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Yup -- You get exactly the same error I do, under the same conditions.
If we found some really capable firmware coder, we could eliminate the test, BUT the test is there for a reason. We fail it because changing the 997 MC defeats the PSM. If the PSM system can't build pressure when the brake is not applied, then it can't do its job.
So, we're left with lots of less than ideal options... Ultimately, we really need a braking guru to help us figure out how to build/modify a MC that is PSM compatible with a larger 27mm piston. Hell, while they are at it, they could correct the 996TT excessive front brake bias!
Are there any entrepreneurial brake experts out there? There is a market need... I bet you'd sell hundreds, if not thousands, of such a master cylinder. That might sound like hyperbole, but the potential market is huge... Think of the numbers of Bosch 5.7 cars (Porsche 996, BMW M3/M5, Audi S/RS) that would benefit -- I'll bet it is 100,000+ vehicles. Heck, the 996TT is 30,000 units alone. Breakeven/payback volume should be easy to achieve.
I had no error messages on my 2003 Carrera 2 with PSM when using this master cylinder. None at all. Searching here the problem seems to be with Turbo cars. The PSM pump location is different on Turbos...it's right under the master cylinder. On my C2 the pump was over on the passenger's side of the frunk. Not sure if the system is different or just the location of the pump but that could indicate some sort of difference in the two systems.
very very interesting !
in my case, i had this error, ..not with a turbo, ..but with a 986 (Boxster S). this is a 2001, with the psm pump on the passenger side.
(note : i do have a big brake kit on the front, i.e.: large rotors with 6 piston calipers)
I have just finished this 27mm brake master cylinder mod on my 2002 C4 with PSM. The PSM/ABS error trips once the car passes 50kph/30mph with the 4460 code.
Following suggestions found on the internet, I unplugged the PSM pump connector (by the pump itself), the PSM error lights up along with the error message when the car is started (the message reappears after about 30mins), but the ABS functions like normal.
I've been thinking about this situation, would there be a way to tap into the sensor output wire to alter the voltage, so the ECU will see a correct voltage signal when it does the check?
I know this wouldn't be the best way to do it as the ECU would then by fooled, but at least for those of us who don't track our cars, it can pass MOT without having to reinstall the stock MC and bleed the whole system.
For those who have been having a hard time finding this master cylinder, if you check the part number 997-355-910-30 in the 997-1 parts catalog, you will find that the C4, C4S and Targa S share the same part number. I purchased the 997C4S item, which looks exactly the same as the 997GT3 one (with the two round milled out circles). The braking effect is the same as everyone has described, so I think the one I purchased is shared with the 997GT3.
@GVA-SFO,
Ultimately, we really need a braking guru to help us figure out how to build/modify a MC that is PSM compatible with a larger 27mm piston.
John
Yes, I think this should be our mutual goal.
Keep us up to date about your tentative of message to TRW !
Portless designs relieve pressure through a check valve in the plunger rather than directly to the reservoir. This is a more complex design, which explains why the OEM MC is more expensive than the conventional 997 designs.
Someone posted this on the GT3 forum...if you have a Non-PSM car you can buy the Boxster line that goes from the rear M/C port to the ABS unit and avoid needing to use an adapter. The Boxster line is the same as the 996 Non-PSM line but is M12 for the rear port instead of M10 so it eliminates the need for an adapter. Does not work for PSM (Please Save Me - LOL-) cars.
The part number for this line is 996 355 313 04. I ordered one and installed on my non-PSM GT3 without any issues.
Hello Nickshu,
I have tried to install the bigger MC in my C2 but no luck. May I ask whether your C2 have PSM or not? I'm wondering whether the PSM might affect the fault code.
Seems like a lot of fun to try, but I wonder if the return on the time and effort expended is worth it for a DD or occasional HPDE car with the right upkeep, pads and fluid.
Hi, I have a 2004 C2 40Jahre version with PSM fitted, and just got the PMN166 from mail order today. Will it fit without any errorcodes? Any idea/experience?
Hi, I have a 2004 C2 40Jahre version with PSM fitted, and just got the PMN166 from mail order today. Will it fit without any errorcodes? Any idea/experience?
Unlikely it will work without any codes.
As previous posts have stated, you will get ABS and PSM codes and error lights on your dash and both will be non-functional. These errors will come up as soon as you hit 50km/h (30mph), at which speed the ECU checks the pump for correct pressure. The PMN166 does not have the correct fluid routing for the PSM system, so the fluid pressure will not be correct, thus tripping the codes.
If you unplug your PSM power plug, you will not get the ABS light on your dash, and ABS will function. The PSM light and error will remain. You might also feel your brakes to drag while driving, which is very dangerous.
I have a 2002 C4 with PSM, and the PMN166/997GT3 brake master cylinder is not compatible with it. A friend of mine installed one in his C2 with PSM, it didn't work either.
11-19-2018, 09:45 PM
