Crown

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    Lurching problem?

    Sorry to mention the lurching thing again but I tried to get information about the lurching problem from my mechanic and he can't find anything. There doesn't seem to be any service bulletin mentioning the lurching "problem".
    I also asked Jochen Albig during the Leipzig event if he knows something and he said that he doesn't know anything about such a problem on the Cayenne.
    I discussed with him the "lurching" phenomenon and he actually said that this is no problem but a characteristic of the Tiptronic. If you want the Tiptronic to react very sporty, you have to drive sporty.
    Example: you approach a curve at low speed and moderate braking and after you exit the curve, you want to accelerate and find yourself one or two gears too high.
    This is normal!
    The right thing to do would be:
    approach the curve fast, brake hard, take the curve and fully accelerate again. This should work, the Tiptronic chooses a lower gear. I didn't try this myself but I'll do so as soon as I have my car.

    Now here's the question: did anybody of those who had the lurching "problem" and had a fix applied at the dealer actually see a service bulletin regarding this problem? Anything written from Porsche? Did somebody watch the dealer how he upgraded the software?
    Why I ask? Because some people who I talked to deny any fix for a problem which doesn't seem to exist.
    Now I wonder if the dealers actually did nothing and customers are just made believe that something has been done or if there really is a fix and Porsche doesn't want to make it public.

    Now what's the deal?

    Re: Lurching problem?

    Hi RC

    The phenon is drastically reduced by remapping the DME, a function of the PST2 unit. There is also a kickdown change which allows correct changedown and hold on decelleration.

    I found that after those two were done (still no TSB) the lurching effect was almost eliminated, apart from in a tight corner (90 degrees) where the transmission still only goes down to 3, if you were sticking it you would pick 2.

    The dealers here (US) found out directly from PCNA, its not in the book, there must be some sort of informal notice in advance of a TSB in use.

    Re: Lurching problem?

    Thanks Mick but did you see the info or remapping process with your OWN eyes?
    I asked so many Porsche officials and nobody seems to know anything about it.
    It might be a "problem" on US cars only but it is somehow strange that there is no written info on that.

    Re: Lurching problem?

    RC,

    I got accidentaly acquainted with someone from the "core" project team of the Cayenne a short wile ago. He wouldn't/couldn't go to deep into the details but sort of confirmed that there's a DME remapping. However, due to different noise-regulations and effect on fuel consumption, it is not available for European models.

    Re: Lurching problem?

    They pointed it out on the acreen of the PST2 but I have to admit I did not comprehend what they were showing.

    Heres what I was "told" it did and I can confirm this from use.

    The initial pedal travel on the Cayenne "drive by wire" system was not made with a smooth enough curve for "normal" driving. (which would explain why if you drive like a bandit you will never see the problem)

    With the new curve its much more proportional on the pedal i.e more movement per kph in the first part of the curve = less chance of the wife getting whiplash.

    Re: Lurching problem?

    Quote:
    Matt C said:
    RC,

    I got accidentaly acquainted with someone from the "core" project team of the Cayenne a short wile ago. He wouldn't/couldn't go to deep into the details but sort of confirmed that there's a DME remapping. However, due to different noise-regulations and effect on fuel consumption, it is not available for European models.



    Thanks Matt but there are still some factors within this story I don't quite understand. I'll have to do it the "hard way" to get a satisfactory answer, meaning: if my Cayenne Turbo shows the same problem, I'll be a pain in the a.. to certain people at PAG until it is going to be fixed.

    Re: Lurching problem?

    I am looking forward to your impressions. This issue is murky at best however I do believe there is an undocumented DME update, at least in the US, and I believe this update is coordinated by PCNA and regional service reps are providing training in the update.

    I think some dealers are also trying additional steps to assist their customers but this additional assistance is not coordinated by PCNA and varies by dealership.

    I am not sure European spec Cayennes even have this issue so, as I said, I am very interested in hearing your impressions.

    Re: Lurching problem?

    Gary, the funny part is: my sources claim there is no such fix for US Cayennes. And this is exactly what I don't understand. Even more strange: nobody in the US seem to ever have seen a service bulletin or technical info regarding this issue.
    I don't say the problem doesn't exist, I'm just curious to learn why it is kept that "secret" IF it is exists.

    Re: Lurching problem?

    Quote:
    RC said:
    Gary, the funny part is: my sources claim there is no such fix for US Cayennes. And this is exactly what I don't understand. Even more strange: nobody in the US seem to ever have seen a service bulletin or technical info regarding this issue.
    I don't say the problem doesn't exist, I'm just curious to learn why it is kept that "secret" IF it is exists.



    There is that possibility but there seems to be too much evidence otherwise. You are correct about the documentation, there is none. I have been watching the TSB's for this one to surface but, so far nothing. My dealer says PCNA is trying to keep it quite, but did not fully explain why. It may be that the DME remapping increases fuel consumption or emissions or has some other politically incorrect side effect that enthusiasts wouldn't be concerned with, but anti-SUV fanatics might. I can think of lots of reasons why Porsche might want to deny anything was happening. But, in the US, it seems that every dealer is now aware of it and is doing the remapping. I doubt that it is a ruse, but, I agree that's a possibility.

    Re: Lurching problem?

    One thing that did cross my mind was that Porsche did not expect the driving patterns typical of daily drivers in the US. As a result of complaint a local US "patch" was designed to handle the stop start traffic typical of a US commute.

    Add to that the fact that the majority are not sport car drivers, in fac they drive in a sedate manner most of the time.

    As a result of the above they set up the drive by wire to be aggressive from a standing or slow start.

    It should be an easy thing to test, Matt in Switzerland has been around his Cayenne a long time I will ask for his impressions.

    Re: Lurching problem?

    Well, after that quick PM exchange with Mick, I thought it might be a good idea to try to sum up what has been going on and written about the "lurching" on this and the "other" board.

    I believe that we - Gary, Mick, and myself - have a common understanding that there are two issues that need to be separated.

    I) the lurching - a hypersensitive gaspedal which makes your passengers spill their coffee when you drive off

    II) the hesitation to downshift - perfectly described by RC on his first post in the thread.

    While I am not sure whether I have this lurching issue on my Cayenne or my foot just has adapted to it by having its on DME "remapped", the hesitation is present and cannot be excused by "it's not a bug, it's a feature". I do agree that when the car is driven in a sporty manner, that the shifting pattern is fine. However, I still think that there's room for improvement for the "normal" driving style by having the DME downshift just a bit more aggressive. It'll be interesting to see if the Turbo (with more low-end torque) will be able to cover the fact, that the transmission is often a gear or two too high when coming out of the corner.

    Since the infamous US-DME-update is not available in Europe or at least not in Switzerland, I cannot comment on the effect it has on either of these two issues.

     
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