RhinoComp

I think these both answer my question pretty well. So I'm still going forward with trying to get the dealer fix applied this week. I'm actually going to try to do a fluid change in my TC now as I just learned my 2015 is probably not covered any longer even though a 2014 with the same TC would be still... So I'm hoping both a fluid change and the flash resolve the little bit of clunkiness I've had in 2nd and 3rd gear occasionally. I would imagine it's likely still the TC being the root cause there, but the clunkiness also only really is noticeable after longer drives just like the power loss issue... So who knows. But considering I learned 2015-18 is only covered for 7 years on the TC while 2011-14 is covered for 10 years I'm suddenly a little less inclined to just throw a new TC at the problem...

Snipe656

My transfer case, like most, was replaced under the original warranty then that one eventually exhibited some clunkiness but the warranty extension was already out when that happened. Fluid change seems to resolve things for the past 10k or so miles. Figure eventually I am going to end up paying to throw another one in there.

RhinoComp

So I wanted to provide another update from myself personally, since I've had this software fix done. I made a long road trip out to Montana again and noticed after several hours that it seemed the highway cruise control boost issues still existed, albeit at a lesser amount. When we got closer to the destination for the first day, I had to do a lot of passing on a two lane highway entering Helena, MT. This meant quite a few passes over 100mph (allegedly). After these several passes, the "issue" seemed to be resolved and I could even hold boost going up 9% grade mountain passes without dropping any speed at all with cruise control for the remainder of the trip and even through the drive to Bozeman the following day.

The issue before and after the software fix is different, let me make that clear to start with. Before the fix, the car would build about 3-4psi and then abruptly cut back to 0 unless I very lightly edged onto the throttle. And during these conditions, I could not build boost even with my foot to the floor. It would take downshifting to 4th or 5th just to make any power at all, and even then I wouldn't top 7-8psi. Post-fix, there's no more abrupt boost cuts on the highway. But when the "issue" is still present, the car is still building to 3-4psi and maintaining some speed, just not always enough. Interestingly, the car will actually downshift into 7th to help it regain speed again which it wouldn't do before. So it'll downshift if it gets about 4mph below cruise set speed, whereas before I could drop almost 10mph without the car making any boost, downshifting, anything like that. So this fix has absolutely done something to help, and even with the issue still remaining a little bit, the difference in drivability when present is miles different. For that reason, I still 1000% recommend that any new owner make sure that this software update is performed. Especially since It also means my car now gets the EPA rated fuel economy whereas before the flash I couldn't even get within 2-3mpg of it even with hypermiling techniques.

This brings me to my internal thoughts I've had since this trip that I just feel I need to share with the hive mind. It all makes me wonder if these issues on the highway after longer periods of time may not solely be due to the knock sensor issue, but potentially the ECU's driving style learning/adaptations. I can't remember where I read about it on the forums, but I recall shortly after I bought my Cayenne S I read somewhere that the ECU performs driving style learning and adaptations to "optimize" your driving experience with throttle sensitivity, shift points, stuff like that. I don't know if or what extend the ECU truly does all of this, but it could actually explain a scenario where the vehicle adapts to only being driven incredibly softly on the highway with minimal boost for several hours, and it adjusts parameters because it believes that this is how it's desired that it drives now. My hypothesis is that most of these parameters that could be adjusted may deal with throttle mapping more than anything, and in that case the ECU may regress the throttle input mapping i.e. 30% input means 15% throttle, 60% input means 30% throttle, 100% input still means 100% throttle, so a progressive mapping instead of linear or digressive mapping. On some vehicles I've owned, I've noticed some cruise controls aren't afraid of giving 100% accelerator input to regain or maintain speed, my previous Ram Hemi and few BMWs were like that. I don't think the Cayenne wants to give an overly high amount of accelerator input from cruise control, and that could potentially explain why it doesn't like to give more than 3-4psi when trying to go up a steep grade during the "power loss" condition. But after some romping on it for a bit to the point where I can feel the throttle map sharpen up a bit, I can manage 9-10psi in 8th gear going up the same steep grades, even with cruise control doing the work. So essentially if the cruise control hypothetically doesn't want to go above 40% input at any time, that could mean the ECU doesn't give more than 20% throttle in this hypothetical driving parameter adjustment and maybe that's just not enough to build the appropriate boost to maintain speed on steeper grades, but when the input is more linear per se, the cruise control could give a higher throttle %.

