Data for Engine shudder/2500rpm issues
09-27-2014, 09:11 PM
#16
How long do you think your engine's going to last without a nice thick layer of carbon build-up protecting pistons, valves and plugs?
09-27-2014, 09:37 PM
#18
Burning Brakes
Throttle mapping/ecu issues are one thing, but improperly balanced crankshafts are another entirely. If it's the latter, I wonder what the effect will be on higher mileage out of warranty cars. Could end up being another 996 debacle.
09-27-2014, 09:58 PM
#19
Rennlist Member
Wein.
There are two distinct scenarios.
1. When accelerating (moderate load) in 2nd and 3rd gear, you feel a very obvious shudder @2500 along with a very brief lunge as the power loss occurs for a split second, before returning.
If you drive hard, the dead spot is not as noticeable. Sadly this is not an option with daily city driving.
2. When cruising on the highway at the 2500 rpm spot, you feel a constant tugging sensation as if the engine is not getting a steady supply of fuel or the correct mixture. It has been described a fishing line tug, or as if the engine is "hunting".
I hope this helps.
There are two distinct scenarios.
1. When accelerating (moderate load) in 2nd and 3rd gear, you feel a very obvious shudder @2500 along with a very brief lunge as the power loss occurs for a split second, before returning.
If you drive hard, the dead spot is not as noticeable. Sadly this is not an option with daily city driving.
2. When cruising on the highway at the 2500 rpm spot, you feel a constant tugging sensation as if the engine is not getting a steady supply of fuel or the correct mixture. It has been described a fishing line tug, or as if the engine is "hunting".
I hope this helps.
09-28-2014, 12:22 AM
#20
Rennlist Member
I'm not here to argue boys.
The sensation that is being described is being caused by the mechanical imbalance. If someone earlier claimed they were experiencing an issue like this and it went away temporarily it quite possibly could be another issue.
Like I said, I'm not here to argue, I'm just sharing the details of a conversation I had with another Porsche owner and an acquaintance that recently spent a year of internship at Stuttgart. It's an amazingly small town.
The guy who stars in the YouTube video posted here is obviously upset. Unfortunately, that's the nature of the PDK.
The sensation that is being described is being caused by the mechanical imbalance. If someone earlier claimed they were experiencing an issue like this and it went away temporarily it quite possibly could be another issue.
Like I said, I'm not here to argue, I'm just sharing the details of a conversation I had with another Porsche owner and an acquaintance that recently spent a year of internship at Stuttgart. It's an amazingly small town.
The guy who stars in the YouTube video posted here is obviously upset. Unfortunately, that's the nature of the PDK.
09-28-2014, 12:27 AM
#21
Rennlist Member
Oh, and I forgot to mention. Duxsi described what has been the issue since 2012. It's not all the cars. For those of you that are experiencing this issue, put your trans in neutral and slowly bring up the revs through 2,300-3,000 rpm and you will see what I'm talking about. It's not a fuel delivery or management issue. It's going to be more noticeable in some cars. It will be obvious.
09-28-2014, 12:29 AM
#22
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I don't think this issue is limited to the PDK. Here is a VERSION 1.0 of my questionnaire. If you have any additional things you want answered please PM me and I will add them and then hopefully in the next day or two I will post the FINAL version of this for people to start filling out. I am just trying to help us ask the right questions to narrow this down.
Thanks
Thanks
09-28-2014, 12:55 AM
#23
Rennlist Member
I'm not here to argue boys.
The sensation that is being described is being caused by the mechanical imbalance. If someone earlier claimed they were experiencing an issue like this and it went away temporarily it quite possibly could be another issue.
Like I said, I'm not here to argue, I'm just sharing the details of a conversation I had with another Porsche owner and an acquaintance that recently spent a year of internship at Stuttgart. It's an amazingly small town.
The guy who stars in the YouTube video posted here is obviously upset. Unfortunately, that's the nature of the PDK.
The sensation that is being described is being caused by the mechanical imbalance. If someone earlier claimed they were experiencing an issue like this and it went away temporarily it quite possibly could be another issue.
Like I said, I'm not here to argue, I'm just sharing the details of a conversation I had with another Porsche owner and an acquaintance that recently spent a year of internship at Stuttgart. It's an amazingly small town.
The guy who stars in the YouTube video posted here is obviously upset. Unfortunately, that's the nature of the PDK.
In God we trust. All others bring data. Actually that goes for God too.
09-28-2014, 01:20 AM
#24
Rennlist Member
Noah.
These are two totally different issues. I don't think you guys get it.
The stumble issue is crankshaft related.
The guy that posted a link to the guy describing his throttle delay in his PDS C2S car shouldn't have been posted here.
I haven't seen anyone complaining about the stumble issue with a manual car.
