That's an interesting approach! Will try it out and report back here...

 

ya I can reproduce it by letting RPM drop and climbing again. that's how i have been able to graph things.

I have to say my stumble has decreased in frequency when I try to replicate it since the camshaft sensor replacement. Just when I think it's fixed, it reminds me it's still an issue compared to...."there it is....there it is...there it is..."

I just replaced the crankshaft sensor with the latest and greatest one...(original one was 2013 date code with original part#)
New part is from 2022 and porsche has revised it 3 or 4 times now. no difference in stumble.
EDIT: removed it. put the old one back in since it made no difference. money saved for now haha..

noticed something else: when downshifting, and if RPM goes from 3 to 4K, at the 3500rpm mark, i can feel a little surge randomly. we know thats a popular variocam transition area.
the more and more I think about this, I would say there's probably a prominent transition at the RPMs everyone is experiencing the stumble. why it's smooth for some and not for others? no clue.
why does PSM off fix it for a few? who knows.

Maybe the drive link test and the camshaft solenoid not responding for the first few times is a clue.....an electrical clue....and we know electrical gremlins relating to coil packs show up as PSM faults..so something in this vicinity..i am just thinking out loud of how variocam and PSM is related.

also the same little stutter is felt when I do the valve lift test. i have these on order to complete my overhaul of the variocam triad (camshaft solenoid (400 bucks), camshaft sensors (70), valve lift solenoids (300).

here's another symptom for me:
during cold starts, while idling, there's def a little unevenness every 5-10 secs you hear a little something. check out this clip....you should hear it a little pause/pop/stutter..whatever..

graph of the AUDIO clip...

 

For some reason I can't play the sound sajan...

 

reuploaded it.

 

I put 800 miles on my car (Cobb tune, new variocam solenoids and coils, toggled PSM off/on) in the mountains the past few weeks. In Sport or Sport Plus it feels great lately. I didn't have any kind of stumble complaints on that trip. I think the Cobb tune did improve things for me. In normal it's a bit more anemic so I just haven't been using it like that except for steady state highway miles.

I have a Porsche dealer appt in a couple of weeks for service and a small laundry list of things, I'm going to flash back to stock and see if I notice the hesitation happening again. If so I'll get them to look at it. But the difference between stock tune normal mode and Cobb tune sport mode is enough for me to be happy.

The car is also just so much happier in its element being driven hard that I think the best solution is just not driving it unless I have a proper drive for it. For the boring drives my EV is a better tool for the job anyway. I bought a PIWIS setup but haven't had the time or motivation to use it to dig further.

 

Hello everyone, I "Stumbled" across this thread from another member linking me to it...

I have a 2018 Macan GTS and have also the same stumble issue that you guys are describing, for me it happens in the 1600-2200 rpm range usually and it feels like the clutch is opened and closed for a split second.
This issue for us Macan owners seems to happen only on the 2017 and 2018 6 cylinder models (S and GTS) when they get beyond roughly 40k miles. (From 2018 and lower the 6 cylinder models are all Porsche engines, from 2019 and beyond the engines are made by Audi and there are no stumbles reported with those)
We only have PDK unfortunately and I was thinking it was trans/mechatronics related, (As the stumble feels like a quick PDK shift for a brief second) but you folks have manuals with the issue so it may not be PDK related.

I hope you don't mind me piggybacking on this thread as the testing methodology you guys have applied here is amazing. Hats off to all of you...
I have been replacing sensors as well on my end to no avail, this stumble for the Macans happens right in the range I normally drive at so it happens all the time and is pretty frustrating.

I have yet to try the PSM on/off trick but I will later this afternoon as after reading through much of this thread I can see how the PSM might be the culprit. (Bad wheel sensors?)

Has anyone tried to just unplug the PSM ECU? I am sure the dash will light up like a christmas tree with lights but is the car drivable with all those faults? I suspect it would be with lots of warning on the dash, but this would tell us if the PSM was the culprit with it really off (As you know its never really off otherwise)

Other things to note is that my Macan is under CPO warranty until March 2024 and has been to the Porsche dealer twice for this issue, they can easily reproduce the issue and have noted that another 2018 Macan S they had at the time also did it.
However both times they told me that it's just how these vehicles are and its considered normal. So I have been chasing it at my own expense. If I can find a reason for failure or 100% point it to software I am certainly going back in to the dealer once I can pinpoint the problem for them.

 

you might be onto something with the temperature correlation.
I noticed it’s practically non existent when the temp was 60 F too! It wasn’t humid. Clean crisp air.

