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Mizzmo

Towing Nerdiness

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I just finished a 1600mi round trip towing my F-27 behind a 4Runner V6. I thought I would share a new gadget that I used on the trip. I bought a Bluetooth enabled OBD reader and iPhone app that enabled me to track a whole bunch of vehicle system data. I settled on monitoring torque converter temp, transmission temp, engine horsepower, instant fuel economy GPS speed and altitude. I found that I was able to change my driving habits to considerably lower transmission temps and improve fuel economy.

I bought this OBD reader: https://www.amazon.com/gp/product/B00QJRYMFC/ref=od_aui_detailpages00?ie=UTF8&psc=1

 

I liked it because it was one of the few that worked with iPhones via Bluetooth. Most others go with WIFI which has higher power drain when the car is off.

 

I then bought this App: https://www.obdsoftware.net/software/obdfusion

 

There are a large number of Apps available, but I chose that one because it specifically it was compatible with my OBD reader.

You can pick from any of the SAE PID data streams, and you can read diagnostic codes and reset the check engine lights from this app. However torque converter and transmission temperature (which is what I was primarily interested in) are not standard PID values. The app allows you to make custom PID values, and after searching the Toyota forums I figured out how to do it relatively easily.

 

The update rate was about every .5s which was plenty good to see HP rising as I went up a hill and I pretty quickly figured when to allow the rig to slowdown to prevent downshifts on overpasses. I also learned that below 45mph the 4runner doesn't lock the torque converter resulting in higher temperatures. By accelerating at a relatively rapid pace I was actually able to keep temps lower until I got to speed and the TC locked. Operating temps at 60mph were between 165F and 180F which is not much higher than normal non-trailer temps.

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Good info. Thanks. Yes, keeping Trans temp cool is important. And you're correct about the lockup torque converter....when in 'slip' mode it runs the Trans oil temps way up.

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Good info. Thanks. Yes, keeping Trans temp cool is important. And you're correct about the lockup torque converter....when in 'slip' mode it runs the Trans oil temps way up.

+1 on trans temps. My dad blew up his transmission in 1997, towing a Bayfield 23 form Nfld. back to Montreal. he made it to withing 1.5 hours of home when the tranny went. It spewed oil allover the bottom of the Truck (Chevy Blazer) which promptly caught fire. Had it not been for a trucker with a real fire extinguisher, he would have lost both the truck and the boat.

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Just had a failed torque converter take out my tranny . Heat is the #1 killer of trannys. Might look into this.

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Yeah, this all started because I was getting a transmission shudder. I flushed the "lifetime" fluid and it is gone, but I wanted to know what I was doing to my transmission while towing.

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Mizzmo - under the heading of "stuff I'm too lazy to do myself" - any chance you could post (or PM) the details of how to dig out the non-SAE data?

I've got a Yota myself and wouldn't mind access some of that info.

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Yeah, this all started because I was getting a transmission shudder. I flushed the "lifetime" fluid and it is gone, but I wanted to know what I was doing to my transmission while towing.

Does your model's instructions tell you to tow with the shifter in 4th (if a 5- speed auto) or 3rd (if a 4-speed auto)? My '09 RAV-4 with a V6 and 5-speed, the same drivetrain as a Sienna or Highlander, is supposed to be kept in 4th so that it doesn't "hunt" for where it wants to be all of the time. Using that setting also cuts out the TCL that would normally occur between 4th and 5th.

 

So, I'm just curious where the tranny was while tracking this data. Pretty interesting use of the OBD...

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Mizzmo - under the heading of "stuff I'm too lazy to do myself" - any chance you could post (or PM) the details of how to dig out the non-SAE data?

I've got a Yota myself and wouldn't mind access some of that info.

https://www.tacomaworld.com › ... › 2nd Gen. Tacomas (2005-20

 

here you go. The equations change slightly with each model group, but this thread covers many of them.

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atoyot- Yes it says to keep the car in 4th, which I did. I did briefly experiment with leaving it in 5th, the problem is not hunting so much as the torque converter. It seemed to stay unlocked a lot which caused temperatures to get really high really fast.

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My bet would be that the clutch pack/discs were slipping in 5th/OD, and the TCL doing the same (when not shifting in and out). A transmission guy who swapped out a 700R4 GM tranny for me, some years ago, explained that as the reason not to tow in "O" in my, at the time, police interceptor Caprice. It was basically a Chevy Suburban drive train, front to back.

 

He basically said that the most heat happens during / because of shifting, when friction happens. That, and slippage under a load from towing in the wrong gear. Torque converter lock-up was explained as basically an add-on to get CAFE mileage up just a little bit, on the backs of the car owner who has to pay for repairs due to the TCL's inability to take much more than wind drag on the car or truck. Now, I'm sure that is a VERY simplistic explanation, or theory, though the net result is the same any way it's worded. Again, I appreciate the feedback on the OBD tests.

