I certainly understand your position. But, I never said that your software, or any one's software would cause an "engine safety" issue. I simply said that the flash would most likely cause warranty issues with PCNA on any engine warranty claims.

Are you confident enough in your statement that the flash will not cause any warranty issue, to give customers a written guarantee that your company will cover any engine related warranty claims denied by PCNA as a result of the ECU flash? Even if you offered a warranty like that, are customers really willing to possibly give up their PCNA warranty? Just because you have Porsche dealers that flash customers ECU doesn't mean that a warranty claim will not be denied by PCNA. You have to remember that it is PCNA that warrants the car, not the dealer. Are the dealers you work with willing to give a written statement/warranty to the customer that the flash will in no way impact their warranty with PCNA? Why wouldn't they if the flash has no impact on the PCNA warranty.

As I suggested earlier, any customer or vendor can contact PCNA and ask them the implications to warranty coverage from an ECU flash. I certainly support any owner doing whatever he/she wants to their car. I am just pointing out the risks involved. PCNA is getting stricter all of the time with dealers on warranty claims, and documentation required for claims. In many cases, they even require photos be taken to show no mods. Certainly an ECU flash would be easy to detect.

 

Nothing to lose if you have the stumble.

 

You seem to be implying a lot of things from my statement. Tuning vehicles is always a risk when it comes to warranty, I haven't denied that in the least. My statement was simply that it's not a cut and dry situation with warranty claims. In our experiences with Porsche, they're actually pretty fair compared some other automakers in terms of warranty claim investigation. Your statements seem to imply that if you tune your car, warranty is out the window the second you do it, which is simply untrue. We prefer to calibrate cars in a manner that will maximize reliability, that way customers never need to have that conversation with their dealer/PCNA and it's something we've done well on Porsches for nearly 20 years.

As for warranty backed items, Champion Motorsport does sell packages that offer a supplemental warranty. Is it a factory "PCNA warranty?" No, but there are plenty of people on here (in various forums) in the program that will attest to the integrity of it.

 

I just posted a question about this to the PCA national tech Q&A. Maybe I can get some discussion happening at PCA.

 

So yesterday I had another data point added to a set which warrants mention. I started noticing last Autumn that on cool dry days my car would not stumble again. Sure enough, yesterday it was 60 and dry, and the car did not really stumble. It seems like 60 degrees F is the sweet spot, and low humidity.

Just another observation to share with the group. More evidence to me that this is all about some sensor computing air/fuel mixture incorrectly. When the air temp and humidity changes, it affects the fuel mixture.

 

Is your car still stumble free? Please give us an update. The plenum would be an easy fix.
TIA

 

I don't want to get too complicated here but humor me. All NA engines are calibrated from a base point for fuel/air by the engineers. The base point reference is 59 degrees Fahrenheit, Barometric pressure @ 29.92 and measured at sea level. The scenario that you mentioned was very close at it related to temperature, however I don't know how far above sea level you were and what the Barometric pressure was. Take note of these three factors. If you find a temp close to 59 and a standard pressure day (29.92mg) and are close to mean sea level at 0 and the stumble disappears, then you are very much on to something.
You can obtain these readings from most weather reporting from airports nearby.

As to how to fix, that is above my pay grade, but it simply could be having your air/fuel mixture set on a day that is very close to standard. I am a pilot, flying NA piston engines for over 25 years. Density altitude (combo of these factors) affects power output. Throw in the mix of variable cams and it is possible that this a problem with the ECU and the baseline obtained by the sensors. Try to determine if there have been any new versions released on any an all sensors that determine F/A mixture. This could very well be why the Plenum upgrade has helped others.

 

Sorry guys but the stumbling is back after 2000kms, only less prominent. Dealer tried replacing the crank sensor, didn't work either.

 

Thanks for the feedback George - You just saved me 1000 bucks..

 

George, I think you mentioned you did the Cobb flash and you mentioned that power output was a lot smoother from it. I am assuming, based on your prior post, Cobb did not help either? Or is it too early to determine?

 

Two folks over on the other forum mentioned another recent DME flash and had their stumble go away. We all know the stumble can come back after a reset, but I'm slightly optimistic.

> Perform Campaign WF86, Reprogram DME
> FC: WF860660001
>
> No issues with mine since the reprogram.

 

Very interesting indeed!

This past Monday the 29th was the Good Car Day for me (I use that term when I have a stumble-free day, which are infrequent enough to receive a special name).

Here are the weather stats for my area for that day:
- Temperature: 60 degrees F
- Pressure: 29.89 "Hg
- Wind: 11mph

My elevation is about 380 feet above sea level.

 

Be sure to obtain several data points as above. Then obtain a few out of the parameters such as higher temp and higher Baro. Chart it and see if a pattern develops. I am betting that you will see that your car stumbles get worse with higher temps and lower pressures.

 

No, it did not help.

 

Since my 2013 C4S was do for the latest update I made an appointment for tomorrow morning to have it done. Will report back after a few trips to see if the 2-3K RPM stumble is gone.