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Many thanks PV997 for doing this! Great work , it's very much appreciated.
Originally Posted by PV997
Thanks mchrono. I think we may be able to find a mil-spec part or a replacement with an extended temperature range, there do seem to be some available. The distance sensor signal is so simple we don't necessarily have to have the exact same part. It is a pretty dumb device, it simply outputs four PWM signals when powered, there's no handshaking or any other complex communication. BTW, the ICs I've found that match the distance sensor output are only about $2 each.
Decided to take some measurements on the distance sensor output to help figure out the internal components. I did this by accessing the TCU (a real PITA as Mr. Hobbiest noted above) and measuring the signal with an oscilloscope. Against my better judgement I pierced the distance sensor wires with a pin so I could connect the o-scope while still keeping the circuit intact.
As expected, the output signal was pulse width modulation (PWM) with a level from around 0 to 5 volts. For those who aren't familiar with PWM it's a square wave where the width of the pulse encodes the information (i.e. the shift rod location). The period from one pulse to the next stays constant whereas the time length of the pulse (the duty factor) varies depending upon the information being transmitted. PWM is used as it's largely immune to noise unlike a simple analog signal.
Here's a plot showing a typical Hall-effect sensor PWM scheme. The short duty factor on the left corresponds to one travel extreme, the long duty factor on the right corresponds to the other extreme.
The PWM signal starts immediately once the ignition key is switched to on, there is no initialization sequence or two-way communication. The carrier frequency of the PWM signal was 1 kHz (I actually measured 1.05 kHz but there may have been some error) and the duty factor ranges from around 10% to 90% depending upon the shift rod location. Pretty much a plain vanilla signaling scheme.
I've been researching Hall-effect sensor ICs with PWM and found a couple that match these specs and were available back when the PDK was introduced. The most likely candidate is a programmable chip so we'll have to figure out a few parameters ZF used to match them. Programming is pretty simple but it does complicate things. More to come as it's figured out.
That is awesome info! Would be ideal if we could find a direct replacement with the correct switching frequency and everything. This doesn't hit all the specs you tested but something like one of these: https://www.ti.com/lit/ds/symlink/dr...oogle.com%252F
That is awesome info! Would be ideal if we could find a direct replacement with the correct switching frequency and everything. This doesn't hit all the specs you tested but something like one of these: https://www.ti.com/lit/ds/symlink/dr...oogle.com%252F
Yup, that's exactly the one I was hoping it was except it's carrier frequency is 2 kHz (not adjustable) when I measured 1 kHz. There are others from Microntas and Allegro where the carrier freq can be set to 1 kHz so I have a feeling it might be one of those. Unlike the TI chip, they need to be programmed for a few parameters (carrier freq, sense range, temp comp, etc.) which is a simple procedure but we'll have to figure out the right settings.
Yup, that's exactly the one I was hoping it was except it's carrier frequency is 2 kHz (not adjustable) when I measured 1 kHz. There are others from Microntas and Allegro where the carrier freq can be set to 1 kHz so I have a feeling it might be one of those. Unlike the TI chip, they need to be programmed for a few parameters (carrier freq, sense range, temp comp, etc.) which is a simple procedure but we'll have to figure out the right settings.
Upon first look, this one might be better, it looks really configurable to get exactly what we want and is programmable with an application kit from micronas.
I can't find a price on the USB programming kit, Ill have to reach out to one of the sales reps. Wonder what it costs.
Micronas is a German company and supplies a lot of automotive applications so who knows, they might make the exact one ZF uses in the PDK! Or ZF might even use an off the shelf version that isn't custom... that would be nice.
Now I want to open up this distance sensor even more to see if I can read any part numbers from whats actually in there.
Upon first look, this one might be better, it looks really configurable to get exactly what we want and is programmable with an application kit from micronas.
I can't find a price on the USB programming kit, Ill have to reach out to one of the sales reps. Wonder what it costs.
Micronas is a German company and supplies a lot of automotive applications so who knows, they might make the exact one ZF uses in the PDK! Or ZF might even use an off the shelf version that isn't custom... that would be nice.
