Hi
I have a 2009 Cayenne GTS living in California, and driving at high altitudes like Lake Tahoe and Mammoth Mountains, with high outside temps, I experience engine droop, defined as sudden engine RPM degradation, while holding my foot steady on the accelerator peddle. Engine power just falls away momentarily, and then with the accelerator peddle depressed, the engine RPMs accelerate with a thump to the vehicle. The vehicle throws no codes, and when cooled, operates normally. NO ISSUES

It felt like the vehicle had low transmission fluid level, and I attempted to make a refill. I leaned this vehicle has a sealed transmission system, and could not be topped off. High temps and high altitudes seem to cause a problem with engine performance, kind of like a hiccup or a stomach belch.

Does any of this sound familiar?

Thanks for any ideas,
Brad

 

The transmission doesn't use a traditional dip stick. You should check your transmission fluid. You should also change it if you haven't already.

http://www.pelicanparts.com/techarti...ter_Change.htm

 

Not exactly correct - the transmission does not have a dipstick, but it also is not a sealed unit. You can remove a large hex bolt on the bottom of the transmission pan to fill the unit. However, filling it to the right level is temperature sensitive and a pain in the rear.

Why not ask a local Porsche service manager? If the dealer is in a high altitude area, they will have the best perspective on what is and is not normal for your make/model.

 

Those symptoms sound the same as what happened to my 09 CTTS. The transmission was also the first thing I suspected, though the problem was intermittent and not readily reproducible since I wasn't initially aware that high ambient temperature would exacerbate the condition. So for unrelated reasons, I had the transmission fluid changed, which did nothing to prevent the car from finally going into limp mode leaving Las Vegas on a hot summer day (110+ F) a few months ago. Only then did it finally throw a high pressure fuel pump (HPFP) code.

Changed the HPFP (this was at 91k miles) and everything has been fine since, though admittedly I have not tried stress testing it in very hot weather. The confounding issues that makes it not obviously a HPFP issue, in my opinion, is that at normal ambient temps, there is zero loss of power at all. WOT anywhere in the rev range would be perfectly normal. The stuttering, when it starts, makes it feel like a transmission problem as it kind of feels like a disengagement, but turns out it was because the engine was "coasting" and fuel starved.

So hope this story might help, though it's hard to reproduce and doesn't readily throw codes, so good luck with the diagnosis!

 

I had the opposite problem when my engine got WARMED up...Transmission occasionally wouldn't UPSHIFT. I had two fault codes, but in the end, replacing the Crankshaft Position Sensor (the first fault code) solved the problem.


Included the URL for that thread, another forum member (EMC2) posted some useful how-to tips there for the CPS change.


https://www.6speedonline.com/forums/...4-problem.html


good luck with the fix!

 

Brad,

Did you ever resolve this issue?

I have the same car with the same issue.

Justin

 

My Panamera in hot weather would go into limp mode after about 5+ minutes after running it. Through transmission fault, PSM fault, check engine, repalced the coils and runs great again even in 97F air temps. Was intermittent at first, and would run good some of the time, then after 10 more outings almost stranded me. New coils, had changed the spark plugs 15K ago, looked at then and kept the same. MPG back up to 27+ mixed driving, so I'm happy.

 

My issue is likely related to Density Altitude or oxygen levels. As the higher the altitude the lower the outside temp needs to be for the event to occur. For example, at 105 degrees F the RPM droop will occur at around 3000' elevation but at 7000' elevation the event will occur when outside temp is in the low 90's. Maybe the computer is leaning out the mixture too much.