maverick1715

Hello Porsche family.

My name is Alex, I live in Las Vegas and I tow a 28' Airstream with my 2012 Cayenne Turbo. I'm writing the bellow in order to give real life experience with towing some serious miles, as well as possibly get some insights for the mechanical issues that have been developed.

I've done the following upgrades:
1. Hitch reinforcement at Can-Am RV in London Ontario
2. Brake Controller Prodigy P2
3. I use the Equalizer 1000 lbs weight distribution

My Cayenne is factory equipped with (related to towing):
1. PTV
2. Air suspension (PASM)
3. Towing package


Real Life experience:
Last summer I towed my 2019 Airstream 27FB for about 9,000 miles. My weight at the scales with the TV fully loaded (2 passengers, a German Shepherd, 2 camping chairs, a grill, a Honda generator and a Mountain Bike) was around 6700 lbs. This is about 5% over what the max weight of the Cayenne should be. The Airstream's weight with all our personal items (kitchen cookware, clothes, bathroom essentials etc) was close to 6500 lbs which is way less than the maximum towing capacity of the Cayenne. Tongue weight was close to 850lbs. We did tow all the way from Las Vegas, NV to Grande Prairie, AB with many detours in order to explore as much as we could. The trip includes lot off road as well with the Airstream on the back. The trip took about 4 months.

Towing Feeling:
It was great! First of, I had all the power I needed at all times. If I wanted to pass someone, all I had to do was push the gas and the car was literally catapulting us forward even with all this weight on the back. The stability was amazing. I never felt any swirl or lateral instability. Semis crossings, over passes - you name it, I never felt any kind of lateral motion. Super strong winds from any direction, never felt anything and the Cayenne as well as the Airstream were both planted on the ground without any issues. This is interesting since the main complain I hear from people towing is the lateral stability of the rig, which was not an issue at all.

Braking:
I set my brake controller at 3.3V with Boost On if I was on the interstate or Highway, and Off if I was in the city (I will explain why). With Boost on, the brake controller gives lots of braking power at the trailer. If I do over 45mph, I'd feel the trailer slowing the Cayenne and not the other way around which is what I wanted. In this way I feel safer and I also save the very expensive brakes of the Cayenne. I had to do an emergency braking from 60mph going downhill and that rig could stop without any issues. The braking was actually so strong that a couple of things that were not properly secured slammed the dashboard. Again, I call this emergency braking when I had to apply full pressure in order to avoid a collision. When I'd go downhill, all I had to do was to leave the Triptonic on the auto mode, and manually downshift (Triptonic knew it was towing and going downhill and it remained on the gear I did set it at without upshifting). The Cayenne could keep the downhill speed I wanted to without having to apply any braking applications in most cases. If I would have to apply the brakes, I'd be very gentle and the trailer brakes would do the job without the Cayenne's brake pads even touching the rotors (because of the Boost mode "on" on the brake controller). When I'd get in a town or in a city and I'd have many slow speed stops and goes, Id turn the boost "off". Otherwise, the trailer would be very strong on the brakes causing the trailer to skid and feeling in the cabin every uncomfortable. With the Boost off, this was not a case. Everything was coming to a smooth stop without any problems. I did played a lot with the Voltage of the brake controller, as well as the Boost On and Off, and after many many different settings, I found that the best and most suitable braking was with the settings mentioned above.

Towing Speed and MPG:
My sweet spot when towing is 60-63mph. Not because if I'd go faster feels unstable, but mainly because of MPG and feels more relaxing. All I do is set my cruise control between 60 and 63mph and I dont have to brake, accelerate. I may go for hours without really touch brakes or throttle doing this speed. I'm on the right lane, traffic including semi-trucks are passing me but I can care less. Mostly speed limit is 70mph, and doing 63mph when towing is a very good speed. If I'd go any faster I'd kill my mpg and all I would gain would probably arrive at my destination 45' sooner. In my book this is not worth it. The fun fact about this through is that on steep uphills (over 7% grade) I still wouldn't have to do any change to my speed and that's when I was passing traffic. My MPG WHEN TOWING is between 12 and 13mpg. My average for 9000 miles was close to 14mpg since we used the Cayenne to explore the area without towing when we had set camp to a location. One day I did towed doing 70mph. Stability, braking was the same as doing 62mph with one huge difference on my mpg which was around to 10.5.

