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Thread: PDK Sports Plus Shortshifting

  1. #21
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    I am starting to conclude this is a temperature issue. I met someone else that had this issue, and was told the first level of high (oil) temp is short shifting. He then got the oil temp as high as 300 and saw an alert pop up on his dashboard to back down. He said third radiator solved the issue.

    I tried various “home remedies” and took the car out again. This included brake flush (since the dealer thought it had something to do with brake fluid temp), running Techron in my gas, and having my radiators cleaned out. None of this worked. I then started looking at what my oil temp on the dash was immediately after this occurred. It appears as if this first stage limp mode kicked in when oil temps hit 280+. It didn’t seem to go away until it fell below a certain threshold (might have been sub 260 or so). One way to get the car going again is just to drive the car at lower revs for a bit, then get back on it. Also, cool down laps are now being done at about 4K rpm and leaving car running when I get to paddock until oil temps hit sub250. Apparently 981 engines run a lot hotter than 987’s.

    Ordering a third radiator soon and will test out in two weeks and report back.
    Last edited by wwlee; 07-22-2019 at 12:16 AM.

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  3. #22
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    Re: PDK Sports Plus Shortshifting

    If you are seeing oil temps at 280+ when it's happening, I would say it's probably temperature related. I was under the impression you were seeing it with normal oil temps.
    2014 Boxster S - Racing Yellow, Sport Chrono, PASM, PTV, PDK, 3rd radiator, Cobb Stage 1 tune (Pagid RSL29's & Nitto NT-01's on the track)

  4. #23
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    Re: PDK Sports Plus Shortshifting

    Quote Originally Posted by wwlee View Post
    This is a cross post from Rennlist...and sounds similar to an issue that Jerseydevil posted (though he was running a manual w/ RE71's)

    I have a 2014 (981) Cayman S that I track fairly frequently. It has about 40k miles – recently changed air filter and PDK flush*, along with oil changes every 3-5k miles and brake fluid changes, and already had spark plugs changed. Using Mobil 1 0-w40*. Using Pzero tires and always use PSM. Issue only appeared recently.

    On the last two sessions of a recent 3-day track event (high 80’s and sunny), I was driving the car in sports plus and allowing the car to do the shifting. Half way into the second to last half hour session, it felt as if the car went into sort of a limp mode. No fault codes/CEL, but car wouldn’t rev to redline before shifts – was short maybe 500 – 1000 RPM before shifting. I ended the session early, let the car rest, and then went back out the last session, and after 5-10 minutes laps, it “limping” again.

    I was advised by someone to do a PDK/transmission flush*, which I did along with an oil change, and brought it out to the track the following week for a test (fresh PDK/transmision fluid and oil). Temps were about high-80’s / 90 degrees – on the first day, I was able to drive 3 sessions without issue, then every session afterwards, started “limping” after 10 minutes or so – when I noticed this, I did a cool down lap and pitted in. The next day, it started “limping” after 10 minutes of the first session. Called it quits and went home.

    Brought the car to a Porsche dealer the next day – and they concluded that it was because I overheated my brake fluid (likely because that’s the only code they saw).

    A few questions come to mind:

    -I question the conclusion the dealer came up with, since I use RBF600 fluid, which was flushed beginning of the year, and bled prior to the 3-day event when the “limping” started to occur. Also, seems far fetched associating these two together…and even if I upgrade to SRF, wouldn’t the fluid still get just as hot, but not necessarily boil - setting off the high temp brake fluid sensor?

    -Someone suggested it might be a cooling fan or thermostat/sensor issue, but dealer didn’t (or couldn’t) see that.

    -I spoke to a very knowledgeable Cayman guru who said to get a third radiator, use Driven DI-40 oil and PDK cooler. I would have done this, had I not found out that there are other 981 Cayman S owners in the area that drive their cars harder/faster than me (at the same event), and do not have these modifications. My concern is that these modifications cost real money, and I cannot test if this would be successful unless I invest additional time and money into a track event to test it out (I can't replicate this problem safely on public roads)

    -I understand alot of people don't like Mobil 1, but I've always used it in the past with no issue (and know others that are faster than me using it), and used fresh Mobil 1 oil on the test event to no benefit. I have also tracked the car in 90+ weather many times in the past with no issue.

    CPO warranty is running out soon, and I’m getting frustrated throwing money and time into troubleshooting and testing the car. Was curious if anyone else had this same issue and what resolved it. Very close to selling my car and moving on in life to another hobby.

    Thanks everyone!
    Look at my earlier post. I had the exact same problem. It is my theory that the PDK will overheat in auto mode, because it does a lot of unnecessary shifts. Once I got out of auto and shifted for myself the problem disappeared. Also, shifting for yourself gets you back into the action. You should be thinking about the best places to shift rather than have the PDK do it for you. The dealer was not very helpful in solving the problem and would just insist that the PDK was operating normally. I wonder if overheating the PDK generates an error code. I don't think so.

