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Here's another one for PV997 and everybody else to weigh in. 2011 987.2 got the transmission emergency run and CEL. Pulled the codes and found the following.
I'm guessing the high temperature is due to the clutch actually slipping. Sounds to me like the issue could be either with the pressure control for clutch 2 or the clutch itself. Haven't heard much about actual clutch failures so thinking (hoping) it's on the pressure control side. The car has 85k miles but is stock and has not been tracked or abused, just daily driven. One other thing of interest is this entry from when the previous owner had it at the dealership.
This makes me suspect the Clutch 2 solenoid rather than the clutch itself (although I guess the slipping caused by a faulty solenoid may have damaged the clutch). I removed the pan and visually inspected the clutch 2 solenoid. No obvious issues and it measured 6 ohm which I believe is typical. Applying 9V causes it to "click". Not sure how to properly test this type of solenoid.
The fluid looked great when I drained it. No signs of particles on the plug or the filter.
Considering a few options:
1, Replace the Clutch 2 solenoid only
2, Replace all solenoids (Chinese vendor)
3, Replace valve body including solenoid (Chinese or OEM).
Here's another one for PV997 and everybody else to weigh in. 2011 987.2 got the transmission emergency run and CEL. Pulled the codes and found the following.
I'm guessing the high temperature is due to the clutch actually slipping. Sounds to me like the issue could be either with the pressure control for clutch 2 or the clutch itself. Haven't heard much about actual clutch failures so thinking (hoping) it's on the pressure control side. The car has 85k miles but is stock and has not been tracked or abused, just daily driven. One other thing of interest is this entry from when the previous owner had it at the dealership.
This makes me suspect the Clutch 2 solenoid rather than the clutch itself (although I guess the slipping caused by a faulty solenoid may have damaged the clutch). I removed the pan and visually inspected the clutch 2 solenoid. No obvious issues and it measured 6 ohm which I believe is typical. Applying 9V causes it to "click". Not sure how to properly test this type of solenoid.
The fluid looked great when I drained it. No signs of particles on the plug or the filter.
Considering a few options:
1, Replace the Clutch 2 solenoid only
2, Replace all solenoids (Chinese vendor)
3, Replace valve body including solenoid (Chinese or OEM).
Words of wisdom appreciated...
Hey stjoh - Good to hear from you again. I think you are right in that the clutch is slippling, that ratio mismatch fault means the engine speed sensor and the PDK speed sensor (after the clutch) don't match. Hopefully it's not the clutch itself but finding clean fluid is a good sign. That dealership work order is weird, but probably just means the plastic cover came off the solenoid. I don't know how the solenoid itself could move with that retaining bracket.
Well, I like to start with the most likely *cheapest* solution so my comments below are influenced by that.
I'd probably just replace the solenoid since you can get a brand new ZF unit for pretty cheap and the Chinese set is remanufactured (not sure exactly what that do in that process). The clutch 2 solenoid is readily available unlike the the special clutch 1 solenoid. Once it's back together you can stripchart clutch 1 and clutch 2 pressures with your PIWIS and compare the two. BTW, sometimes solenoids just get stuck or clogged up with sediment and you can flush them with a solvent while actuating them and get them working again.
There's also a valve inside the valve body directly after the solenoid, you can see it in the cutaway drawing of the valve body in the main post. These move back and forth with the fluid pressure and can also fail (usually a seal). I've never seen a rebuild kit for the PDK but Sonnax makes them for a bunch of ZF transmissions and it wouldn't surprise me if they reused the springs and seals from other ZFs. Worst case you can replace the whole valve body but that's a pretty expensive way to find out the clutch is actually bad.
Hey stjoh - Good to hear from you again. I think you are right in that the clutch is slippling, that ratio mismatch fault means the engine speed sensor and the PDK speed sensor (after the clutch) don't match. Hopefully it's not the clutch itself but finding clean fluid is a good sign. That dealership work order is weird, but probably just means the plastic cover came off the solenoid. I don't know how the solenoid itself could move with that retaining bracket.
Well, I like to start with the most likely *cheapest* solution so my comments below are influenced by that.
