Very best of luck... I know how much you covet your car... I have a minor stutter with all the same symptoms but mild.... I hope for so many on here you get a fix, not just an excuse. I'm guessing the reluctance to acknowledge the problem relates to their warranty bill, not their technical expertise... Apparently the GT3 debacle cost circa £120m ... Enough to challenge even Porsches P&L!

 

My gut tells me that PCNA is very aware of the fact that some cars do indeed have a problem with the stumble. My gut also tells me that PCNA will do everything in their power to sweep this under the rug and avoid a potentially costly fix. For how many years did they refuse to admit to the IMS problem?

 

Start posting it on PCNA's Facebook page

 

All in good time Grasshopper.
First you must learn to ****** the pebble...

 

I'm back from the dealership 3 hours later. It's fixed!


Just kidding... It went even worse than I had planned. When I got there the service advisor immediately started arguing with me as I attempted to explain the issue. He said they weren't confindent in what the other dealership did, so they wanted to do the same thing. Scan for codes, do a DME update, and spot check. I tried to explain they would be wasting their time. As soon as I referred to my research, they immediately dismissed "the internet." I wised up an started referring to all of you as my "friends." Non-enthusiast employeed don't understand us.

So I went for a ride with the Service Manager. Super nice guy, but I could tell he thought it was normal operation. He just wasn't saying it directly to me. I'm driving in 8:00 AM Orlando traffic, so it was very difficult to demonstrate.

When we get back, he leveled with me. He said he'd be happy to chase this rabbit (within limits), but when he compiles a log pulled from the car to email to P-Tech, the first thing Porsche is going to ask about are aftermarket parts. He suggested before we do anything I need to get the factory exhaust back on the car. I agreed that made sense other than the fact that dozens of us are having the same problem. I didn't argue the point and understand the reasoning.

We decided it didn't make sense to leave my car to do the normal checks. I may be making the wrong assumptions, but I don't think he really thought I had a problem. I think he was just hearing me. I didn't get the sense they were going to spend too much time on it. So there is no way they are going to figure out the problem.

I drove the 55 miles back home with my tail between my legs. So a waste of 110 miles and 3 1/2 hours of time. I'm trying to not let this steal my joy. My temporary solution is to drive in Sport Suspension mode all of the time so that the stiffer setting and bumps in the road mask the shudder at bit. I guess I'm going to try and avoid 2,000-4,000 RPMs as much as possible. I don't think I'm going to last long with this one. I may beg the dealer to buy the car despite them not thinking there is a problem and eat the $30K.

My hands are thrown up in the air is disappointment...

I'm not sure what I'm going to do. I could easily put the factory exhaust back on and drop the car off. I just don't think they are going to do anything.

 

I decided to just ignore it. It's clearly something they can't acknowledge, let alone fix. If I get too annoyed about it, it will just destroy the enjoyment I otherwise get from the car.

 

Bummer. I have a few thoughts:

- before giving up, take off the exhaust and give them a chance to fix it.
- talk to the sales guy and see what they'll do for you.
- trade it on the M3 whenever it gets here. At least you'll save the sales tax.

If they don't perceive a problem, then it's likely that the used car manager won't either. Those guys never drive anything easy; he'll jump in and hammer it, enjoy that loud exhaust and then offer you wholesale.

Best of luck!

 

Here is what I would do.
Leave the car exactly as is and take it to a reputable tuner.
It has NOTHING to do with your exhaust and we all knew that Porsche along with their minions would (predictably) throw the aftermarket exhaust on the table as a possible culprit.

My car is 100% stock. Perhaps my toll pass is causing the stumble!

Just as Nick Murray's smoking, leaking, stalling car was apparently blamed on his radar detector, the Technical Service bulletin for a damaged wiring harness for his model year was never acknowledged / mentioned.

You have nothing to lose with a tune.
30k is a lot of money (by my meager standards) and driving more aggressively is not an option. I certainly don't intend to do 40 mph in 1st gear in my neighborhood in order to avoid the stumble.

A tuner will at least be willing to address your problem.

That is my next course of action.

Or, call your regional PCNA rep.

 

I think it's a waste of time dealing with the dealer. I'd keep your exhaust on. Anytime you bring up anything related to the internet they act like you're trying to convince them that aliens exist! I'd start doing some research and reaching out to independent guys that work specifically on Porsche. Did Champion ever get back to you? I'm sure this issue has to be familiar with the guys that actually know what they're talking about. Don't give up on your great 991 so easy.

The Porsche dealers don't have a clue unless their computer pops up an error message. They couldn't trouble shoot low tire pressure if they didn't have a sensor to tell them the tire looked flat!

 

Sorry to hear things didn't go as planned. The bottom line is that maybe we have to learn to live with the stumble. It's tough though, as you know, because once you experience it you're continually aware of it from then on. I'm so used to it by now that on the rare occasion when it doesn't stumble it perks my attention.

The sad truth is that the hesitation/stumble is real on some cars, although it varies in intensity. I'm still amazed that it won't trigger a code. (Of course, Porsche has probably programmed the OBC to accept the stumble as normal operation).

 

I will say it again - The fact that this problem does not occur in all 991s and seems to be somewhat random would suggest that it's NOT normal and a fix to replicate the non-stumbling cars is out there.

For those who are not sure if they have the stumble, trust me when I tell you that you'd know if you had it. It's not something that you have to look for.

 

Perhaps a forum poll might be in order?

 

I just got off the phone with Tom @ Champion. He said he wasn't aware of the problem we are having. I asked him his opinion on getting a GIAC flash tune. Natureally he said if it was his car, he would want to diagnose the problem before creating another one by tuning the car.

A possible test can be to pay a GIAC dealer for their time, get the car flashed, drive it for a few days, and then have the flash removed. I don't think the record of the tune will be wiped clean. But it could at least test to see if aftermarket software will fix it.

 

Sorry you did not have a good visit with the dealer, but I can't say I'm surprised. They have no incentive to chase down something when they can just declare it normal and tell there are no codes. That means less work for them and they can move on to more overpriced oil changes.

 

All,

Austin from GIAC was kind enough to provide me his thoughts on a GIAC flash tune improving the problem.


I Wrote:
I talked to Tom @ Champion. He suggested I contact you to inquire about a DME flash on a Powerkit equipped car. Is there a flash available that is specific to the Powerkit cars?

The main reason for my inquiry is that 991 911s are having an undiagnosed hesitation/stumble from 2,500-4,000 under light to moderate acceleration. There are a few dozen of us on Rennlist and 6speedonline getting together to try and figure this out. My hope is that your flash tune could fix the problem. Most speculate it is an issue with the VarioCam system. My car ran perfectly fine until I reached about 4,000 miles. Now it feels much like a misfire at the aforementioned RPM range. Have you encountered any cars with this issue? Do you believe your flash could help?

Austin Replied:
"Hello Matt,

I have been following the thread on 6speed online. Of all of the 991S models I have ever driven, I've yet to experience that. Though, I've only driven one stock (Supreme Power's PDK 991S). If this were an inherent issue that present when the vehicle was new, it is possible that software could fix it. I am not confident that the issue could be software if it arose after about 4,000 miles. That type of timing would point to there being some kind of faulty hardware somewhere that is failing after a number of miles. That said, I have yet to hear of this issue on any of the cars that we have flashed.

Regarding our software and the X51 power kit, our software is compatible with them and we have done them with good results."