, and how hard it is on your pads/rotors to scrub off speed in those situations.

I recall having read about it in the manual, but honestly, I thought it was magic when I first experienced it in action. I got all excited and had to show it off to my dad lol

 

You are correct about this!

I fully believe it wakes up the 4Runner and improves the driving experience for some. I also do believe that it reduces the throttle lag. But, I don't see how it could affect shifting "smoothness". I don't have one and mine shifts like butter!

 

I’ve never bought a Toyota truck because it was fast.

 

Neither did I.

 

PC and SB do essentially the same thing: installed between the accelerator pedal and the engine control ECU they amplify and change the curve of the two accelerator pedal output signals to the ECU so they reach full scale output voltage sooner. In user selectable increments. Several threads on this forum and the T4R forum explain this in more detail.

They don’t directly do anything to the throttle body or transmission shifting behavior. That’s the job of the ECU. It really is like amplifying your foot movement on the pedal, so the truck reacts faster to your foot. And it results in a more enjoyable driving experience. I’ve used a Sprint Booster on my 4R for over 3 years and it’s one of my favorite mods.

 

It's hard to describe, for me it feels like that gap (lag) space in between going from one gear to another is gone; I don't drive in sport + mode, I drive in sport 3 mode. To me It doesn't feel like amplifying my foot movement, feels more like the power is always there, the 4R drives different, I'm gentle on the throttle and it reacts much better not brutal, it feels just right . Pfff, I need to mail one to @Thatbassguy than we can have a good debate & proper evaluation.