I'd probably just replace the solenoid since you can get a brand new ZF unit for pretty cheap and the Chinese set is remanufactured (not sure exactly what that do in that process). The clutch 2 solenoid is readily available unlike the the special clutch 1 solenoid. Once it's back together you can stripchart clutch 1 and clutch 2 pressures with your PIWIS and compare the two. BTW, sometimes solenoids just get stuck or clogged up with sediment and you can flush them with a solvent while actuating them and get them working again.
There's also a valve inside the valve body directly after the solenoid, you can see it in the cutaway drawing of the valve body in the main post. These move back and forth with the fluid pressure and can also fail (usually a seal). I've never seen a rebuild kit for the PDK but Sonnax makes them for a bunch of ZF transmissions and it wouldn't surprise me if they reused the springs and seals from other ZFs. Worst case you can replace the whole valve body but that's a pretty expensive way to find out the clutch is actually bad.
Let us know how it goes and good luck.
I agree that the repair was just related to the plastic cover. Just a bit concerned that the epoxi may have come off and found it's way into the valve body / solenoids. Pretty harsh environment.
I ordered a replacement Clutch 2 solenoid. Like you said, may as well try the easiest first. If that doesn't work I think I'll just go for replacing the whole valve body next. WIll report back when installed and calibrated.
So all said I am amazed with this info. Thank you. From a diagnosis standpoint, if downshifting above 2250 rpm I hear a clunking noise in 3rd & 2nd, but not the other gears. Would that likely be a solenoid EDS issue or an alignment issue or?
OR, should I replace the transmission! Haha
Considering a few options:
1, Replace the Clutch 2 solenoid only
2, Replace all solenoids (Chinese vendor)
3, Replace valve body including solenoid (Chinese or OEM).
Words of wisdom appreciated...
This can also very well be yellow speed sensor went bad. Gives a bad reading -> TCU thinks that the gearbox speed is different from input speed -> therefore clutch sleeps... when in reality it's just bad data from gb speed sensor, and clutch is fine.
So all said I am amazed with this info. Thank you. From a diagnosis standpoint, if downshifting above 2250 rpm I hear a clunking noise in 3rd & 2nd, but not the other gears. Would that likely be a solenoid EDS issue or an alignment issue or?
OR, should I replace the transmission! Haha
Hi Jason - There isn't anything I can think of that would *only* cause the noise when going from 3rd to 2nd without showing up at other shift points. If it was a clutch solenoid I would also expect it from 5th to 4th (since one clutch solenoid does odd gears, one even gears). The shift rods solenoids also have their own pattern (as described in the post) which I would think would cause the noise at other shift points. The key to this is figuring out the pattern and common cause which is why I spend so much time in the post explaining *how* things work.
T-Design brings up a good point that if the speed sensor was providing flaky data, the shifting issue could be in response to it. Unless the speed sensor outright fails, the ECU may think bad data is real and it's adjusting clutch action in response. Flaky data from the pressure sensors could cause the same thing. If you have access to a PIWIS you can strip chart these sensors while driving and see if anomalous sensor behavior correlates with the clunking.
If you are feeling lucky you could just throw a Chinese remanufactured solenoid kit at it and hope for the best. Part and fluid would run about $300 if you DIY. You will likely need to calibrate the PDK afterwards so you'll need a PIWIS or a trip to the dealership.
Hello PV997 - first off - thank you for what you have done here. I am new to the forum, but not Porsche. I am looking for my first water-cooled 911. I admit I was put off from PDK before your posts. At the start of your investigation the original eye-watering $20K price tag for PDK replacement was a deal-breaker for me.
You, along with the others here have changed that in to a much more manageable number, So thank you to you and the collective here for your work. Amazing knowledge base.
I wanted to share this pic from a Porsche dealer website. I think this is a 992 8 speed PDK- hoping some experts can chime in. Hard to tell from just one picture, but it looks like they have modified the design. I don't see the same distance sensor set up. Hoping for all future owners it will become a serviceable part, like the Panamera. Mind you, the $1200+ price tag for the Panamera part is a joke. Audi has a similar problem, and the part is "only" $300
Hey guys, I’m new here (from Belgium), but really impressed with the info I find here, super detailed and high quality description of the PDK (awesome job PV997 ).