Now again, I don't know by any means if this is how the Cayenne's ECU works, but I just feel the need to get my thoughts out and my own hypothesis to potentially be read by a greater mind than my own. Perhaps someone with a lot more knowledge on these vehicles, especially anyone with tuning experience, could chime in with their thoughts regarding this. If there's tables in the engine tune that allow for the computer to select a range of throttle maps or other parameters, I would think this could be something that's addressable with a tune. Ideally, I would love to be able to datalog to compare the differences in how the vehicles behaves with the issue present versus not present. I think it would be very telling to look at the difference in requested throttle versus position, boost targets versus actual, timing advance, knock retard, all sorts of those things. I also just know it's incredibly tough to diagnose and log an issue that only seems to become prevalent if you've driven on the highway on cruise control for 4+ hours.

Okay, mind vomit over!

Hayabusa3

Hi guys - second post on Rennlist.
I picked up a 2015 Cayenne S and about 10 days into owning the car I developed the symptoms, same as described above. First developed on the freeway after about 20 miles of normal driving, I noticed the car felt pretty gutless like I was dragging my brakes or towing a very heavy trailer - I knew something was very wrong but had no idea what was happening, I thought the worst! My cluster wasn't set up to show boost on the display so I didn't know that I didn't have boost. Pulling off the freeway and cycling the key didn't bring the boost back for me so I jumped on Rennlist and saw this thread.

On the same road trip I pulled off later to get a drink and try to calm down - not let the thoughts of a new expensive purchase turning into an even more expensive purchase wreck my head. When I started driving off again I felt the boost was back and knew there wasn't a mechanical failure and figured the software patch would work. This car has 145,000 miles and is in perfect condition so I couldn't fathom how the previous owner hadn't had this addressed. Surely this problem didn't just start with my ownership at those miles? My Software version was W09C0068SUBFA and the bulletin above changes it to W09C10BD68SUBFN.

I took the car to the local Porsche dealer and spoke with a friend of a friend (I worked as a certified Audi technician for 20 years) and had them recode the computer - problem fixed.
I set the cluster up to show boost so that's sorted out too.

The dealer did suggest that from time to time, because of coolant leak issues, sometimes the knock sensors can get damaged by coolant causing similar complaints.

Thank you to everyone that reposts their finding on this form so that others can benefit.

PFDGSB

Nice when it's such an easy fix, right?

Hayabusa3

More like "Awesome"
it's so frustrating to search through forums to see others with your same issues but no follow up reply or resolution. Thank you to the Rennlist community!

ledbette

@RhinoComp What's your experience in Sport mode? Seems to me the car is a lot more responsive, but I really dislike the overly aggressive downshifts.

I've seriously been considering a Softronic tune, but would really like to drive a car with the tune to see if it corrects the sluggishness before dropping the $$.

juld0zer

Hi folks, this is my first post here and I own a 2015 Macan S which I believe has an engine from the same family as the Cayenne.
My background is in BMWs.
I have been battling the same issue/s shortly after I bought it, tried heaps of things to permanently resolve it and did my best to refrain from firing the parts cannon as there has never been any fault codes or any pattern that would suggest a definitive failure of a part (and I have realised that this DME takes a lot to make it light up the CEL).
The main difference is I hardly use the cruise control and I can reproduce it almost daily on my commute. I'm happy to share all my tests and logs later as it might be too much to unload in my first post. I have a Scangauge II for day to day OBD monitoring, and use a proper scantool for everything else including datalogging (with limited access to previous logs).
I rarely use sport mode or AC, and don't use idle stop start so for the purpose of minimising variables, I try my hardest to maintain these in all my driving. I always use 98 fuel (that's the best we get here)

