cdog533

OK...I took some videos of the boost not working --- then working fine 2 minutes later. The boost gauge is in the upper line on the right:

HERE IS THE BOOST NOT WORKING:
I was at WOT, had the shifter set to manual mode. First in 8th, then 7th.



TWO MINUTES LATER, HERE IS THE BOOST WORKING FINE:
Again, at WOT (in some traffic though), and in manual mode. First in 8th, then 7th. To me, this is the car behaving normally and as intended. Boost going up with rpms as is typical.

I have no idea what triggered the change between the two videos. I didn't stop the car or do anything except drive it for a few miles at about 75 mph.

Also, I got the same results in any mode (normal, sport, sport plus) - no boost initially, then boost working normally the rest of the trip - I tried changing them up; it's not dependent on the setting.

It appears that there is some trigger/condition in the software that prevents full boost. Then whatever that was was no longer present, so full boost was OK. I had been driving the car 20 minutes in total, but had stopped for gas about 5 minutes prior to the initial 'no-boost' test. The 'OK boost' test was about 2 minutes later. Maybe it has some lockout until some amount of running time following a stop?

I wonder how this would be affected by GIAC or Cobb software tunes (once available).

Snipe656

Since I never used triptronic back when mine was plagued with the issue I could just not say with certainty if that displays the same issue or not. Mine definitely today does not do what your first video shows. I do know if your vehicle is experience the exact same issue it would not take just trying in 8th gear to expose it when it is happening. But also can say mine would have it one minute and a few minutes not at all on some days and then other days the entire day and then on some days never.

Outside temps seemed to play an issue but I did not get to drive in colder weather too much since bought the car in late April and dealt with issue from late May until August then live in the South. But during all that I was in Lubbock one weekend when a cold front blew it at night, the vehicle ran perfectly in that cold air for that night but all day prior and after it was a slug and air was much warmer.

Here is one I took when driving to the dealership to show them the issue at the time. My throttle position never changes in it and notice right at the beginning when I started the video it jumps up 0.4 then immediately 0s out, also notice that I gave it enough throttle to cause it to downshift from 8th to 6th. Acceleration makes it look like I am not giving it much throttle yet I am. This was taken on flat open road so no inclines to try to battle.

wkearney99

Not sure if this is related or not.

Snipe656

I do not think so since you state you mash the pedal then a 1.5 second later power really delivers. Guess it would depend on ones definition of mashing the pedal, I just assume you mean flooring it and if so when this "loss of power" issue was happening on my car the vehicle never could back out the boost if I floored it though it did have to ramp up the power. I suppose that ramping up of power maybe would meet your description but it really seems like something else is happening on yours.

The easiest way to tell if this "loss of power" issue is happening for you would be to have the boost gauge displaying on your dash and watch it. The backing out and keeping out boost always happens after a little blip of boost displayed on the gauge then it keeps boost zero'd out unless you basically floor the gas pedal. When things are running correctly it is going to make boost with very little throttle and going to keep(if not build depending on throttle position) that boost so long as still giving it throttle.

Here is an example of it from a dead stop, at least 1/4 or more throttle throughout this video, probably closer to 1/2 throttle. Notice right at the beginning is a blip of boost then nothing for the rest of the video even though maintaining much more than grandma level throttle position. It does not seem like this sort of situation is what you are describing.

wkearney99

I have a Bluetooth ODB dongle and the Torque Pro android app. With it I can see, and log, a number of engine sensors. I find Torque does a much better job of showing real-time changes. The MFD barely shows any change to the Boost level, it seems to lag quite a bit. Torque, however, shows it about as close to real time as you're going to get ECU->OBD->Bluetooth->Phone->app.

I'd wonder if your situation might be more clearly observable via OBD data monitoring instead of relying on just the MFD?

Snipe656

My issue was resolved back in August but perhaps had I had something along those lines it would made it easier for me to show dealerships the issue. At the time I really had wished I had a way to measure and record throttle position.

