Interesting.. it tends to imply that the problem is somehow related to the "learning" that goes on by the Engine/ECU. And if it is based on learned behavior might explain the wide variation and difference in ways it manifests itself among different drivers.

It's funny, I see it only occasionally... I had been thinking to myself just a couple of days ago that I was imagining the problem since it hadn't happened recently. Then I was going around the corner and hit the throttle a little harder than my normal (but not as hard as I would if I was being real aggressive.. and for a brief moment it felt limp....

I may experiment by disconnecting the battery.. but my problem is that it is just not as repeatable as others have reported.. I'm not sure if that is a good or bad thing anymore.

 

I have a 2014 C4S and does the hesitation as well. I mainly notice it on the first drive on second gear accelerating.

 

Yup, that's the dreaded stumble.
I am STILL working on this with PCNA and much to their shagrin I simply will not let this issue go.

 

Yep, that's it. Welcome to the club!

After much empirical evidence, mine feels worse in 2nd and 3rd gears, and appears in the 2-3K RPM range, most of the time near 2300 RPM, but then I get a big jolt at 3K RPM. The interesting thing to me is that after the first big jolt at 3K RPM, it seems to smooth out a bit - it's like the VarioCam is stuck at first, then loosens up.

 

Unfortunately, it's a club that most owners with the problem don't want to belong to. And, the sad truth is that PCNA refuses to acknowledge the issue, let alone fix it. The solution obviously must come from a source outside of Porsche.

Here's a thought: say 100 owners with the problem pony up $100 each and offer a $10,000 reward to anyone that can identify the cause of the stumble. Might be money well spent.

 

I would definitely contribute to that fund. Hell, I'll pony up $200 towards that :-).

I'm still reeling from a horrible experience I had trying to track this problem down. I took the car to a different dealer in my area, they claimed there was nothing wrong, and in the process they put a nice scratch on the front of my car. So I've got that going for me...

 

If you drive the every living hell out of the car is it o.k. the next time you start it and then it slowly reverts to stumbling?

 

I really thought this thread was dead. Can't believe no one has figured out what the issue is with engine stumble. Thank God my 2014 Carrera does not have it. Good luck to all of you who do.

 

No - makes no difference.
However, resetting the DME or disconnecting the battery long enough makes the problem ago away for about 24 hrs.

As much as I love the idea of the "fix-it-fund", it does little to address the warranty issues that we would no doubt be facing as a result.

The quest continues..

 

I say pin pointing what the root cause is is the first step in proceeding forward. You need a definite cause/effect.

Obviously Porsche only sees this as a urban legend at this point and finds it easy to dismiss it.

 

I'm not so sure PCNA considers it as an urban legend. I believe they know it's a problem of varying degrees for a small number of owners, and they either have no idea how to fix it, or are concerned about the associated repair costs. In either case, the easiest course of action for them is deny, deny, deny.

 

I agree that they know the cause, but dismiss it as urban legend because of the points you stated.

But for an owner with this problem not having a definite diagnosis and cause they have little to go by rather than joy rides with service advisers who are clueless.

For PCNA to fess up to it, the cause needs to be exposed. So far, they may be the only ones that know what it is. Nobody here has any concrete evidence as to what is causing this.

I find it bizarre nobody has had an independent knowledgeable shop try and figure it out yet.

 

The more time they buy the more warranties will start expiring. Good strategy.

 

While I originally thought the problem must be of mechanical nature somewhere in the VarioCam system, the fact that the problem disappears after disconnecting the battery/resetting the ECU makes me think otherwise. Since the ECU and associated firmware/software are proprietary, an indie would have a hard time troubleshooting.

 

It's software related.
After running hundred of tests, with different fuels, temperatures, hard vs. soft driving, auto-idle overrides, replaced fuel caps, etc etc etc, nothing made a difference EXCEPT a dealer DME reset or a prolonged battery disconnect.

Both of these resulted in crisper and far more linear powerband every single time, only to have the stumble return approximately 24 hrs later.

PS. Not acknowledging something does not make it an urban legend - it merely makes you an unethical ******* of a car company. Ask Nick Murray...