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I understand there are also two solenoids for the valve lift, but I've purposefully left those alone as I didn't want to just arbitrarily replace parts all in one shot. Made more sense to me to try one thing at a time (and to save some money of course!).
Tempted to, but at the same time, I've already thrown like $800+ and countless hours at this problem.
I'm still trying to burn off the tank of mystery fuel that I added a few weeks ago. Has been a hectic stretch + bad weather, so I've only driven my 911 once or twice in the past few weeks. I'm back into semi-retirement on July 1, will start driving a bunch again
Tempted to, but at the same time, I've already thrown like $800+ and countless hours at this problem.
I'm still trying to burn off the tank of mystery fuel that I added a few weeks ago. Has been a hectic stretch + bad weather, so I've only driven my 911 once or twice in the past few weeks. I'm back into semi-retirement on July 1, will start driving a bunch again
I hear ya. I wonder if there's any correlation to the emissions recall update. Have you done that? I wonder if anyone in this thread with the stumble have done that update..
I hear ya. I wonder if there's any correlation to the emissions recall update. Have you done that? I wonder if anyone in this thread with the stumble have done that update..
Mine is a manual, so there is no recall. I'd gladly update my ECU, even if the result was less total power, to get rid of this issue. Frankly, the car is too fast for the street anyway
My 7MT C2 seems much improved by the Cobb 93 Stage 1 tune. I've only put about 20 miles on it so far, but it's promising. Specifically, the stumble range between 2-3k where it used to feel like it was pulling timing feels much more normal now. I'm not concerned about peak power gains, just drivability. I'm still going to replace the ignition coils and variocam solenoids since I bought them, will report back once I've done that and put >100 miles on the car.
Mine is a manual, so there is no recall. I'd gladly update my ECU, even if the result was less total power, to get rid of this issue. Frankly, the car is too fast for the street anyway
I had declined the recall update AMC0 one last year but I went and did it today. Tech also reset the throttle adaption...well stumble is still there.
Initially he noted it as couldn't replicate issue..but wanted me to drive the car and show it.
Sure enough he felt it as a passenger multiple times and described it as "hesitation/misfire".
To me it feels like the car skips a heart beat..something is off with the timing for a split second.
I gave him the run down on the whole issue and summarized the forum posts to him. He is going to keep the car and log some data. I don't expect much from it but hey..worth a shot at this point.
Whatever the issue is, it will take someone with a knack for solving out of the box issues (not your code reading "mechanics").
Unless of course Porsche has one of their engineers look at the actual code which we know ain't happening.
I had declined the recall update AMC0 one last year but I went and did it today. Tech also reset the throttle adaption...well stumble is still there.
Initially he noted it as couldn't replicate issue..but wanted me to drive the car and show it.
Sure enough he felt it as a passenger multiple times and described it as "hesitation/misfire".
To me it feels like the car skips a heart beat..something is off with the timing for a split second.
I gave him the run down on the whole issue and summarized the forum posts to him. He is going to keep the car and log some data. I don't expect much from it but hey..worth a shot at this point.
Whatever the issue is, it will take someone with a knack for solving out of the box issues (not your code reading "mechanics").
Unless of course Porsche has one of their engineers look at the actual code which we know ain't happening.
It's encouraging that the tech acknowledged the problem. In most cases it's the standard denial of any stumble, or the infamous "they all do that."
It continues to amaze me that the stumble isn't recorded somewhere within the DME. One would think that within the tens of thousands of data points, there would be some obvious indication of the problem.
At any rate, it's promising that they're attempting some troubleshooting. I continue to believe the answer is out there; the question is how much effort PCNA and their dealers are willing to expend.
It's encouraging that the tech acknowledged the problem. In most cases it's the standard denial of any stumble, or the infamous "they all do that."
It continues to amaze me that the stumble isn't recorded somewhere within the DME. One would think that within the tens of thousands of data points, there would be some obvious indication of the problem.
At any rate, it's promising that they're attempting some troubleshooting. I continue to believe the answer is out there; the question is how much effort PCNA and their dealers are willing to expend.
Yes it felt good to be validated that there is an issue. He stated "I test drove and I couldn't replicate it". But he goes..I hate to just give the car back to you so let's go drive it together.
I know exactly how to replicate it and I looked over it at him when it first happened and asked..you felt that? He goes up. There it is.
And yes how does this not throw a code? Or is it recorded as a misfire (which there are a few of but not enough IMO to show it's a problem).
Which brings me to ...it's a bug in the code or a correction by the DME based on X parameters from X sensors in X cars. The answer is out there for sure but it will take some real sherlock holmes work to find the parameter that's off.
i've had my 991.1 MT since 2018 and i haven't experienced this issue. sometimes its a little rough in the first 30 seconds of driving if it's cold out and the car is cold but that's it.
what i did have in an old car was a bad seat rack which caused a human-chair-inertia induced stumble.
(the force of the car going forward pushed me back a bit, which caused me to release the throttle a bit, which slowed the car, causing inertia me to move forward and press the throttle a bit.)
I reset the ETCS using my PORS V2.0. Seems to have solved stumble - well at least temporarily, but hopefully long term. Will probably reset it each year when I do my oil change and reset the oil service light. Takes 5 seconds.
I reset the ETCS using my PORS V2.0. Seems to have solved stumble - well at least temporarily, but hopefully long term. Will probably reset it each year when I do my oil change and reset the oil service light. Takes 5 seconds.
Interesting. I'll have to hook up that tool and try the same thing.
I pulled the fuse in the passenger footwell that I think was for the ECU, and left it sitting that way for about a minute. Hard to tell with 100% certainty as I only had the French manual at hand
Car drove brilliantly this morning. Pretty sure it's not a placebo - I'm too obsessed with how the stumble presents itself and feels.
Dealer visit was useless. he printed me some screenshots of PIWIS and said look all good!
service guy and tech both rode with me and acknowledged the issue and wished me best of luck in finding the solution. haha.....
going to have to get my hands on a PIWIS and start doing my own data capture.
question is what to graph/log. so many inputs/outputs...here's a screenshot i found from a cayman's DME.
I tried logging the pedal value (%) and the throttle plate angle.
It's interesting to see a dip (starting at the grey line) or change in value on the throttle plate angle when the pedal value is relatively the same..
I can also hear an audible diff some kind of pop/puff as this happens...
So question is, is the DME doing this on purpose based on another sensor value or is TB acting bad..?
TOP BOX: PEDAL VALUE LEFT, THROTTLE PLATE ANGLE RIGHT
BOTTOM: THROTTLE VALUE POT 1 (LEFT) AND POT 2 (RIGHT)
I logged the same data with the car idling. Every so often I feel a little roughness/stutter and on the graph i see the throttle angle value change a little bit.
I know folks have replaced TB without much diff but I am wondering if it's worth a try to eliminate it as a potential cause.
I also ran all the short term tests available in the PIWIS under DME. all passed. When I did the Valve lift ones, I could feel the same stutter/tug. Correlation to TB issue above or causation.....not sure.
06-18-2023, 07:41 PM
