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Engine stumble/hesitation around 2500 RPM?

 
  #61  
Old 10-24-2013, 10:51 AM
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Originally Posted by ChuckJ View Post
I was thinking it was the variable intake in the S that was not working properly.
Hi Chuck,
Thanks for your input. However, a friend of mine with a 997.1 C2 has the same problem.

I really hope a 991 owner with this problem will use the info I posted above and pressure his dealer for a resolution.

Cheers
 
  #62  
Old 10-24-2013, 12:22 PM
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The problem is the lack of fault codes.
The dealership will not go on a fishing exercise, because in their world EVERYTHING has to throw a fault code. Without one there simply cannot be problem - no matter how apparent the problem is.

It would only be done by a independent / turner who has the ability to engage in deductive thinking.

The 997 folks suffer a similar fate, and were also told that it's "normal".
 
  #63  
Old 10-27-2013, 07:44 AM
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I have noticed the same thing under light throttle, right around 2500-2800 rpm. It's very slight but noticeable. If I'm under hard accel it's not there. I think maybe you could be shifting the cam profiles.
 
  #64  
Old 10-27-2013, 08:56 AM
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Gave this a try yesterday in my 2014 911S

No noticeable stall/delay between 2000rpm and 3000rpm, but truth be told, the car isn't exactly torquey below 3000rpm anyway.

Are we not confusing a gradual increase in power as the rev needle increases from 2000 to 2500 and 2800 and up? As I said, no delay, but the car certainly pulls less at 2000rpm than it does at 2800rpm.
 
  #65  
Old 10-27-2013, 09:03 AM
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No - we're definitely not confused.
It's not a matter of pulling less. We are talking about a distinct shudder under gentle / moderate acceleration.
It feels like it's not getting petrol for a split second and then the power returns.

If you floor the gas pedal, you will not feel it.
Thankfully your car is most probably fine.
 
  #66  
Old 10-27-2013, 10:02 AM
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Originally Posted by dux View Post
No - we're definitely not confused.
No insult intended, perhaps using the word "confusing" was ill-chosen.

Originally Posted by dux View Post
It's not a matter of pulling less. We are talking about a distinct shudder under gentle / moderate acceleration.
It feels like it's not getting petrol for a split second and then the power returns.

If you floor the gas pedal, you will not feel it.
Thankfully your car is most probably fine.
My model build date was sometime in June/early-July - whatever it is can only be something that Porsche are aware of and rectified or must be environmental - possibly fuel quality as some have mentioned.

Good luck, I'd be hounding my dealer if it was something I could demonstrate on my car but not on one of their demo cars.
 
  #67  
Old 10-27-2013, 10:34 AM
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The Variocam bump on my 997.2 was so bad that at times it felt and sounded exactly like a significant mis-fire. And in fact, when it occurred in a tunnel you could hear it pop. The stumble on my 991 thankfully is nowhere near as bad, but still noticeable.

When considering the complexity of the system, it's not surprising to me that the cam profile changeover can be less than perfectly smooth. What is surprising however, is that the Variocam system has been in use since 2001 and apparently is still a work in progress.

 
  #68  
Old 10-27-2013, 11:04 AM
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Originally Posted by MacAna View Post
No insult intended, perhaps using the word "confusing" was ill-chosen.
No offense was taken, but thank you for clarifying.
 
  #69  
Old 12-13-2013, 11:56 PM
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Hey everyone. I was directed to this thread by mtony over on rennlist. I picked up my 2014 911 Carrera S MT 2 weeks ago and started noticing this problem. Basically If I am in 2nd gear at 2,000 rpm and get on the gas a little bit the car feels like it is going over small bumps. It basically feels like noticeable skips in smooth power delivery just as others on here have described. Originally I thought I had not broken in the car properly and was all worried. I am a little more relieved now knowing it's probably not something I caused.
 
  #70  
Old 12-14-2013, 07:44 AM
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Originally Posted by LiteWait View Post
Hey everyone. I was directed to this thread by mtony over on rennlist. I picked up my 2014 911 Carrera S MT 2 weeks ago and started noticing this problem. Basically If I am in 2nd gear at 2,000 rpm and get on the gas a little bit the car feels like it is going over small bumps. It basically feels like noticeable skips in smooth power delivery just as others on here have described. Originally I thought I had not broken in the car properly and was all worried. I am a little more relieved now knowing it's probably not something I caused.
This might happen when it's cold, the first couple minutes, but if it happens after that, it needs to go in for service techs to look at it.

ChuckJ
 
  #71  
Old 12-15-2013, 09:11 AM
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I've had the same issue on my 2012 S. A definite hesitation around 3200 RPM. I took it in to the dealer who also noticed the anomaly and upgraded the firmware to the newest version. It has remapped the PDK slightly but I'm still noticing the hesitation. I'll be taking it in again. I do remember the tech. talking about variable valve timing changes.
 
  #72  
Old 03-04-2014, 08:21 PM
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Originally Posted by mtony View Post
I too have the stumble between 2500 and 3000 RPM on my recently delivered C2S. I remembered seeing this post and ignoring it when I saw it, but now it's happening to my car too, so I was checking to see if anyone had a solution yet.
I have a 2014 991 C2S ( 1,200 miles on her )and are having the exact same problems, i have taken it to the dealer, picked up the Shop Foreman and took him for a drive. He felt the issues and would look into it.. They ended updating the DME and reset all the values. It seems to have worked for 24 hours then started again... I'm beyond frustrated and are loosing my patience . It also stinks of oil when driven. Did you make any progress?
Thanks again for your help!R
 
  #73  
Old 03-04-2014, 08:43 PM
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Originally Posted by Bowen044 View Post
They ended updating the DME and reset all the values. It seems to have worked for 24 hours then started again...
This is the EXACT thing that happened to me. The car drove phenomenally for 24 hrs after updates and resets and then back to the usual.
So it is obviously something that can be fixed.
 
  #74  
Old 03-05-2014, 07:04 AM
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I have a 2014 S with 7 speed MT and have noticed the same hesitation between 200 and 300 RPM...doesn't seem to matter if I'm in 2nd or 3rd either.

<tracking thread>
 
  #75  
Old 03-05-2014, 07:13 AM
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Originally Posted by Bowen044 View Post
I have a 2014 991 C2S ( 1,200 miles on her )and are having the exact same problems, i have taken it to the dealer, picked up the Shop Foreman and took him for a drive. He felt the issues and would look into it.. They ended updating the DME and reset all the values. It seems to have worked for 24 hours then started again... I'm beyond frustrated and are loosing my patience . It also stinks of oil when driven. Did you make any progress?
Thanks again for your help!R
I was basically told that they all do that, and have since tried to drive it in a manner where I don't feel it as much. You can avoid it by either accelerating harder through 3000 RPMs or by short shifting below 2500 RPMs.
 

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