 

My last car, a Honda CR-V, had to tow in third gear for this reason; 4th and 5th gears were both overdrive gears and each gear had a motorcycle-style clutch pack of its own. Had there been a way to just cut out the TCL, it might have been fine in any gear, but not worth the chance of tearing it up just to get the boat 80 miles to the bay and back. I did add a transmission oil cooler to that vehicle, just because.

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After selling our boat in Annapolis we towed a 2200 lb trailer of our possessions from there to Vancouver BC. With a Mazda 626, 2L 130 HP, 4 cylinder engine, 5 speed manual transmission. Usually kept it in 4th. Engine lugged in 5th. But we kept up a steady 70 mph on flat highways.

 

Tow ratings seem to be very conservative. The 626 was not rated to tow ANYTHING in North America. But apparently it was OK to tow 1000 lbs in Australia so I believed that. Didn't know the trailer was 2200 lbs until I used a self service scale in Alberta!

 

I would have loved to know how much I was abusing the car...

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Maybe not for everybody - but get a diesel and trailer at max 85% of vehicle load rating with proper tongue load and you will be fine. Changed my SUV from V6 to diesel V6 and it's like night and day (plus 25% +/- fuel economy). Importantly the range increases to the point where you can put on miles without too many pit stops.

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Anybody with similar information about a new 2017 outback 6 cyl.  I am concerned about how the CVT will hold up if I tow anything bigger than a F24 (aka 2k lbs.)  Dont know if I could to an F27 or 28cc.

THoughts?  Or do I just suck up to a friend with a real SUV or pickup?

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Listed capacity is 2700lbs. Light displacement for an F-24 is 1800lbs. Usually that is without sails, motor, fuel, anchor etc, and certainly does not include the trailer. So in reality you are probably very close to the limit so  If you want to use it for short hauls it would probably be ok. I had a friend with a Forester that hauled a similar weight boat up and down the ramp, it seemed to do fine. He wouldn't move the boat more than a block though.

I am surprised to see that the CVT is rated to 2700 lbs, all the others I have seen were rated for 1000lbs or simply had a don't tow rating. I always suspected that was because the manufacturer didn't want to do  the testing.

My F-27 weighs 4000lbs inc trailer, and it is pretty stripped out so that would be right out. OTH you can rent a truck from home depot for something like $30 a day.

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On 2/20/2017 at 7:05 PM, Mizzmo said:

What vehicle do you have the diesel v6 in?

Gotta be a jeep GC. They made them (still make?) in diesel trim a few years back.

 

 

Another option here is to buy a K2500 Suburban with a 6.5 detroit. Just put 4k on mine in two weeks towing a star, 17mpg vs the 9 we used to get with the E-150..  and she was the best handling, easiest towing "rig" I've ever driven. Years better than E-150,4runner, etc etc. Big ole' front seat means you can drive in any position you want, especially with the bench. Big ole' storage area means you'll never run out of space to dirty up.

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Yeah, tow ratings in North America are ridiculously conservative. I think it has to do with people used to having big trucks as a reference and not willing/understanding that you have to drive differently if you have a heavy (relative to the tow vehicle) trailer...

Europeans tow all sort of camp trailers with regular small cars every summer and they don't seem to run into too much trouble as long as the drivers know what they are doing!

I towed my F-24 for a couple years with a Jetta TDI 5 speed. I had to limit the tongue weight to less than optimal which made it a bit squirelly above 90 (km/h) so I cruised at 80 and it was fine. Not suitable if you are going very far/very often but but was perfectly adequate for going the different ramps of the area within 20km.

Getting up the ramp was another story however... The gearing was such that I just could not build enough speed to engage the clutch all the way and had to slip all the way up the ramp (that wasn't going to last very long...) I now tow with a Mitsubishi Delica (5 speed) that has even less power than the Jetta but is geared such that it can basically idle its way up the ramp. Still can't cruise faster than 90 because I don't have the wheelbase for stability (also it can't!) but it handles the weight fine otherwise.

The point I wanted to make was that I did stop by a truck scale once and found that the boat and trailer, in "week end cruise" mode, i.e. with stuff such as cushions, porta poty and everything you need to go sailing (minus foul weather gear/clothing and food, which was all in the car) was 1550kg (#3400). That was quite a bit heavier than I had anticipated.

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Tow ratings in the U.S are conservative for two reasons: speed and tongue weight. In the U.S, 10-15% tongue weight is recommended and probably the law, which is stable to 100 mph or beyond. In England, for example, tongue weights are set to 4-7% and max speed while towing is 60 mph. Total gross vehicle weight of the tow vehicle is the limiting factor for tongue weights, which in turn drives the max trailer weight. The details are here: http://oppositelock.kinja.com/tow-me-down-1609112611

I think a diesel makes a lot of sense for tow vehicles, but who the heck makes them in the U.S besides Volvo? I see Buick is bringing the Opel Wagon to the U.S, but of course pairing it with a V6 instead of the diesel option I drove in Europe last winter (which I fell in love with, fantastic fuel economy, plenty of power, would have made a wonderful regatta vehicle).

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