Overland Torque Tune (OTT) by Overland Tailor

I shot the account an email. I just found out about OTT today and was extremely disappointed that a TCU tune isn’t available for my 2017. The trans/gearing is the biggest downfall of the 5th gen and I would LOVE to rectify it with the OTT ECU and TCU tune

 

Send that email and tell everyone you know with a 2013-2019 T4R to do the same.

 

Is it possible that the gearing itself is the issue, and tuning wouldn't be much help?

I'm interested to hear what @JustDSM has to say about this.

 

People that have the TCU TUNE (pre 2013 and post 2020) said it drastically changes how the 4runner drives

 

I don't know if it drastically changes it....but it's an improvement for sure.

 

That's a much more complicated question than most might realize. Sure, you can look at it in a simplified form, but there are a lot of critical details and nuances that (in my opinion) shouldn't be glossed over.


Let's take a moment to explain why you're seeing the shift behavior you’re experiencing, and why certain modifications (like changing ring and pinion ratios) can affect it, especially since aftermarket tuning to adjust shift points isn’t yet available on your particular year model.

Your vehicle’s transmission uses output shaft speed (OSS)—the rotational speed of the transmission’s output shaft—as a primary reference for deciding when to shift. Essentially, the transmission monitors OSS and accelerator pedal input to decide when to shift up or down.

• Output Shaft Speed is tied to transmission/driveshaft rotation, not vehicle speed.
• The transmission doesn’t directly "know" your vehicle’s speed when deciding to shift—it simply responds to how fast the output shaft is spinning.

When you change your ring and pinion to a higher numerical ratio (for example, going from 3.73 to 4.88 or 5.29):

• Your axles spin faster for every rotation of the driveshaft.
• This means that for any given vehicle speed, your transmission’s output shaft is now spinning faster than before.

Because your shift tables are tied to OSS:

• The transmission now reaches its programmed shift points sooner in terms of vehicle speed.
• This causes the transmission to shift earlier than before, not because the shift strategy changed, but because OSS now climbs faster relative to road speed.

In practical terms:

• You’ll feel shifts happen at lower vehicle speeds than before.
• The engine may feel like it’s being shifted early or unnecessarily often at lower speeds.

Ring & Pinion vs. Tuning: How They Compare

Tune:

• Improves engine torque output and throttle response.
• Helps the engine feel stronger without increasing RPM.
• Can refine shift behavior once shift tables are adjustable.

Ring & Pinion Change:

• Changes the mechanical drive ratio – amplifies torque at the wheels.
• Forces the engine to operate at higher RPM at any given speed.
• Causes the vehicle to shift earlier (lower vehicle speed) unless shift tables are recalibrated.

Combined, a tune and gear ratio change can work well together:

• The tune improves engine-side torque delivery.
  
• The ring & pinion enhances mechanical advantage to the wheels.
  
• Together, they improve both responsiveness and drivability—especially at low speeds or when under load.

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If your vehicle feels like it’s shifting too soon or isn’t holding gears long enough, this is a result of the OSS-based shift logic not being aware of the ring and pinion change. Until shift point tuning becomes available:

• A more moderate gear ratio (like 4.88 instead of 5.29) may be more balanced.
  
• The tune can help improve torque output and reduce the need for frequent downshifts, working with your gearing rather than against it.

Once shift point tuning is possible, we’ll be able to directly correct for this by adjusting OSS targets to restore proper shift timing relative to your new axle ratios.

 

The ECU tune alone changes it drastically
I dont have trans tuning, in their email i specifically told them how disappointed i was in how the trans shifted, it wont hold any gear on any highway even on flat ground. Its always hunting for gears, overdrive is useless, ect ect. They told me they couldnt "guarantee" anything about how the trans shifted but their tune would help and they were right. The 4R drives so much different, like it was supposed to be from the get-go. Just get the ecu flash and i assure you the trans will act better than it does now.

 

Excellent! Thank you for sharing.

With our tuning, we're able to effectively generate more torque for a given pedal input, which can significantly improve the driving experience even if the transmission shift points aren't adjusted. The fact the vehicle can now produce more torque before executing a downshift really extends the effectiveness of the factory mapping. Doesn't fix it completely! But it can (as quoted above) make a difference.

 

If you re-read my post and the ones I was quoting, I was not the one concerned about transmission behavior. I know why mine down shifts all the time.

 

The attitudes on this forum are something else.

 

I'm sorry. I shouldn't have come off so snarky.

Honestly, though, I'm not dissatisfied with the the behavior of my transmission, especially considering the amount of extra weight I'm hauling. Ideally, I should be regeared, and I've considered a tune as well. A few extra HP would be nice.

 

I'm sorry if I missed this in the thread but, do you need to update anything with the flash if I were to re-gear to 4.88?

 

yeah, I guess you’re right. And my closest retailer/installer said the TCU tune (if and when it comes out) will be a free update. I guess I’ll go ahead and schedule to get the ECU tune