But the boost gauge when these vehicles are working correctly is very quick to show the boost. I have to really try to make no boost show up on my gauge when I am accelerating. So I really do not follow the statement about the MFD barely showing any change in boost level unless you are referring to my video and that video was taken to show that exact problem.

Here is a video I took after things were fixed. It has some annoying music playing on the radio, due to an inside joke with a friend I was originally sending it to. The throttle position in this video is just like the one in the video up above that I posted. Notice not only is it making boost throughout the video but the vehicle is moving a lot quicker for some short recording:

wkearney99

Hmm, that's much faster graph responses than I see.

Nevermind, engine replacement. Yikes. I'll have to dig into this further. I'd very much like to avoid time wasted dealing with repairs.

cdog533

Guys, I had my Cayenne at the dealer today because of a transfer case issue (case being replaced at 18,000 miles, sigh) and showed the boost situation to the tech who was riding with me witnessing the horrible transfer case clunk.

Luckily, today was one of the days when I could hold it at WOT and it was making ZERO boost at like 70 mph in 7th and 8th gear. He recognized there was an issue and that this was unusual, but he wasn't sure what could be causing it. He was going to check all the turbo plumbing and check for any fault codes.

cdog533

So, they replaced the transfer case. Car now drives normal and is actually smoother than new, making me wonder if transfer case has been wonky all along. NO fault codes ever by the way.

The tech agreed that the 'NO-BOOST' issue was odd. And the fact that it was intermittent was odd. They could find nothing wrong with the car (no turbo lines off, no codes, etc.) and said the car is operating normally according to the analyzer (PIWIS II).

Given that, I'm thinking this issue is caused by something in the software limiting boost under some set of parameters. This is likely affecting every turbo V-6 Cayenne and maybe Macans too.

wkearney99

THIS. I'm wondering if there's possibly something relating to the traction control that's coming into play here. As in, it's thinking there's a traction-oriented issue here and decides against allowing boost. Which might explain my left turn situation, but wouldn't explain what others are seeing straight line. Well, not unless a slipping transfer case causes something that the system thinks about in the same manner.

I'd think some kind of logging would help clarify the situation. But I don't know what (if any) software would be capable of logging enough of the sensor data to be useful.

Snipe656

Mine too got to the point with pedal down no boost. The problem just progressively got worse and more often with the more miles I put on the vehicle.

If you are having the problem you really should work on escalating it so it gets to someone above the dealership level. As I mentioned before(maybe in this thread), it was explained to me in detail what is causing the boost to be removed and at that time(last August) no fix existed outside replacing the engine since the root cause of the problem is a sound being produced inside some engines.

softright

So did transfer case replacement resolve the power loss / boost issues in the Cayenne S? I have same loss of power, very short boost duration when accelerating at high speeds, loss of speed in cruise control. 2015 Cayenne S. No noticeable sound coming from transfer case, but wondering if software is cutting boost / power because it thinks drivetrain is slipping?

Snipe656

That is basically the description of the symptoms mine(also a 2015 S) had if only looking at it from a freeway driving stand point. Can read back through the thread and see what Porsche's solution and stated reason for the issue was for mine. Since you have the same basic symptoms and since they(not dealership, but the region tech) told me it is happening on other vehicles, probably good chance same problem.

I had two different owners tell me they were told a software fix would be out last month for this. Not heard from either on if that story came true or not. I am going to be at the dealership later this week and plan to bug them about this, not that my new engine has had any issues but sure suck if post warranty it does.

cdog533

I haven't seen it doing the 'no-boost' thing since the transfer case replacement, and I've tried to replicate it maybe 5-10 times. NOTE: That doesn't mean it's fixed for good though, as the boost issue was always intermittent.

softright

Thanks for the reply guys. Right I neglected to mention that my issue is intermittent as well, but seems to only be evident / noticeable cruising at highway speeds. Almost like a limp mode without throwing codes. Or a traction control issue without flashing dash lights. I scheduled appointment but it is 2 weeks out. Will show this thread to tech. Interesting that the first word out of service writer was transfer case. Could just be coincidence since the TC failures seem to be fairly common.