Now I want to open up this distance sensor even more to see if I can read any part numbers from whats actually in there.
Thanks for pulling all this together, I'm leaning toward Micronas also due to the German connection. The USB programmer is only $125 so that shouldn't be a problem. I'd be happy to program hundreds of the ICs and send them to whoever needs them to rebuild the sensor. The part you flagged looks good but the earliest date on the datasheet is 2014 so it's probably not the exact same part in the distance sensor (though it may be fine as a replacement). Some of the other Micronas parts date from the mid-2000's and could be the exact part.
Thanks for pulling all this together, I'm leaning toward Micronas also due to the German connection. The USB programmer is only $125 so that shouldn't be a problem. I'd be happy to program hundreds of the ICs and send them to whoever needs them to rebuild the sensor. The part you flagged looks good but the earliest date on the datasheet is 2014 so it's probably not the exact same part in the distance sensor (though it may be fine as a replacement). Some of the other Micronas parts date from the mid-2000's and could be the exact part.
yeah I might buy the $159 dev kit with the usb programmer a few of the sensors and the breadboard.
the 3D hall sensors seem cool (for other projects) because you can get 3 axis magnetic field info for angle etc
...I spoke to a Porsche contact he suggested that PDK failure rate on 911/Cayman is around 6% in first 100k miles and 27% by 200k miles.
Originally Posted by 997ajk
Just to clarify the 6% was based on 997 and 987 cars (09-12) in Canada. Total sales figure was something around 3680 cars for period of 4 years, 220 replacements.
With 17 dealers in Canada at the time, it works out to 3 replacements per year per location. Hardly noticeable.
EDIT (Sep 4th): Added a clarification that costs are in $USD...
Very, very interesting.
Assuming the veracity of your contact, I was wondering about self-insure vs. aftermarket warranty (the bit covering the transmission).
Applying some classic 'man-math' ("justifying an otherwise irrational decision through application of flawed logic, logical fallacies, and liberal use of arithmetical gymnastics"), I got...
There's a number of reports here on the forum of replacing the PDK for about $14K. But I've also heard a few more recent reports that PCNA maybe charging more for replacement units. Hence the $20K assumption in the above.
But as I said, 'man-math'...
Karl.
PS: For comparison, people with 6MT transmissions seem to be averaging clutch jobs at around the 65-70K mile mark (YMMV of course), at an average cost of about $3.5K based on: https://rennlist.com/forums/997-foru...l#post16885041
Assuming the veracity of your contact, I was wondering about self-insure vs. aftermarket warranty (the bit covering the transmission).
Applying some classic 'man-math' ("justifying an otherwise irrational decision through application of flawed logic, logical fallacies, and liberal use of arithmetical gymnastics"), I got...
There's a number of reports here on the forum of replacing the PDK for about $14K. But I've also heard a few more recent reports that PCNA maybe charging more for replacement units. Hence the $20K assumption in the above.
But as I said, 'man-math'...
Karl.
PS: For comparison, people with 6MT transmissions seem to be averaging clutch jobs at around the 65-70K mile mark (YMMV of course), at an average cost of about $3.5K based on: https://rennlist.com/forums/997-foru...l#post16885041
That is a decent point about average cost exposure. However with the price so high and relatively infrequent its like hitting the reverse lottery lol.
Also I had thought about clutch replacement on MT cars, however I have been driving manuals for a long time and put a lot of miles on them and have only had to replace one clutch (and that wasn't from wear it was just because I doubled the power and the stock clutch wouldn't hold anymore lol).
I have an S2000 with almost 200k miles on the original clutch and it shows no sign of dying anytime soon, and Im not gentle with that car. It sees 9k rpm every time I drive it.
It is all in how people drive if they will need clutch replacement.
Can't share or show much else as I don't own the data this was told to me.