Cayenne Temperatures:
On steep grade uphills (over 7%) water temperature could climb as much as 220F and oil 225F but it never went any closer to the red line. Anything under 7% grade all temps were at normal operating. A few times the grade was over 9% with speed limit 30mph and semis were not allowed. That time I turned the AC off to be on the safe side and temps again did not go any higher than the numbers mentioned above. Turning the AC off helps a lot especially with the water temperature.

Mechanical Issues:
I don't know if the issues I'm having are because of towing or because of the age of my Cayenne since I found other posts with similar Cayennes not towing having similar issues. As we speak my car is at my Le Mans idly Porsche mechanic (literally) and we will get to the bottom of it. Once we do, I will post an update. So let's cut to the chase with the issues.

a. If I raise the suspension to the highest level, there is loud clicking noise coming from the rear diff every time the wheel complete a full 360. This noise goes away on normal suspension setting height.
b. There is a grinding noise coming from the rear diff on slow (2-10mph) right or left turns (when there is load on the diff)
c. if I lock the center and/or the rear diff the grinding noise returns and it gets very very loud.
d. Sometimes when I start the engine I get "Rear Differential Fault" message.

Depends what the real findings are, I may fix it and sell it, or fix it and keep it. The Cayenne just crossed 92,000 miles. Next year my wife and I are having plans on towing close to 10,000 miles and I want to make sure the Cayenne is up for the task and as of now I'm not 100% convinced it is. If the Cayenne is not up to the task, I'm considering replacing it with a 2020 F-250 Diesel w Tremor Package. Yes I know, from "underkill" to overkill :-)

I welcome any feedback and I'm attaching all the repairs and work my Cayenne have had since I bought it brand new back in 2012 as well as some pictures from our trip. Any questions are welcomed and I will answer them at the best of my knowledge. Thanks for reading.

Alex

TV911

Great post! Very informative. I own a 2011 CTT, and had no doubt it could haul such a load with ease. I've only towed lighter stuff so far. One minor nit... the transmission is not a "Tiptronic", it's a PDK... a faster, smarter, upgraded automatic transmission.

What's up with the service visit on 1/14/15? Engine replaced?!! What happened?

Also, what was done on 5/31/19 to the transmission? That was expensive.

maverick1715

Hi! The transmission is Tiptronic in all Cayennes including the latest ones. Porsche only uses Tiptronic on Cayennes because of the higher towing ratings. For some reason PDK cannot haul big loads. PDK is found on Macans though (and 911s).

Engine developed a knocking noise around 20k miles. After my multiples insists to diagnose (dealership was insisting it was a normal engine sound), dealership was finally able to check cylinders with borescope and found 2 scored cylinders. Entire motor was replaced under warranty.

I did a transmission service before my summer trip on 5/31/19. Porsche recommends to do the transmission service at 160k miles. Because I tow a lot I decided to cut that in half :-)

s996

Excellent post thank you

I am considering the same with towing my 14 diesel. Our only concern is tongue weight and the air suspension. Does it sag during the night and have the air pump running a lot?

Rear Click may be cv joint or drive shaft with change in angle of ride height. I would definitely let the dealer that just charged you an arm and a leg for service check that one and fix it.

Good post

maverick1715

I have set my weight distribution in such a way that when the Airstream is hitched, the sag difference on the rear is about 1.5" (compared with the front). Once you turn the engine on, the air suspension levels everything out (rear end lifts up about 1.5"). Without the weight distribution the sag on the rear is a lot; not sure how many inches, but really a lot. The weight distribution transfers about a third of the tongue weight on the front axles and about a third on the Airstream's axles. The air suspension then makes the micro corrections and levels everything 100%. It does not sag during the night and I have never hear the air pump running at all. Once the Airstream is hitched, after the first engine start everything is completely leveled out.