Hope you guys can help me with a weird problem (PDK related, I think).
The problem car is my 2009 997.2 4S.
It all started with (sometimes) overshooting rpm (300/500rpm) when shifting.
Then a had fluctuations in rpm between 1700 and 2000 rpm (in man/auto/sport/sport+ and cruise-control, also in all gears).
At about the same period I had a little slip from the clutch always between the 1700 and 2000rpm (all gears).
Al under 1700 and al above 2000rpm the car is driving perfectly.
Clutch slip is always when smooth acceleration.
Hard acceleration give minor slip between 1700 and 2000rpm and totally now slip, with start hard acceleration above 2000rpm…weird (so I think the clutch is ok?)
I already have the MAF sensor and E-gas replaced (fluctuation rpm) --> no luck.
Then i have the hydraulic oil (+ filter) changed (at a local Porsche shop), because I don’t have piwis or anything like that. --> no luck (no error code was displayed, just one after the oil change "1802" shift key lock).
The oil and filter were relatively clean, but replaced the filter anyway, just to be shore (was 60k km in the car).
The slipping is also worse when the engine is up to temp.
After reading this sticky I lean more towards looking for the problem at the valve-body and/of solenoids (maybe clutch pressure is to low between 1700-2000 rpm, reason.... ?!)
I love to hear the opinion from you guys. Can’t find anything on the internet with the same symptoms, a real brain teaser
Thx in advance and hope the English is not to bad (I’m from Belgium )
What year is your 991? I have the 997/987 PDK code reference and neither of those two codes are listed. There are other codes in the P176x family (engagement/disengagement block) that generally mean the TCU has locked out gear selection in response to something like a hydraulic fault, so that is consistent.
First thing I'd check is that the clutch fluid is at the proper level and/or there is nothing wrong with it (i.e. burned smell or appearance). Assuming that's okay, the next likely culprit is the valve body as you suspect. Resistance of 6 Ohms is good but that simply means there is no open or short in the solenoid. One can still get stuck and read the proper resistance. Additionally, one of the moving valves within the valve body could be worn or broken, so even if the solenoid is working properly it's possible the pressure isn't being controlled correctly.
Next thing could be that the valve body is fine and the pressure sensor is reading incorrectly. There are two of them so reading and comparing the resistance of both would be a good way to check for gross errors. Both should read about the same with the engine off (i.e. no pressure). You can get real time measurements (and even strip chart) these using your PIWIS which would be helpful.
Worst case there could be an actual mechanical failure in the clutch or shift rod control circuit that affects overall hydraulic system pressure. This is pretty unlikely but it's possible.
Without more specific info on the fault codes it's difficult to narrow it down further. If anyone has the 991 PDK fault code document that includes these two codes, please post an excerpt.
Update if you can help at all. So replaced the valve block all faults cleared. Oil that come out the box was nice and clean, now getting a error on calibration and keeps failing. have added a couple of pics if anyone can help.
Update if you can help at all. So replaced the valve block all faults cleared. Oil that come out the box was nice and clean, now getting a error on calibration and keeps failing. have added a couple of pics if anyone can help.
Are you running "calibration after part replacement" (what Porsche calls a *major* calibration)? There's both a minor calibration and major calibration and there's a lot of confusion regarding which one people are using when they report problems. We've seen that hydraulic teach-in error seen in your third photo with a "yes" (aka HYTI - P1872 fault) several times now and the Porsche T-shooting flow diagram specifically calls out perform "calibration after part replacement" as the remedy.
BTW, not sure if it's needed but Porsche also specifically says the torque loss adaptation must be run prior to PDK calibration. I don't know why and frankly it doesn't make sense to me but presumably they say it for a reason. See the third page of the first document linked at the bottom of the main post.
Please follow up here with your results so we can continue to crowd source what works and what doesn't. Good luck.
