First offroad, el. 13,124’ [Summit County, CO] - Compare/Contrast 5th Gen 4Runner

[b407driver]

Okay so if you guys wouldnt mind helping me here… im relatively inexperienced to these functions on toyotas; i have lots of experience with engine breaking on my previous F150 when towing a 28’ travel trailer and I used DAC a few times driving downhill trails in oregon (not towing of course).

Is there a reason we would use Engine breaking vs DAC on a slow downhill crawl?

I think comes down mostly to driver preference, especially what someone is used to. I rarely used the Crawl Control on the 4Runner due to the jerkiness and the noise, and thus am used to manually controlling the vehicle. For people who have always had these electronic systems and used them, they might be more likely to use them frequently. For others, keeping control via shifting manually might be better, especially in variable terrain where speeds don't need to be held constant.

Technically speaking, the DAC system is probably better than a human in controlling the brakes and limiting wheel drag (I'm sure some would argue this), but only on a pretty severe descent would anyone likely notice a significant difference. And admittedly, driver skill certainly works into it. Using DAC would free you from having to manage RPM so you can concentrate on steering, but as mentioned above could also limit your speed unnecessarily when the terrain might dictate you can go faster.

I mentioned Red Cone, a fairly technical descent here in CO where mis-using the brakes could certainly get you into trouble. Using DAC on robust descents like this could be very helpful, especially for less-experienced drivers.

 

[b407driver]

It definitely changes over time. I’m just under 4,000 miles and it has slowly used more and more hybrid and running for longer periods on battery, I had a few miles of light load driving on mostly flat at 45 MPH entirely on battery this weekend, was really surprised, and the MPG keeps improving. Got an estimated 25.5 MPG yesterday on a 50 mile trip ranging from state forest road, back roads, steep mountain climb and decent, hilly, and interstate between 65-75 MPH.

That's great to hear, I hope mine follows your experience. Yesterday was the very first drive where I averaged over 20, but that was descending I-70 from Summit County to the flatlands. Been around 15-16 so far, but still have just under 500 miles on the odometer, almost no freeway driving.

 

[Altitude]

Excellent post and it’s fun how over represented Colorado is on this board.

Mine won’t arrive until about Thanksgiving but I am keen to explore the engine braking (please, not “breaking” which means something entirely different) situation. My commute between our homes is Castle Rock to Avon, which means I go all the way up and all the way down big long grades four times each trip. I admit I’m a little obsessive about engine braking.

Convinced some of the differences people feel might owe to the number of gears versus whatever you drove before. I used to have a 2004 Explorer with a 5 speed, and my current Tahoe has a 6 speed. Making the significant assumption that the final drive gear is roughly the same across all of the vehicles, a single gear downshift would result in substantially more perceived engine resistance on the Explorer than the Tahoe, and more on the Tahoe than the LC. To wit, my wife’s GLC300 has a 9 speed transmission and I feel like I have to drop it three gears to feel much change in the driveline resistance. Similar my 991.1, which has the 7 speed PDK.

Obviously RPM doesn’t lie; we want to get these to an RPM level that yields the desired braking effect, whichever gear that happens to be.

I’m looking forward to seeing how the regenerative braking fits in to this.

(For you guys who live in places without mountains and have no idea what we’re on about - those “runaway truck” ramps you see on the highway on your way to the ski resort are mostly for semi drivers who use their brakes too much and their transmissions too little on these long descents. Their brakes get too hot to function and they have to bail.)

 

[rjmh]

Okay so if you guys wouldnt mind helping me here… im relatively inexperienced to these functions on toyotas; i have lots of experience with engine breaking on my previous F150 when towing a 28’ travel trailer and I used DAC a few times driving downhill trails in oregon (not towing of course).

Is there a reason we would use Engine breaking vs DAC on a slow downhill crawl?

We used the DAC a fair amount over the weekend. I found it effective and easy to adjust speed with the dash knob. I turned it off on a long steep downhill when I started to smell the brakes, and manually down shifted from 3 to 2 to 1. I don't have an opinion on how effective the engine braking is relative to other vehicles, but it is certainly present and it certainly let me brake and release. I would agree that engine braking alone was not sufficient to control the speed, and I did miss my sprinter's paddle shifters. So yeah the reason is to be able to release the brakes as opposed to having them continually on.

 

[DenisLM]

On the way up, I was watching the turbo and hybrid gauges, just to see how this new drive system would handle the high-altitude climb (more variables than a simple IC engine). I was quite surprised to note that below ~12,200’, the turbo and hybrid system rarely kicked in, only when needing to get up a short, very steep portion of the trail, and only very briefly. Considering the considerable elevation and temps (60-55°F), this surprised me. Also, about halfway up the hybrid battery was nearly at max SOC, ~7 bars; (started at 4 bars). At around 12,500’ the turbo started kicking in, and from then on did so pretty regularly, as needed. This seems odd to me, as there wasn’t a big change in terrain that should have warranted it. The hybrid only really kicked on for a second or two max, never for any extended period. This also surprised me. Fuel economy on the way up? 5 mpg.

I'm curious if you observed the transmission temperature after all this climbing.

 

[b407driver]

I'm curious if you observed the transmission temperature after all this climbing.

I did not. Instead of perseverating over a gauge that may or may not accurately reflect relatively small incremental changes, I instead drove it and hoped not to see the transmission temp error message. Fortunately, I did not.

 

[b407driver]

We used the DAC a fair amount over the weekend. I found it effective and easy to adjust speed with the dash knob. I turned it off on a long steep downhill when I started to smell the brakes, and manually down shifted from 3 to 2 to 1. I don't have an opinion on how effective the engine braking is relative to other vehicles, but it is certainly present and it certainly let me brake and release. I would agree that engine braking alone was not sufficient to control the speed, and I did miss my sprinter's paddle shifters. So yeah the reason is to be able to release the brakes as opposed to having them continually on.

That's a great take that I ignored in lieu of going into details beyond the advantages of not wasting brake pad. Thanks for posting!

 

[DenisLM]

I did not. Instead of perseverating over a gauge that may or may not accurately reflect relatively small incremental changes, I instead drove it and hoped not to see the transmission temp error message. Fortunately, I did not.

Looks like you kept 4LO on most/all the climb and if so the higher rpms in theory kept the temperatures more controlled.
At least this have been my experience.

 

[b407driver]

Looks like you kept 4LO on most/all the climb and if so the higher rpms in theory kept the temperatures more controlled.
At least this have been my experience.

Nope, 4High for the climb, 4Low for the descent. Didn't engage 4Low on the way up at all. I just edited that first 4High statement to make it more clear. Thanks!

 

[Colorado]

That photo of your skid plate makes me change my thinking. Now I've got to ditch my cheap plastic one and go with the FE's much more rugged version.

You're going to cost me money!

 

[b407driver]

That photo of your skid plate makes me change my thinking. Now I've got to ditch my cheap plastic one and go with the FE's much more rugged version.

You're going to cost me money!

Ain't me, it's this forum!