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TL;DR: Stumbling is momentary blips, jumps, jitters in acceleration usually in the 1500-3500 rpm range affecting PDK and manual. Usually more common in lower gears, no noticeable difference in regular vs sport modes for most people. All manner of parts have been replaced with no lasting improvement for most people. Porsche says its “normal.”
It's not just 991.1 cars that have a stumble or stutter! My 2017 991.2 C2S has had one since the Porsche dealership performed the major service including the spark plugs a couple of years ago at 27k miles. i'm now past 38K miles and the stutter occurs when maintaining or slightly accelerating in 6 or 7 gear at low engine RPM [about 1500] and ascending a slight grade in the road. Dealer determined that much of the problem was due to the Coolant Pump leaking and coolant contaminating the vacuum control lines and Valve Bliock. Those were recently replaced, and now I do not get any CEL but the occasional stunble is still present. No issues if I drive more aggressively and faster, but then I wouldn't have a driver's license for very long.
I have a Softronic tune on my car and it stumbles. I've learned to live with it. It was a little disconcerting the first dozen or so times it occurred. Lumbering along and hit the accelerator and the car hesitates / stumbles for a moment before responding to the input. I can tell you it also happened with the COBB tune.
Has no one replaced the gas pedal? Have read in other places that the stumble disappeared on 991.1's when the gas pedal (with potentiometer or whatever it uses to work) was replaced.
Has no one replaced the gas pedal? Have read in other places that the stumble disappeared on 991.1's when the gas pedal (with potentiometer or whatever it uses to work) was replaced.
My 3.8 C2S 991.1 has no stumble, btw.
I haven’t, but have heard the same thing. That would be amazing if that’s all it was…
I haven’t, but have heard the same thing. That would be amazing if that’s all it was…
I have first hand knowledge that replacing the accelerator pedal cures the stumble. I also have first hand knowledge that the stumble returns within a day or two.
I had the same experience after replacing the O2 sensors. Even disconnecting the battery overnight can cure the stumble for a short period of time.
Unfortunately, the DME/ECU always has the final say in the matter, and reverts to its evil ways.
I have first hand knowledge that replacing the accelerator pedal cures the stumble. I also have first hand knowledge that the stumble returns within a day or two.
I had the same experience after replacing the O2 sensors. Even disconnecting the battery overnight can cure the stumble for a short period of time.
Unfortunately, the DME/ECU always has the final say in the matter, and reverts to its evil ways.
So all of the jittery/jumpiness goes away for a bit and then comes back? After how many miles?
So all of the jittery/jumpiness goes away for a bit and then comes back? After how many miles?
As I've never driven a PDK car with the stumble, I'm not so sure we're talking about the same issue. In my manual trans car, the stumble is very brief and very distinct. Just a nano second of uneven engine acceleration. Always occurs at the same exact rpm of 2400. And oddly, it usually varies in intensity from day to day.
As I've never driven a PDK car with the stumble, I'm not so sure we're talking about the same issue. In my manual trans car, the stumble is very brief and very distinct. Just a nano second of uneven engine acceleration. Always occurs at the same exact rpm of 2400. And oddly, it usually varies in intensity from day to day.
Mine happens between 1500-3500 rpm and feels like the car is jerking through the acceleration. Like it hesitates for a brief second and then the acceleration kicks back in.
I have a Softronic tune on my car and it stumbles. I've learned to live with it. It was a little disconcerting the first dozen or so times it occurred. Lumbering along and hit the accelerator and the car hesitates / stumbles for a moment before responding to the input. I can tell you it also happened with the COBB tune.
Martin
Hummm interesting as mine went away with the tune...but I have a full SOUL exhaust (headers/valved exhaust) so I wonder if it has something to do with that because the hesitation is gone in mine
I had it in my turbo s , any sort of boost leak will cause it in my opinion, but my opinion is o it based on my experience of my car .
I changed this part here which I blew off. It’s part of the secondary air pump and it’s now has no stumble. Edit , there is 2 of these valves in my engine . I just did the faulty one
06-27-2024 | 01:32 PM
