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Hey there. I've been thinking of getting a Toyota Sienna and am wondering how it stacks up against other AWD vehicles, such as the Subaru Outback or Toyota RAV4. I would use it for (backcountry) skiing, mountain biking, and climbing so it'll need to handle dirt roads with loose gravel and powder on hardpacked snow. I see there are lift kits that could help the ground clearance situation, but what good is a lift if the AWD sucks? Anyways, I guess this is a little broader than "other minivans" but this seemed like the most appropriate sub. Any insight would be much appreciated. Thanks!
 

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I can confidently say it is better than a FWD van with an open diff, but not as good as a Jeep with lockers.

In seriousness, it struggles a bit in this AWD intelligence test but the system eventually figures out where to send power and gets the job done. That’s the best evidence I can come up with.

Jump to 52 minutes:

 

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We have an Outback.
We had a FWD Sienna, and replaced it a year and a half ago with an AWD.
The AWD Sienna is a considerable improvement over the FWD Sienna in snow.
With Blizzaks the AWD Sienna is highly capable.
We live in rural upstate NY at the top of a long curving hill.
Our old Sienna would struggle on snowy days. The AWD eats it up.
We also back country and downhill ski. We go to remote access points and I have no worries with the AWD Sienna a long as there isn't heaped up snow on the lip of the parking lot, because you can beach it due to the low clearance.
The Outback is still better in really poor driving conditions but not by much.
We are very happy with our AWD Sienna in the snow.
Hope this helps.
 

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Thanks, @cny rider. That was exactly what I was looking for!

Thanks for the video, @Camper Van Someren. You're right, that wasn't very impressive but it got the job done. Hopefully a lift and good pare of tires will help avoid that scenario. Speaking of lifts, I see you put a lift on your Sienna. Do you think that helped with its driving performance on non-paved roads?
 

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Thanks, @cny rider. That was exactly what I was looking for!

Thanks for the video, @Camper Van Someren. You're right, that wasn't very impressive but it got the job done. Hopefully a lift and good pare of tires will help avoid that scenario. Speaking of lifts, I see you put a lift on your Sienna. Do you think that helped with its driving performance on non-paved roads?
I just finished the lift a week ago. We’re taking it to a campsite tonight and I’ll report back. Honsetly I don’t think I’ll notice much difference unless the road is rocky or rutted. Clearance is the kind of thing that you don’t think about until you need more of it...
 

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Here she is out in the woods. There was an uneven rocky section getting down to the campsite, and before the lift I would have been very careful with it, maybe even sent my wife out to spot. Now I have the confidence to just cruise through. Aside from that, it didn’t “feel” any different.

Didn’t need the AWD last night, but pre-lift I have taken it on some steep snow and gravel stuff that would have been nearly impossible without AWD.

Overall, I would say that with this lift it has comparable off-road ability to a crossover like the RAV4 or Highlander, which is to say the majority of new vehicles on the road since everybody seems to be buying AWD crossovers now. If you just need some “soft roading” ability you’d be better off buying one of them since you don’t have to worry about the lift process changing suspension and CV geometry etc. So far nobody has reported failures from a lift but it is a concern in the back of my mind.

The lifted Sienna stands out because while it only has “average” off-road ability, it has more interior versatility and space than any “off-roader” except the Mercedes Sprinter 4x4 which starts at $60K and goes waaay up from there. So if you have kids but also need to hit forest roads, or want to do a small camper-van conversion on a budget, the AWD sienna is a very unique solution.
 

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One thing the Sienna lacks compared to other vehicles within the Toyota lineup (I'm thinking RAV4 and Highlander) is a lock button to keep the rear electromagnetic clutch engaged. My daughters 2018 RAV4 will remain in AWD up to 25 mph (?) with the dash control.

Someone was doing diagnostics and mentioned that a varying pulse width signal was sent to the clutch to vary F to R transfer ratio. I wonder if this couldn't be 'added' by a savvy owner?
 

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Discussion Starter #9
The lifted Sienna stands out because while it only has “average” off-road ability, it has more interior versatility and space than any “off-roader” except the Mercedes Sprinter 4x4 which starts at $60K and goes waaay up from there. So if you have kids but also need to hit forest roads, or want to do a small camper-van conversion on a budget, the AWD sienna is a very unique solution.
That's pretty much my thinking. Plus the Sprinters are way too big (not like I could afford one). If I wanted a vehicle that size I would just get a truck. Thanks for the update by the way. It sounds like it's going to work well for you. It looks good too!

Thanks for chiming in @fibber2. That's a really interesting point about the lock bottom. Do you think that's what we were seeing in the video @Camper Van Someren posted? I'm not too savvy but if it were a matter of swapping a RAV4 computer into the Sienna then I might be able to swing it (assuming it's a Ford Transit Connect / Focus sort of scenario).
 

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It's become tough enough to swap out ECU's of different year vans and not end up with terminally suck on DTC's. Swap a RAV4 (different engine and tranny)? No way. The Highlander is generally a closer match, but still I'm going to say probably no. Not without some custom code modification.

I think the better approach would be to generate an appropriate signal on demand with your own driver and feed it directly (with an interrupt of the existing signal so that you prevent interference). There must be a speedometer feed or wheel sensor that you could use for the top speed cutoff. A high school kid with a Raspberry Pi kit could probably whip up something.
 

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I think the better approach would be to generate an appropriate signal on demand with your own driver and feed it directly (with an interrupt of the existing signal so that you prevent interference). There must be a speedometer feed or wheel sensor that you could use for the top speed cutoff. A high school kid with a Raspberry Pi kit could probably whip up something.
Yeah that's definitely beyond me. Maybe if someone else did it and posted a tutorial * nudge wink *
 

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Step one to this development task is to map out exactly what signal the ECU sends to the magnet clutch. Easy enough to do IF YOU OWN AN AWD VAN (which I do not!). You tap off the connector in the rear and record the data while making runs under different conditions. What's the clutch receive? Increasing amplitude? Increased 'on pulse' duration? Under what conditions and for how long?

Then you create an artificial signal to match that you can apply on-demand.
 

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Step one to this development task is to map out exactly what signal the ECU sends to the magnet clutch. Easy enough to do IF YOU OWN AN AWD VAN (which I do not!). You tap off the connector in the rear and record the data while making runs under different conditions. What's the clutch receive? Increasing amplitude? Increased 'on pulse' duration? Under what conditions and for how long?

Then you create an artificial signal to match that you can apply on-demand.
Thanks for outlining how to do it. Unfortunately it still sounds a bit beyond me...
 
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