I wonder if Canadian climate played a larger role in the failures over the warmer states. We know from bore scoring in cold countries (Canada) is more prevalent. (This was brought up by FSI / LN )
Additionally if you search carparts.com (used parts), there are very few PDKs available and when they come up they are gone fast, but you see plenty of M/Ts - do the search for 991 and 981 PDKs and you find few all the time. That too me indicates that 997/987s are being used up as replacement, where as 991/981 are still under warranty or do not exhibit the same issue.
I wonder if we could make 991 tranny work in 997, I sourced few from Europe for $2500 shipped - I know PV997 mentioned some differences in valve bodies and secondary cooler but there has to be a way.
Just to clarify the 6% was based on 997 and 987 cars (09-12) in Canada. Total sales figure was something around 3680 cars for period of 4 years, 220 replacements.
With 17 dealers in Canada at the time, it works out to 3 replacements per year per location. Hardly noticeable.
I think these numbers are highly inflated and not even remotely accurate. I know for AFCT, not hearsay to get people worked up on internet lore like this 6% crap, that 2 dealers serving large market and 1 dealer serving a small market have seen ZERO, like NON, NADA, NEVER, NOT ONCE ever had to replace f ailed pdk in the last 3 to 5 years.
So you guys can keep spinning up drama numbers if it makes you feel well or supports your agenda, but I think its pretty sad/pathetic.
Add to that, very few Porsche contacts would have that information and non at the dealer level would have it. Hopefully, so me readers are enough to weed out the internet BS, but sadly this is the internet and a lot of bored sad people make shyte up.
I think these numbers are highly inflated and not even remotely accurate. I know for AFCT, not hearsay to get people worked up on internet lore like this 6% crap, that 2 dealers serving large market and 1 dealer serving a small market have seen ZERO, like NON, NADA, NEVER, NOT ONCE ever had to replace f ailed pdk in the last 3 to 5 years.
So you guys can keep spinning up drama numbers if it makes you feel well or supports your agenda, but I think its pretty sad/pathetic.
so will the 2 dealers you know sell parts for a PDK rather than say its non repairable and charge people a premium?
I think these numbers are highly inflated and not even remotely accurate. I know for AFCT, not hearsay to get people worked up on internet lore like this 6% crap, that 2 dealers serving large market and 1 dealer serving a small market have seen ZERO, like NON, NADA, NEVER, NOT ONCE ever had to replace f ailed pdk in the last 3 to 5 years.
So you guys can keep spinning up drama numbers if it makes you feel well or supports your agenda, but I think its pretty sad/pathetic.
I think these numbers are highly inflated and not even remotely accurate. I know for AFCT, not hearsay to get people worked up on internet lore like this 6% crap, that 2 dealers serving large market and 1 dealer serving a small market have seen ZERO, like NON, NADA, NEVER, NOT ONCE ever had to replace f ailed pdk in the last 3 to 5 years.
So you guys can keep spinning up drama numbers if it makes you feel well or supports your agenda, but I think its pretty sad/pathetic.
You sound like a sad lonely pathetic person to react like this to a thread trying to help people with expensive PDK failure.
A lot of us thought the 6% number was high and no one is saying it is a "AFCT" lol.
At the end of the day, this thread is very valuable and should help a lot of consumers fix their own transmission rather than dump $20k at a dealer, no matter what the failure rate is.
There are clearly failures, the numbers are much higher than your claimed ZERO so either way its helping a non zero amount of people.
Get your panties out of a bunch and either go away or contribute. SAD!
I've only seen one other UOA on PDK gear oil and it also showed low viscosity like your report does. I'm starting to think the 12 year/120,000 mile interval is too long as high heat quickly reduces the service life. I suspect the 987/997 gear oil ran hotter than Porsche and ZF expected, not sure why but maybe heating from the adjacent clutch fluid. I don't see how more frequent changes could help the sensors but definitely the bearings and syncros.
Keeping our fingers crossed and let us know how it goes.
Longer trip this past weekend. Data logging the entire way. NO CODES, frustratingly enough no problems during the 2+ hours of road time. Guess it's time to go back to the track. I'll keep everyone posted as to what happens next. Thanks for continuing the good work on the thread.
08-31-2020, 08:54 AM