The stumble issue is even more noticeable when the transmission is under load ( when the car is in gear and being driven) The stumble issue complaint has nothing to do with the transmission. It's internal in the engine. Months ago there was speculation that the stumble issue was an engine management problem. Around 6 months ago there were reports about owners receiving a software update when their cars were brought in for regular service (10k mile) oil change or a two year oil change for owners that don't have 10k miles BUT 2 years.
Anyway, within the software update is a modification with how and when the PDK shifts around that RPM range in an attempt to mask the problem.
Believe what you want. It ended up being an hour long conversation during the ride home from the airport. He was stuck with me in my car so he didn't have a choice but to answer a few questions of mine.
These are two totally different issues. I don't think you guys get it.
The stumble issue is crankshaft related.
The guy that posted a link to the guy describing his throttle delay in his PDS C2S car shouldn't have been posted here.
I haven't seen anyone complaining about the stumble issue with a manual car.
The stumble issue is even more noticeable when the transmission is under load ( when the car is in gear and being driven) The stumble issue complaint has nothing to do with the transmission. It's internal in the engine. Months ago there was speculation that the stumble issue was an engine management problem. Around 6 months ago there were reports about owners receiving a software update when their cars were brought in for regular service (10k mile) oil change or a two year oil change for owners that don't have 10k miles BUT 2 years.
Anyway, within the software update is a modification with how and when the PDK shifts around that RPM range in an attempt to mask the problem.
Believe what you want. It ended up being an hour long conversation during the ride home from the airport. He was stuck with me in my car so he didn't have a choice but to answer a few questions of mine.
09-28-2014, 01:41 AM
#25
Rennlist Member
Sorry Weim.
I don't think I should have chimed in with the info I have. My car doesn't have the issue. 2013 but June build so almost a 14 by model year.
I should be clear that I'm sure the MT cars have the same issue. There just isn't as many MT cars out there and that's most likely the reason we haven't heard about it from them.
Those of you that know you have the "stumble" issue go right out and do what I said to do. He actually called it a harmonic imbalance. Again, it will be very obvious. Even in the cars where the stumble isn't as pronounced, you will notice it at a complete stop, in neutral, left foot on the brake or parking brake on.
I don't think I should have chimed in with the info I have. My car doesn't have the issue. 2013 but June build so almost a 14 by model year.
I should be clear that I'm sure the MT cars have the same issue. There just isn't as many MT cars out there and that's most likely the reason we haven't heard about it from them.
Those of you that know you have the "stumble" issue go right out and do what I said to do. He actually called it a harmonic imbalance. Again, it will be very obvious. Even in the cars where the stumble isn't as pronounced, you will notice it at a complete stop, in neutral, left foot on the brake or parking brake on.
09-28-2014, 02:29 AM
#26
Marcus, it happens on MT cars. I'm a 7-Speed MT, C2S stumbler.
What are you trying to demonstrate by slowly bring up the revs through 2,300-3,000 rpm?
I did this and nothing happened.
The sensation that we feel is closer to fuel starvation as opposed to a harmonic imbalance.
What are you trying to demonstrate by slowly bring up the revs through 2,300-3,000 rpm?
I did this and nothing happened.
The sensation that we feel is closer to fuel starvation as opposed to a harmonic imbalance.
09-28-2014, 03:01 AM
#28
Marcus, it happens on MT cars. I'm a 7-Speed MT, C2S stumbler.
What are you trying to demonstrate by slowly bring up the revs through 2,300-3,000 rpm?
I did this and nothing happened.
The sensation that we feel is closer to fuel starvation as opposed to a harmonic imbalance.
What are you trying to demonstrate by slowly bring up the revs through 2,300-3,000 rpm?
I did this and nothing happened.
The sensation that we feel is closer to fuel starvation as opposed to a harmonic imbalance.
09-28-2014, 06:29 AM
#29
Rennlist Member
Ok... My 2 pennies.
My experience is spot on with duxsi comments. Started day 1 and hasn't got any worse after 7000 miles (better if anything but still there). I can't describe it any better than duxsi. Feels like temporary fuel starvation resulting in a split second hesitation when going up through the range with light load
I also have a slight crankshaft imbalance which does indeed resonate through the 2-3krpm range in neutral but this is nowhere near as point specific as the hesitation phenomena which would be evidenced on a Campbell plot.
I could be wrong but my experience tells me there are 2 coincident but separate issues at play... The hesitation bothers me a bit.... The resonance doesn't as it is barely noticeable when driving...
My experience is spot on with duxsi comments. Started day 1 and hasn't got any worse after 7000 miles (better if anything but still there). I can't describe it any better than duxsi. Feels like temporary fuel starvation resulting in a split second hesitation when going up through the range with light load
I also have a slight crankshaft imbalance which does indeed resonate through the 2-3krpm range in neutral but this is nowhere near as point specific as the hesitation phenomena which would be evidenced on a Campbell plot.
I could be wrong but my experience tells me there are 2 coincident but separate issues at play... The hesitation bothers me a bit.... The resonance doesn't as it is barely noticeable when driving...