The dash boost gauge is fed from the pre-throttle TMAP sensor. There is an identical sensor on the left side of the intake manifold. For testing purposes, the two can be swapped. The boost reading you get from an OBD reader will be from the intake manifold sensor. Disregard any literature that tells you they are different sensors because they allege the pre-throttle sensor is different because it is not designed to read vacuum. The part numbers are the same.

I believe there is truth to the oversensitivity of the knock control system. When I first noticed it, it was a very warm day in Sydney (28*c+), and I was almost flooring the gas pedal with no increase in acceleration. Ignition timing was down to 17* advance and fell with more accelerator input. When it isn't acting up, it's normally around mid 20s to 30s under the same conditions. Exhaust note was rumbling and groaning (a labouring sound). The Macan uses a PDK but like you guys have reported, it loses speed on a steady hill even without cruise control, refuses to downshift and by the time the engine is labouring stuck in that gear, you push the gas pedal more and then it kicks down 2 gears and eventually takes off. Since I have the Scangauge, I could see that the throttle was also being commanded to close (not fully close to idle opening angle, but it was close to idle) when this was happening. This was either a knock control strategy or PSM trying to cut torque due to wheel slip/loss of control.
One of the parameters available to see on an eOBD2 scantool is the "Ignition map RON dependent". This sounds like the octane scalar controls used on Ford EcoBoosts and BMW engines. Earlier BMW DMEs could estimate the fuel grade. I have never figured out what a good and bad reading is but I have seen this figure at 0 and 0.01494.

Although most of you have reported success with the software patch addressing the knock control system, I would like to point out that the TMAP sensors are now onto their 2nd or 3rd revision now. It seems odd that parts suppliers would revise a part and release a new part number unless there was an issue with the previous generation (why waste R&D expense) but it seems like a common thing in the VAG world. BMW does the same thing but nowhere near as often. My car came with 2015 made sensors, but 2014 ones are also in circulation. This Bosch part number was 0 261 232 012.
The latest revision (Bosch part number 0 261 232 022 (Porsche 06E906051AA, VW/Audi 06E 906 051 AB) has a graphite coated oring whereas the previous ones had a green oring. The same series of sensors is used on some Audis, the most common application here would probably be in the 8V series RS3. In my research, there has been some suggestion of iffy TMAP sensors causing boost issues on RS3s but there isn't a lot of detail. The reason I bring this up is because I noticed some unusual behaviour with the old sensors: after the engine is shut off (leaving the vehicle or idle stop start), sometimes the manifold reading would show a small amount of boost which is impossible transitioning from an idle state. Recently, I noticed the manifold pressure on the Scangauge read higher than the boost gauge on the dash (ie. manifold pressure higher than pre-throttle pressure). Again, an implausible scenario as the throttle flap is used as a boost control device on these engines so theoretically, the boost should always be higher before the throttle body. This is a difficult one to capture on the datalogger as it seems to happen too fast for it, but the impact on performance is obvious - the DME can see the manifold pressure is either above the setpoint or in an implausible situation so I believe it is commanding a boost cut via the throttle flap. The throttle position closes to near idle angle and the vehicle accelerates poorly to maintain cruising speed 50-60kmh+ or in an overtaking scenario. Pushing the gas pedal more doesn't produce a linear effect on the throttle angle as it seems pegged in that limiting angle.
Another situation I noticed was ascending a multi-storey car park. Normally the PDK holds 1st gear on the ramps but due to the DME "seeing" more boost inside the manifold, it made the PDK upshift to 2nd about 3/4 of the way up the ramp. Totally inappropriate at 10-15kmh on an incline.