Dealer and I are no longer together, I divorced them when they did my transmission service back in May (transmission fluid leaked after 400 miles into my trip, they botched the service and I ended up getting it fixed at the dealer in Bend, OR which was a great experience - super highly recommended). As of now my car is on the rack at my indy's shop figuring out the mentioned issues. I will relay to him your recommendation and thank you very much for it.

If you re enforce the hitch I wouldn't worry too much about the tongue weight as long as you use a weight distribution. Hitch reinforcement can be performed at any shop that can weld I guess. CanAm in Canada make it sound like it's rocket science, but in reality is a very simple "hack". A curved steel bar going from the receiver onto the chassis right under the car. With the Cayenne diesel I would expect around 17mpg towing a similar rig as mine at around 62mph. Great vehicle!

Jon D

I also own and tow a 27 Airstream International Serenity FB, started with 1/2 ton pickup, the issue with all these discussions is payload. My 1/2 ton had plenty of power and torque, never exceed total CGVW. Was over payload first trip on axles. Towing was ok but I knew the trailer was there and felt uncomfortable that long term was not a the best TV. Upgraded to an F350 cause got a better deal than on the equivalent F250 and they ride the same. Night and day difference towing. The combined rig is just stable, up mountains, down mountains, crosswinds etc. not saying you can’t do it with a Cayenne etc but also don’t believe it’s ideal.

maverick1715

Couldn't agree more. That’s the why I’m considering an upgrade to an F-250.

garrett376

Get the code read for the Fault Rear Differential. You may just need a new $3100 rear differential and you're back in action. They tend to wear out and make noise/vibration, or the servo motors fail, or the control units go out...

maverick1715

Already done that and so far seems servo motors have failed (reverse polarity error), you are absolutely right. We are currently investigating what else has failed. My dilemma is, did it happen because of the heavy towing? If I replace the diff with latest and newest version, will the new diff prematurely wear because I tow all this weight and I'm 5% over the maximum weight of the Cayenne? Nobody wants to replace rear diffs every 50k-90k miles.

garrett376

Nobody wants to replace them, but it seems to happen with these, whether it's the transfer case, or the PTV differentials. Due to your roughness when turning, it's likely need a new diff, not just a new servo motor. Servo motors are expensive at $800 or so, and come with a new differential.

the head

If you have the time I'd be interested in reading your thoughts on the airstream and why you picked a 28'.
The Fords are great tow rigs, I went with a cheaper Nissan Titan XD and while it doesn't have the towing weight specs on paper, it is definitely up for the task. It's also my daily driver. I went with gas over the diesel - that particular Cummins has issues.

maverick1715

Airstream - Love the floor plan and size is perfect for my wife, dog and I. I can fit pretty much anywhere without sacrifice interior space. In regards of the Cayenne I have my mechanic's update. The rear axle (left shaft to be exact) doesn't flex anymore, so when suspension is on high level it tends to drag and make clicking noise. This caused the servo-motor that locks the diff to skip teeth and brake which caused the grinding noise when taking slow turns. Also, we took apart the rear diff and we found out something very interesting. The 2 spider gears in the rear diff which actually are the ones who move and put down all the power have been worn out extensively. This is because of the heavy weight and these gears are made of cast. My mechanic is looking into 3D printing new spider gears that are made from a material stronger than cast in order to upgrade them. Cayenne is a great vehicle, it will be safe to handle the mass of the Airstream, but overtime it will wear items like gears that were not built to handle this heavy weight and are very very expensive to repair. If you tow only 2k miles/year that's not a problem, but we tow 7,000lbs about 10k miles/year and it can get expensive on the Cayenne.

cbracerx

Excellent post! I assume you are using the factory hitch. Would love to see a picture of how it was reinforced.

dapopa9

@maverick1715 Does the Lance Change Assist (LCA) on the mirrors still function while towing?

maverick1715

No, LCA auto disables when towing.