CarGuyNVA

I've been following this thread for a while now with passing interest. So I'm curious, if the above information is correct and the cause for the internal 'sound' causing the knock sensors to trip up is unknown by the engineers, what assurances do you have that your replacement engine will not begin doing the same at some point? I mean if they don't know the cause yet, the new replacement engine logically would have no changes/enhancements in place making it any different from your original engine, correct? It seems the vehicles start out performing fine for a considerable period of time, and then start acting up. I'd just be concerned that you might start going through this all over again. Unless they really know more than they're saying?

cdog533

Update: I still haven't had the 'ZERO BOOST' issue occur since my transfer case was replaced 30 days ago.

I'm not sure if the transfer case was giving bad data to the system and that was resulting in the zero boost situation... OR

If there was some software update that was done along with the transfer case replacement that has resolved the problem.

But for some reason, it has boost (as normal) in higher gears and hasn't yet gone flat with zero boost like it used to do. You can see my videos earlier in the post for an example of the zero boost problem.

deilenberger

That's pretty interesting. If the clutch was intermittently slipping, it would cause torque surges up through the entire driveline, including the engine - and I can imagine the ECU cutting power to limit the slipping.

Please DO provide details of your torque-converter replacement so you can be added to the ever growing table of victims located:
https://rennlist.com/forums/cayenne-...sfer-case.html

I'd suggest adding the details in that thread, that way I'll spot them and add them to the database I'm keeping.

stronbl

Probably unrelated as this issue seems to be an electronic boost control rather than a physical / mechanical part failure. But on my '13 CD, I lost all boost last winter driving from TX to CA (as an aside the v6 diesel w/out boost is not a safe vehicle on the hills). My problem which also was an intermittent issue but later became non-intermittent, was a cracked boost hose. The crack was "sealed" in cool mornings or temps, at least until the engine temp heated up enough and then the hose opened up. Flat to a very minor grade was fine as there was enough torque and hp to maintain speed, but any grade (even an exit ramp grade) would trigger the boost failure - i.e. boost under load. For me there was an error code when the boost was lost -- reduced engine performance, loss of boost -- yellow colored CEL -- contact service center.

Once the boost pressure hose was replaced, all was and is fine. As I said at the start, probably not the issue here, but may be worthwhile having service folks rule out any issues with the boost hose(s).

rdboxster

Hello...new to the Cayenne world as I just picked up a slightly used 2016 GTS. Been a low active Boxster forum member since 2011. The CGTS was originally purchased 2 years ago but only had 1900 miles when I took delivery. Driving home from Virginia the vehicle ran great the 1st day handling the West Virginia mountains with ease even in cruse control. The 2nd day we started from Charleston when I started to notice the speed drop off at least 10mph as we climbed the hills on the interstate. I tried downshifting without much change. It wasn't until later in the day I found the boost gage but it did feel like a loss of boost. Watching the boost gage I could see times the boost remained at zero or point something. Other times it acted as I would expect. After the next fuel stop the power was better so I have been attributing to bad fuel. My current plan is to run the tank as low as possible before the next fill.

Finding this thread has me thinking otherwise as the descriptions are similar to what we experienced. I will now watch for a pattern as others are doing.

wkearney99

Has anyone used a DTC scanner (plugs into the OBD2 port under the dash) to check for error codes? After noticing this sort of thing? It'd be interesting to know if any codes were thrown. Especially with how it might related to the unknown knock source.

cdog533

Porsche service admitted the issue was odd, but didn't know why it was doing it.

As mentioned, the car had stopped doing it since that service visit (which included the transfer case replacement).

stiles_s

Add one more to the list of owners experiencing this.

Car: 2016 Cayenne S. 4k miles.

Drive: 200 mile highway drive at relatively high speed.

I noticed the loss of power when leaning into the throttle on gradual right hand bends. then it got worse, to the point where I was having trouble keeping 80mph up a gradual hill on the highway. Hammering the throttle *would* downshift and give me boost, but it really didn't want to give me boost at lower RPMs.

Speeds slowed down and I hit some traffic and the symptoms disappeared. The next day it drove like new.

Also possibly worth noting that I'm seeing the transfer case symptoms as well: slippage and jerkiness when accel @ low speeds, especially cornering.

It's under warranty, so I'm not too stressed about it yet. It'll go to the dealer in hopes of a new transfer case soon.

Tough for the dealer to repro because it needs a good long drive/heat soak, IMO. FWIW, this thing is a long distance weapon as long as it keeps the boost

cdog533

5/22/2017 UPDATE: So, after having zero issues with power loss following my transfer case replacement, I visited the dealer on Friday for an oil change.

