Has anyone figured out a solution to the excessive downshifting in cruise control

[Charles Bronson]

Has anyone figured out a solution to the excessive downshifting from 5th to 4th in cruise control? One of my biggest gripes with these 5th gens is the TCU's insistence to downshift from 5th to 4th while in cruise control and dealing with slightest grade. If you're not in cruise control, you can slowly press on the gas and more often than not, the torque converter will unlock in 5th and the TCU won't downshift in 4th. For whatever reason, the TCU doesn't want to unlock the cruise control while in 5th and cruise control engaged. Either the TCU is looking at the increase in engine vacuum or the slight speed change thus goes hyperactive and downshifts. It's so silly and quite annoying.

I was just curious if anyone has figured out a fix after all of these years.

 

[DAW89446]

Used to annoy me also after I bought my '18. Would kick down even going over an overpass. What was worse is that it wouldn't shift back up going down the incline on the other side. But with time I've learned to ignore it.

 

[osugsxr]

Has anyone figured out a solution to the excessive downshifting from 5th to 4th in cruise control? One of my biggest gripes with these 5th gens is the TCU's insistence to downshift from 5th to 4th while in cruise control and dealing with slightest grade. If you're not in cruise control, you can slowly press on the gas and more often than not, the torque converter will unlock in 5th and the TCU won't downshift in 4th. For whatever reason, the TCU doesn't want to unlock the cruise control while in 5th and cruise control engaged. Either the TCU is looking at the increase in engine vacuum or the slight speed change thus goes hyperactive and downshifts. It's so silly and quite annoying.

I was just curious if anyone has figured out a fix after all of these years.

there is a 4runner tuning groups throughout the US. Search tacoma tuning as well. Think its OTT itll optimize the ECU and TCU to eliminate sluggish factory throttle response, reduce gear hunting, and improve overall drivability. I looked into it years ago but didnt bother.

 

[fourrunnerbill]

if the incline or decline is steep I just temporarily turn it off. I prefer to allow the vehicle to slow down a bit on hills anyway. Better fuel economy.

 

[MZ2215]

I haven't but hope someone does. Have a ~3 hour drive I do a dozen times a year with the 4R loaded up with family and weekend worth of clothes and gear and I've just learned where I have to turn it off so it doesn't kick down a gear or two. Have found that if I drive closer to 80 than 70 it's less frequent, I assume because it's more in the meat of the torque curve, but the gas mileage seems to get exponentially worse as speed increases and i'm not a big fan of tickets so I like to keep it 73-75mph.

 

[Jeff_DML]

It drives me crazy too but I just assumed it was because the lack of gears and gutless v6 and deal with it. I don't like how it downshifts and over corrects then is going too fast.

 

[Yamahamer]

Every gas-powered vehicle I've owned has had the same problem. And its caused by not enough torque at the low rpm the engine is running at in overdrive to maintain the exact speed set on cruise. My diesels on the other hand, with maximum torque at 1400-1800 rpms, NEVER need to shift down.

 

[02SE]

Every gas-powered vehicle I've owned has had the same problem. And its caused by not enough torque at the low rpm the engine is running at in overdrive to maintain the exact speed set on cruise. My diesels on the other hand, with maximum torque at 1400-1800 rpms, NEVER need to shift down.

Yep, not enough torque at the low RPM the engine is running at in overdrive, to precisely maintain the set speed in overdrive, without downshifting to bring the engine RPM up enough to where it does produce enough power to maintain the set speed.

Larger more aggressive tires, racks, lifts, additional weight added to the 4Runner, all exacerbate the issue.

 

[gordonp]

Re-gear your diffs to 4.56

Test it out by moving your shifter to S(port) 4. This is what it'll be like if you spend C$5k and have 4.56s installed by a shop (as far as increased highway rpms).