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    Ledbette - I was looking at water temp when this first occurred and realized 194 is bogus. Then I looked at oil temp at end of a session which was anywhere from 260-270. It was when I looked at it the second it happened, I realized the trigger was 280+

    Dannov - I tried shifting myself and had the same issue. I actually met a guy in a manual 981 boxster (he had a similar post here) - the car limited his revs at each gear. My guess is that when you shifted yourself, you didn’t bring the engine to redline each time, which gets temps really hot. With PDK shortshifting that 500 rpm early, oil temps stay in range of 270-280. On my experience, keeping car in 4-5k bring temps down low enough to disengage the soft limp mode

    As far as fault code and dealer goes, I guess dealers only look at an issue (under warranty) if there’s a fault code, otherwise they’d be chasing after a problem which could be timely and expensive. And I learned that this “limp” mode is just the first stage when temps get hot. I met a guy where oil temp hit 300, and his car really went into limp mode, and saw a fault code on his car. Makes me feel a bit more comfortable driving the car in PDK auto - it’s protecting itself

    Third radiator getting installed today and will test out the car next week in close to 90 degree weather
    Last edited by wwlee; 07-30-2019 at 09:30 AM.

  7. #25
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    Re: PDK Sports Plus Shortshifting

    FYI - The PDK, even in manual, will protect itself and the engine from stalling or over-revving. I've accidentally hit the downshift paddle on a couple occasions where a shift would have over-revved the engine, so the PDK didn't shift. I've also tried to see what would happen in manual mode at low RPMs, and it will automatically downshift to keep the engine from stalling. I'm not sure at the upper-limit whether it will upshift or rev-limit you. I haven't tested that end.
    2014 Boxster S - Racing Yellow, Sport Chrono, PASM, PTV, PDK, 3rd radiator, Cobb Stage 1 tune (Pagid RSL29's & Nitto NT-01's on the track)

  8. #26
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    Quote Originally Posted by ledbette View Post
    FYI - The PDK, even in manual, will protect itself and the engine from stalling or over-revving. I've accidentally hit the downshift paddle on a couple occasions where a shift would have over-revved the engine, so the PDK didn't shift. I've also tried to see what would happen in manual mode at low RPMs, and it will automatically downshift to keep the engine from stalling. I'm not sure at the upper-limit whether it will upshift or rev-limit you. I haven't tested that end.
    Correct, PDK will not money shift as it simply wont drop into a gear that would do so.

    It will shift down on its own as you slow down in full manual mode, but will not shift up. It will simply pull fuel and bounce off the rev limiter until you shift it
    Last edited by ICNU; 07-30-2019 at 05:22 PM.

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    Re: PDK Sports Plus Shortshifting

    Quote Originally Posted by ICNU View Post
    Correct, PDK will not money shift as it simply wont drop into a gear that would do so.

    It will shift down on its own as you slow down in full manual mode, but will not shift up. It will simply pull fuel and bounce off the rev limiter until you shift it
    Interestingly enough I have some overrevs in the 1 and 2 range - probably happened when the car gets some air after a crest?

  10. #28
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    Re: PDK Sports Plus Shortshifting

    Quote Originally Posted by wwlee View Post
    Interestingly enough I have some overrevs in the 1 and 2 range - probably happened when the car gets some air after a crest?
    I'm sure I have plenty of those as well, but it should be of no consequence. You get the range 1 just for getting near the redline, and the range 2 for bouncing around on it. The official redline is 7800, and if I recall correctly the range 1 is 7500-7700 and the range 2 is 7700-7900 with the factory redline sitting right in the middle, so there could potentially be many 1-2 ranges on a car that is driven aggressively. Its when you cross over into the range 3 and above that dealers will take notice, and the PDK shouldn't allow that happen.

  11. #29
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    Re: PDK Sports Plus Shortshifting

    Just brought the car to a track event w/ the third radiator...while it wasn't quite as hot as the other events for the most part, there was maybe one session or so where my outside temperature gauge red high 90's...and only had 40 minutes between sessions. No PDK limp whatsoever, and highest I saw the oil temp go was 268. With the worst of the summer heat behind (hopefully), this car should not have pdk limp issues at least until next July.

    My previous instructor informed me that you pretty much need the car in sports+ mode at the track to get benefit of third radiator - it maximizes cooling power. On the highway, I was probably running around 225 oil temp on normal setting. When I put it to sports or sports plus (keeping revs the same), oil temperature dropped as low as 194.

    Thanks everyone for your input in this.

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