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Discussion Starter · #1 ·
While on the track today my PDK went into limp mode only allowing fifth and sixth gear. The message on PCM read "transm fault, poss no R, drive poss". Not having seen this before in other track days at much higher ambient temps I packed up my stuff without turning the car off and limped the 60 miles home. I was afraid to turn the car off that far from home for fear of it completely faulting. When I got home I turned the car off and then started it again and the fault was gone and all is well. Is the message I received the message for high PDK oil temp? The car is in warranty and even though all seems well should I have the dealer look at it? Is this the new computer age of autos and I should just get over it?
 

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somebody needs a third radiator!!

it should be fine.. was it a hot day? around 100 degrees or so? what was your water and oil temp?

been here with the local boys and girls..

Lemon
 

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#1 faulty sensor.
#2 faulty message to ECU.
#3 Oil was to hot and you need to read the above post by Schnell
#4 Major problem

If it continues to happpen under normal driving #1#2 maybe #4 if not #3
I would be at the service bay at 7Am sharp.Good reason to drive a loaner!
God only knows you were on I95, I75 or I4 when this happened WINK WINK ;)
 

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Discussion Starter · #5 ·
It was the end of the third session. Drove the car tonight and all is well, I guess I should have let the car cool off and shut it down. An hour later I could have run my last session.
 

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maybe every 5-8 laps do a full cooldown lap then proceed again, or...get a third radiator.
 

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run your car today a bit hard.. go outside.. see if both fans are working on each radiator..we had a local..had a faulty fan unit.. on the passenger side..

the other time.. there was a small leak caused by a hit on the radiator.. by a nail by all things.. and it was enough to loose pressure on the cooling system and heat up the system.. and then the PDK..



lemon
 

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Feel free to call the shop directly on our new phone number: (386)265-1979 or if you want to email me directly at [email protected], you can. Were you at the CHIN event at Sebring? Where were you? it was 82 degrees there this past week. Unlike the 987.2 that came standard with a center 3rd radiator, your 981 does not. Take Lemon's advice, call him and get a center 3rd radiator and then make an appointment to have us or your dealership install it. we charge 4 hours labor but your dealership isnt going to tell you how they can make Caymans run at 191 degrees on the water and 220 on the oil all summer long. We will though!

HOWEVER, it may not cure your problems in the dead of summer. This is just a band-aid that any and all 981 owners should put on because it's the best $1350ish dollars you can spend on your car. Your PDK wet clutch cooler is taxed because it lives next to your exhaust headers, wedged behind your motor and attached to your gearbox. It relies on pushing coolant through an oil cooler but it's hot under there...the center 3rd radiator helps but you need more air flow and you need to do more to try and keep fluid temps down.

Of my 987.2 customers with PDK that had the center radiator EVERY SINGLE ONE purchases our air-oil cooler for the gearbox. The center radiator won't cure it but you're leaving help on the table if you don't buy one. You need to come up here and do some preventive cooling work if you are going to be going on track more this Spring & Summer.

We don't get a huge discount on the center 3rd radiator and we don't mind your purchasing it from someone else on here that contributes to this forum so call Schnell and then call here and ask for John.
 

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I will add one other possibility. There are several 'Electric Control Actuators' (Porsche parts catalog lingo for vacuum control valve) that control many different things in the car. The computer can open and close and the vacuum usually then opens a water valve or other similar function (the flapper value in 3.4L intake plenum is controlled by one). If they get really soaked with water, the atmospheric port can fill with water and that disables the valve. Reading John's post above, I wouldn't be surprised that heat in the area could kill the actuator, too. The early 991s had a campaign to replace all of them, but they were a different design where water had a more direct access to the atmospheric port. The 981 version has a cap over the port to limit water ingress, but it can still flood. To release the vacuum, the actuator has to open the line that is controlled to atmospheric pressure. So the unit cannot be perfectly sealed.

Two of the actuators control the flow of water in the two PDK oil to water heat exchangers. There is a heat exchanger for the dual clutch oil and one for the gearbox oil. These valves cut off water flow when the engine is cold to quickly warm up the oil and open the valve to cool the oil when hot. Obviously, the water temperature affects the cooling ability of the heat exchangers and is why everyone recommends the third radiator. If a valve/actuator fails, then there are basically two positions. Open and closed. If closed, you could quickly overheat the oil (whichever one of the two) and the car could generate the warning that you saw.

This happened to me in January and the code was buried in the computer and John @ BGB read it out, but it could also be found with a Durametric cable. So the moral of this story is to plug the car into a tester and see if an actuator failure code is listed. If it is, the part is cheap, about $35. But you have to pull the top engine cover to get to them. They are on the driver's side (LHD) at the engine-transmission bell housing, under the throttle body.

I purchased the replacement actuator from an Orlando Porsche dealer. I had found an Atlanta dealer with the parts catalog on line and could have ordered it from them. The Orlando dealer parts guy quoted me $90 each. I told them of the Atlanta dealer online price, he went into the back (and I guess verified the price) and then came out from the back and matched it. After agreeing to match the price, I asked for two to have a spare, which I am sure didn't make the parts guy any happier. So knowledge is your friend.
 

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Discussion Starter · #12 ·
Thanks for the advice guys, the car is still in warranty so I am taking it to the dealer tomorrow to find what the code is. Looks like there will be a third radiator in my future. I do want to say thanks to BGB John for his thoughtful input on P9. I know a few guys from Sebring that speak highly of you.
 

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....... we charge 4 hours labor but your dealership isnt going to tell you how they can make Caymans run at 191 degrees on the water and 220 on the oil all summer long. We will though!......
John, sorry if I'm a bit thick, are you suggesting another resolution beyond the 3rd radiator? Like a bigger oil cooler?
My oil temps at COTA last Sunday were up to 275 on an 85 degree day.
 

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Discussion Starter · #14 ·
I took the car to the dealer who cleared the code and then reported it to Germany and to their local Porsche technical resource. The consensus is that this is a one time code which was arrived at by looking at all of the data collected. It was not high temp due to track use. My dealer service manager doesn't seem so sure but told me to drive it without restrictions and make sure to bring it in if any transmission code shows up.
 
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