Hello PV997 - first off - thank you for what you have done here. I am new to the forum, but not Porsche. I am looking for my first water-cooled 911. I admit I was put off from PDK before your posts. At the start of your investigation the original eye-watering $20K price tag for PDK replacement was a deal-breaker for me.
You, along with the others here have changed that in to a much more manageable number, So thank you to you and the collective here for your work. Amazing knowledge base.
I wanted to share this pic from a Porsche dealer website. I think this is a 992 8 speed PDK- hoping some experts can chime in. Hard to tell from just one picture, but it looks like they have modified the design. I don't see the same distance sensor set up. Hoping for all future owners it will become a serviceable part, like the Panamera. Mind you, the $1200+ price tag for the Panamera part is a joke. Audi has a similar problem, and the part is "only" $300
Well done on all of your work here.
Thanks and nice drawing, I had not seen it as I've stuck mostly with the 7-speed PDK. You are right in that there is no obvious distance sensor but they must have one somewhere I would link. Anyone have any idea where it is? As the 991.2 and 981.2's are starting to go off warranty I suspect it's just a matter of time until they start showing up here too.
Are you running "calibration after part replacement" (what Porsche calls a *major* calibration)? There's both a minor calibration and major calibration and there's a lot of confusion regarding which one people are using when they report problems. We've seen that hydraulic teach-in error seen in your third photo with a "yes" (aka HYTI - P1872 fault) several times now and the Porsche T-shooting flow diagram specifically calls out perform "calibration after part replacement" as the remedy.
BTW, not sure if it's needed but Porsche also specifically says the torque loss adaptation must be run prior to PDK calibration. I don't know why and frankly it doesn't make sense to me but presumably they say it for a reason. See the third page of the first document linked at the bottom of the main post.
Please follow up here with your results so we can continue to crowd source what works and what doesn't. Good luck.
First I tried calibration after part replacement but it failed so then tried calibration without. Only thing I have not done is the toque loss adaption. Will give that a go tomorrow and let you know.
any one know where I could find this on the piwis ?
Hey guys, I’m new here (from Belgium), but really impressed with the info I find here, super detailed and high quality description of the PDK (awesome job PV997 ).
Hope you guys can help me with a weird problem (PDK related, I think).
The problem car is my 2009 997.2 4S.
It all started with (sometimes) overshooting rpm (300/500rpm) when shifting.
Then a had fluctuations in rpm between 1700 and 2000 rpm (in man/auto/sport/sport+ and cruise-control, also in all gears).
At about the same period I had a little slip from the clutch always between the 1700 and 2000rpm (all gears).
Al under 1700 and al above 2000rpm the car is driving perfectly.
Clutch slip is always when smooth acceleration.
Hard acceleration give minor slip between 1700 and 2000rpm and totally now slip, with start hard acceleration above 2000rpm…weird (so I think the clutch is ok?)
I already have the MAF sensor and E-gas replaced (fluctuation rpm) --> no luck.
Then i have the hydraulic oil (+ filter) changed (at a local Porsche shop), because I don’t have piwis or anything like that. --> no luck (no error code was displayed, just one after the oil change "1802" shift key lock).
The oil and filter were relatively clean, but replaced the filter anyway, just to be shore (was 60k km in the car).
The slipping is also worse when the engine is up to temp.
After reading this sticky I lean more towards looking for the problem at the valve-body and/of solenoids (maybe clutch pressure is to low between 1700-2000 rpm, reason.... ?!)
I love to hear the opinion from you guys. Can’t find anything on the internet with the same symptoms, a real brain teaser
Thx in advance and hope the English is not to bad (I’m from Belgium )
Hi boxterke - Is there a specific gear pattern where the slipping happens or does not happen? For example, does it only happen when in odd gears but not even gears? The main post section on the valve body describes how the different solenoids affect different gears, if there's a pattern it's very helpful in localizing the issue.
Aside from that, you really need access to a PIWIS so you can stripchart the various sensors and solenoid currents to figure out the cause. My guess is it could be a sticky solenoid or valve within the valve body but without more information it's hard to narrow it down.
10-10-2021, 08:24 PM
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