Now, the ZERO BOOST situation is BACK. I noticed it immediately in regular (non-sport) mode - that it had basically zero boost off the line under part throttle, making it feel very sluggish. So, I ran it up to speed and sure enough it had zero boost under WOT in 7th & 8th gear (in manual shifting mode). Same problem as I showed in my earlier videos.

Note: It does have 19-20 lbs. of boost if you just floor it and let it kickdown to 3rd or 4th gear; that's not the issue.

I have a call into the dealership to see if they did some kind of software update when it was in on Friday... EDIT: Dealership says no software update. They simply changed oil and reset lights with a service tool.

Any thoughts?

cdog533

5/23/2017 UPDATE: Car seems to be working normally now. No zero boost issues on 30-mile drive. Car operating as normal all around.

Yesterday, when it was doing the zero-boost thing at WOT, it did have a flat 'BLAAAAAAAAA' tone through the exhaust. Someone mentioned earlier in the thread that this is likely a condition of the wastegates being all the way open and just immediately venting the boost. That's what it feels like.

Perhaps it does that in response to detonation or near-detonation conditions. It doesn't want to burn a piston, so it drops all boost at the first sign of pinging. It only happens under conditions which would typically induce detonation - i.e. high load, lots of throttle. I've seen it occurring mostly while lugging the car, running full throttle at relatively low RPM's in high gears; that's where it's easiest to encounter those conditions.

rdboxster

I have not experienced the loss of power since the drive back. Finally had a chance to fill up with non-oxy 91 octane. Close to 300 miles on the tank and the overall drivability has improved. Gas mileage is back up to what we observed early on. I still detect some minor Turbo lag but I also think there is a learning process for both myself and the car. I am used to the V6 diesel which requires very light throttle for great performance and I need to lean into the throttle on the gas engine a bit more. Right now I am attributing to bad fuel or even the possibility of higher levels of ethanol than the engine can handle. Buying gas on the road can be challenging even with the top brands.

wkearney99

I'd very much like to know more about the throttle and shifter 'learning process'.

Since I autocrossed with it last weekend my GTS has taken on a decidedly more aggressive behavior with it's shifting. Which is fine, but I'd like to know to it decides how to recalibrate itself.

cdog533

UPDATE 6/1/2017:

This issue seems to vary from throttle press to throttle press.

Test Procedure:

Keeping it in manual mode and applying wide-open throttle in 7th & 8th gear @ 2,500 rpm, it will make somewhere between 6-13 lbs. of boost. Note that the boost level is not consistent. I don't know why it varies....

Then (under WOT conditions) the boost will either stay solid at that level and gradually climb with the rpms (like it should) OR the boost will trickle down to zero in 1-2 seconds and STAY at zero with my foot pinned to the floor at 3,000 RPMs.

Note that the behavior is not consistent - it can (and does) vary from throttle press to throttle press.

Snipe656

Sorry, just saw this, not been getting email notifications from here in awhile.

I have zero assurances which is why when the vehicle is out of warranty I am trading it in instead of my original plan to keep it a few years beyond. Now considering my issue on the original motor started in 30ish days of ownership, have to check the miles in my log but doubt that was more than 2k-2.5k miles and I think the new engine went in around 8-8.5k that means I have far exceeded the miles it took for that engine. I am sitting in the 18-19k mile range right now, I don't have my log handy to give better mile estimates but do think I posted them before. BTW for me it never took a considerable amount of time to show the issue, it took long distant driving and that holds true for some of the people who posted in this thread early on from what I remember them posting and then from when I contacted them privately for more details.

But this is also why I have been staying in touch with any owner I talked to that said they were told a software fix is coming. Down to just one person who still kept their vehicle and is waiting. They told me a couple weeks ago they were informed a fix is available and should be getting it in upcoming weeks. My thought process has always been that once I see at least one person posting/saying they got a software fix for this then I am going to contact the regional technical manager. Figure the guy gave me his business card, the guy told me this explanation which seemed like a very detailed expansion over the communications I saw between dealer and factory, so I bypass bugging the dealer and instead him first.

I think some people here have the same exact problem since their description seems to mirror symptoms I experienced. I think some people are experiencing something else or maybe combination of same thing with some other issue(s). All I know is best of luck, be a persistent squeaky wheel with them and push hard on Porsche North America via a open case on it. Things really changed for me after I got escalated past the initial person who handled the phone calls at Porsche North America but to get me there took multiple visits to dealerships for the same problem and entire time with an open case. Total pain in the butt and a big part being first person on the phone had the complete stance of "I just don't know how turbos work" for months.

bweSteve

Hey Bill, There's another AutoX 2 weekends from now (June 24th), that I'm hoping to go to with our white 958 CTT. I'd like to talk to you about this in person (& see your GTS). Minta sent me a pic of you at the autocross that weekend back in May (we were in Germany & couldn't be there).

I've been following this thread too, and want to hear some more in person.
=Steve