And maybe it’s not the temp…maybe it’s the barometric pressure.

which brings us to MAP sensor………

has anyone replaced this?

 

I got a 30 minute ride along in my car with a 20yr Porsche dealer tech. On the factory tune, mostly in normal mode. He drove the whole time. I noticed some times where it felt to me like it was pulling timing; he said it was normal operation of the 3.4L which is fairly weak in the 2-3k RPM area near the Variocam transition. In his opinion, the engine is just high strung and I should try to keep revs up and not expect perfectly smooth operation from it down low.

It's hard for us all here because we mostly only know what our own cars feel like. There may be a range of how badly this issue shows up for people -- in my case I'm inclined to trust the tech that my car feels normal, and also take the couple of steps that I found made it better -- reinstalling my 93 tune and keeping it in Sport/Sport Plus. Maybe a set of headers to help add a little torque.

He was also a bit surprised that I'd replaced the Variocam solenoids already and said that was the only part they've ever changed for customers in relation to this complaint.

 

This weekend I was on a long drive with lots of scenarios (highway, mountain road with tight bends). Remembering this idea (and because it was warm & dry) I turned off PSM and the engine was not showing the dreaded stumbling between 1500 and 2k RPM. I suspect the PSM interference with the ECU in the standard setting (on) is leading to a bad side effect in terms of missing smoothness. Has anyone with the proper analysis gear recorded the firing timings in this scenario? There must be visible delays IMHO…

 

Last month, I replaced the IPD air intake and accidentally damaged the air pressure sensor. The engine displayed a yellow warning light, showing error codes P0113 and P0114, and it was prone to stumbling. Later, I purchased a new air pressure sensor, and the symptoms disappeared.

A careful inspection of the intake volume and intake temperature might be a direction to consider as well.

 

Yes. I drove the car a ton through different terrains, temperature, elevations recently and there were distinct periods where I didn't feel the stumble. and trust me, I know when it happens and I can make it happen on command. I tried for many miles and it was smooth. Once I got to the Texas heat and humidity, stumble galore.

Other than temperature (60 vs 100+) I was using 91 octane (only choice) vs. 93 in Texas.

I have two new variocam solenoids sitting here. I will replace them and see if it makes a diff...my guess is no. I am going to order a MAP sensor next. Worth trying for $40.

EDIT: Pressure sensor on the intake manifold (detects intake manifold pressure and intake air temperature)

 

Just thinking ... if people are have success with pushing the PASM PSM button off/on and the stumble is "basically gone"...could the issue be the PASM PSM computer? Anybody on this thread still having issues after installing a DSC controller?
Is the PASM PSM computer sending out "bad code" to the DME...? Just a thought.

 

not PASM - suspension management.

what folks are switching off is PSM - stability management

i replaced the manifold sensor but I noticed I have to reset the adaption for the sensor AND do a throttle adaption. the throttle adaption needs to be done between 5 - 30 C intake temperature. it's 8000 degrees here so I have to wait lol..

I also noticed the dash temperature (coming from the sensor in the front bumper area), intake temp (manifold), engine temp are about 3-4 deg F higher than what I was able to measure with two diff thermometers. interesting. it's like everything is calibrated higher on the car..

 

I just came upon (I won't say stumbled across) this thread. After reading through it entirely, I wanted to add my experience with a stumble in my 2016 981 GT4. I have a consistent and repeatable stumble at just under 3000 rpm regardless of engine temperature. This happens anytime the engine rpm's pass through this threshold regardless of the gear and or speed. It is hardly perceptible under hard acceleration due to passing through the range so quickly but is noticeable otherwise. Anytime I'm above 3000 rpm and I release the throttle so the engine drops below 2800 and accelerate through 3000 rpm, I will get a single stumble like a misfire. This is regardless of the engine temperature. The engine runs very strongly at all other points above and below 3000 otherwise.

Even though the configuration and modifications to my car eliminate a number suspected root causes, I still have a stumble. Specifically, my car has a manual transmission and the following aftermarket mods:

• Softronic Tune
• m&m fvd full race exhaust with mufflers and longtube catless headers (no valves)
• PSE switch disabled by plugging the vacuum line
• Soler Performance Throttle Controller

With that said, I had actually thought my issue was the result of the Softronic tune. This is the third car on which I have installed a Softronic tune - the first two were a 987.1 and 987.1, and have not had and issue otherwise. I did speak with Scott about it and he said that the tune should not have any impact. If I do figure out the root cause, I will report back here.

 

@licheng Any update from your fix?
Thx