Best move I ever made. 4500lb trailer tows like a stock unladen 4Runner, and I can even speed up when encountering modest highway hills, without a downshift. Heck, my ECO gauge now sits mid-scale on a level highway when towing!!

Around town, it's nice-and-snappy.

Offroad is beautiful.

Once nice thing, compared to the olden days: no need for speedometer correction. Apparently our Gen5 derive the speed from the ABS tone-rings, thus only a tire-size change will affect speedo, not gearing.

 

[Charles Bronson]

Every gas-powered vehicle I've owned has had the same problem. And its caused by not enough torque at the low rpm the engine is running at in overdrive to maintain the exact speed set on cruise. My diesels on the other hand, with maximum torque at 1400-1800 rpms, NEVER need to shift down.

Yep, I wish Toyota would have used really long intake runners and/or different cams to trade some upper rpm HP for some much needed lower end torque. Better yet, they should have installed the 6 speed automatic from the Tundra and regeared the differentials a bit deeper. MPGs and acceleration would have improved to.

Over the weekend we were driving through northern Missouri and Iowa which have lots of long, rolling hills. The wind was light. There is no rhyme or reason as to when the transmission decides to hold the gear, to unlock the torque converter in 5th (rpms increase around 400rpm), or the transmission downshifts to 4th to handle the grade. Same grades, same speed, and all different approaches to how the transmission decides to behave.

I would bet that if we had all season light terrain tires on the truck, it probably wouldn't downshift as much and get 2mpg better mileage. BUT my wife likes the look of AT tires (C load is what we run) so that is what it has even though the only off roading the thing sees is occasional gravel roads and snow driving. LOL

 

[premise]

Yep, I wish Toyota would have used really long intake runners and/or different cams to trade some upper rpm HP for some much needed lower end torque. Better yet, they should have installed the 6 speed automatic from the Tundra and regeared the differentials a bit deeper. MPGs and acceleration would have improved to.

Over the weekend we were driving through northern Missouri and Iowa which have lots of long, rolling hills. The wind was light. There is no rhyme or reason as to when the transmission decides to hold the gear, to unlock the torque converter in 5th (rpms increase around 400rpm), or the transmission downshifts to 4th to handle the grade. Same grades, same speed, and all different approaches to how the transmission decides to behave.

I would bet that if we had all season light terrain tires on the truck, it probably wouldn't downshift as much and get 2mpg better mileage. BUT my wife likes the look of AT tires (C load is what we run) so that is what it has even though the only off roading the thing sees is occasional gravel roads and snow driving. LOL

Looks kill! Fashion over function tax.

 

[1000MPH]

I use CC a lot, but on a typical 400 mile drive I’ll cancel and reset it about 100 times. I also use sequential shift or “S-mode” anytime I’m in the mountains or hill country so I can slip it into 4th or lower before it bogs or whatever. Also to keep Grade Logic from downshifting prematurely on descent. I hate that!
Gotta find a way to use the tools ya got.

 

[Turfboy]

Just made a camping trip to the Oregon coast( fully loaded up). The supercharger has a bypass that prevents the supercharger from working unless vac goes away. My ultra gauge blue reported the supercharger working through many of the rolling hills we went through without downshifting. Average mpg was 20 at 70 mph. Downshifting occurred when MPG dropped to 10 and boost was between 5 to 7 psi. Trannie temp was averaging 185 in 95 degree weather and pegged 224 degrees up the Pendleton grade (99 ambient temp).

It may be an extreme solution but if you are bugged by downshifting go with the supercharger :thumb:

 

[Trumpet]

Happens even when not using Cc.

I put a banks pedalmonster in a couple years ago. I tow alot usually lock the trans in 4 and keep it 65 and under on the highway. The banks keeps the torques steady and the shifting to a minimum. For towing I use the midrange setting at 4, for general commuting in the Torque range still at 4.

Average 15 mpg towing a 7x12 v nose, and around 20 commuting. I see a lot of elevation changes from home base.