These are not analogue sensors as they output via the SENT protocol so you can't really spoof the signal for any testing purposes. I mentioned the 2014 made sensor earlier because I bought one brand new sensor from a dealer in 2023 to try and fix the boost issue and that is what they sold me. I installed this sensor in the pre-throttle position but there was no change in boost consistency. I recently swapped it to the manifold position, which is when I noticed all those issues in the above paragraph. I can only assume that in the pre-throttle position, it was also reading higher than actual boost pressure and thus was escaping scrutiny because the symptoms were not as obvious. What may have also been happening was the sharper pre-throttle pressure sensor curve may have skewed the wastegate control logic to try and regulate the boost curve which just added to the doughy feeling under acceleration. By the way, you can drive with the wastegate solenoid disconnected pneumatically or electronically. It won't actually throw a CEL.
I recently bought a pair of the latest revision sensors and it drives a lot better and more consistently in terms of predictable boost. The manifold sensor has a huge influence on the behaviour of the engine and transmission, even the brakes as it seems to use manifold pressure (or vacuum) as an indicator of driving condition (braking, coasting, cruising, engine braking). If anyone continues to have boost issues, I would suggest trying a new pair of TMAP sensors. I got mine from Rockauto as they are currently the cheapest.

The second issue I wanted to touch on was the false knock issue. On many other cars, a vibrating exhaust can cause false knock (Mustang, LS engines etc). It was a common issue on the midpipes of the Macan S, GTS and Turbo to vibrate heavily when coasting due to the mesh supported flex couplers sagging, allowing the whole exhaust system to effectively vibrate up and down. I replaced these with the updated versions which has woven flex sections instead. Unfortunately, the old pipes had broken the reinforcement brackets that joined the pair of pipes before the rear diff so the impact of resonance is real. I had an exhaust shop weld in a new bracket to re-join the two pipes. I would suggest checking your exhaust system for an vibration. Pounding it along its length with your fist and listening for resonating noises is sufficient.
You guys also have a torque strut joining the right hand rocker cover to the body. As my car has over 120k km, the rubber bush on the engine side had turned rock hard and caused a knocking noise over corrugated roads. The noise was akin to a suspension/chassis/ball joint knock. I am not sure what the Cayenne ones are like but they live in a hot part of the engine bay so perishing would be likely. During my previous testing, I removed the torque strut when I was trying to pinpoint the knocking noise and the engine and transmission became extremely smooth and responsive. On the Macan, it is attached using aluminium fasteners. I replaced the torque strut a year ago with an OEM part from FCP (looks like the genuine part with the logos ground off), but it sounds like the knocking noise is starting to happen again and the ignition timing it starting to drop a bit. I replaced the body side fasteners with high tensile steel fasteners and a large washer and tightened it as much as I could using a 2ft spanner. So far so good.

If anyone is about to embark on a drive that is known to bring up the no boost issue and hasn't had the software patch done, may I suggest removing the torque strut? I drove without it for a week. I loaded up the drivetrain by accelerating against the brake with the hood up and the engine didn't try to leap out of the engine bay but obviously use your own judgement as this can finish off any engine mounts that are already marginal.

Hayabusa3

Lots to digest there - but the software fixed mine a few months back and it's been flawless since. So the knock sensors on my car are performing perfectly.

carenthu

How to approach dealer for this fix?I do my own DIY and my car is not under warranty or CPO.

Graufuchs

I had the same dilemma, I printed out the TSB in this thread and brought it to the dealer. I handed them the TSB, told them I only wanted the revised software, it cost me $150.

I was in and out of the dealer with an appointment in about an hour.

The update corrected the boost pressure loss and hesitation.

ledbette

Same here. Same cost.

carenthu

the car drives so well and the sports mode works like sports mode too. I am not sure how the previous owner drove for 85k miles without this.. I just went with the TSB update and paid for it and best thing I have done to 2015 porsche cayenne s. Now the car is really using the turbos and shifts better for normal and sports mode. It holds the gear and develops the boot pressure.