I've just completed perusing this entire thread because I have experienced fault code P2262 [boost pressure is less than set point pressure] a few times, and once a CEL with the message that driving is permitted. My 2017 C2S now has 34,500 miles on it and was given its 40k mile service by the dealership at 27k miles last year, and since then I have installed an FVD Brombacher tune after which I experienced the fault code P2262 a few times. Thus, I'm concerned that my car might be experiencing problems due to it OEM plastic diverter valves.

Many thanks to those who have contributed very much to understanding how our 3.0L twin turbo 991.2 cars engines work! And for the very helpful photos and videos depicting how various members have accessed and upgraded their diverter valves.

However, I find that I have to disagree with those who suggest or recommend installing the diverter valves such that the boost pressure is applied to keep them closed and the vacuum hose is used to open them during a lift off throttle. As some have pointed out, the replacement diverter valves have larger diaphragms or pistons on which the gases will act, thereby increasing the forces acting on the diverter valve during its functioning. I'm of the view that Porsche and others who build turbocharged engined vehicles are thinking of safety and durability of their engines and vehicles, and that includes fail-safe concepts. If the diverter valve is installed as per OEM, in the event of loss of that vacuum hose signal, the valve will still open during sudden closing of the throttle due to the action of the surge in boost pressure, thereby protecting the turbo bearings from excessive pressure surge. In contrast, if the connections are re-arranged to cause the boost pressure to hold the valve closed, and the vacuum signal is lost due to a broken vacuum hose connection, the turbo is not protected against that compressor surge upon sudden closure of the throttle valve, and turbo damage is more likely to occur.

 

@DR911s Curious to learn the outcome of your problem with the fault codes. I’m also curious because this is not the first time I’ve read about issues following the installation of the FVD tune although I’ve also read many favorable reviews.

 

I guess I’ll order a pair for the next time the rears off the car.

any experience on wether to go APR or the flat6 ones?

 

I may never be able to identify the actual problem because I don't have any way of logging performance of the car. The first time I experienced fault codes was after installation of the FVD tune, but I cleared those before driving the car. The next time was when driving on track and returning home -- no CEL but the P2262 [boost pressure doesn't match set point] upon my return home. The on-track problems may have been due to the fuel that I purchased when driving on track. The most recent event was immediately after hitting that step bump in the road which was the first time I've gotten a CEL. It hasn't returned to date nor any other fault code.

 

Here's my current status: I had another incident [3rd time] of the car "hiccuping" [on/off cyclic interruption in power which might make you think the PDK clutches are malfunctioning] upon mild to moderate acceleration at vehicle speed less than 55 MPH upon acceleration to normal 2-lane road traffic speed [limit is 55 mph] after turning from one public road to another where the second road was a slight uphill grade. That occurred after about 30 miles of driving from a cold start, and about 70 miles later, a CEL with the MFD display stating that driving was permitted. The fault codes were P0299 = Boost pressure control deviation and P2262 = Boost pressure less than setpoint value.

Also, I forwarded that information to FVD Brombacher, and received a reply less than 24 hours later from their head of IT with a revised tune file and a request for me to install it and then report back to him. I replied to him that I was first going to run my car with the OEM tune file for more miles to see if it triggered the same or any other fault codes. I'm thinking that if there's something wrong with my car such as those diverter valves or other mechanisms or control systems for the turbo boost, those should appear, and if not, then something in the FVD tune file is causing the fault codes.

To date with the OEM tune file re-installed, I've only driven my car a total of about 130 miles, with the longest individual drive being about 40 miles. I have experimented with Normal, Sport and Sport Plus modes, and thus far, no fault codes or any "hiccuping". Same tank of fuel on which the 2nd version of FVD tune file tripped the CEL and those fault codes described above.

My iCarsoft POR V3.0 was effective in finding and clearing the fault codes.

I hope to drive my car more this week and to install the version 3 from FVD.

This matter should probably be in a separate thread... . Any suggestions on how best to do that are welcome. I'm not a computer guy!

 

I would wait to see the outcome after you install the revised tune. Hopefully that solves the issue completely. After that, this might be helpful for others to know who either have this tune and experience this issue.

 

I recently reinstalled the OEM DME tune file and have been driving the car with the OEM tune for a couple of weeks, including some drives on the same roads on which I had experienced the "hiccupping" [fairly rapid off-on-off-on power delivery which at first made me think that my PDK clutch control system was malfunctioning because no CEL was occurring] during mild to moderate acceleration. I drove the car several times on local urban and suburban roads which I'm figuring allowed the car to adapt to the change in the tune file... almost 200 miles worth of cold and warm starts included. Same fuel throughout -- Meijer 93 octane which at the location I am using does not have its pumps marked to indicate added ethanol. And a few days ago, I drove the car on many of the same roads on which I had earlier experienced those glitches and more recently with the FVD Brombacher 2nd tune file installed additionally triggered the CEL. The total mileage of this last drive was nearly 200, and I intentionally selected the different drive modes for extended runs, and multiple times took the car up to 7k RPM using full throttle. No hiccups or driveline jitters were observed by myself or my passenger who is also a retired engineer. I also at times glanced at the dashboard MFT display screen on which I have Turbo Boost at the top, and saw 12 and once 14 psig. After that vigorous drive I checked for fault codes and found one in the DME: Boost pressure deviation. No CEL occurred.

I also confirm that the car with the OEM tune file is definitely less powerful than with either of the two FVD tune files I have tried. I did not attempt any measured acceleration runs to quantify the differences. Per my iCarsoft POR V3.0 scan tool, the maximum boost pressure with the OEM tune is a little over 26 psi absolute which corresponds to about 12 psig on the dash display, and that matches what I have seen while driving.

Any suggestions or recommendations to identify and correct the underlying issue? Before reinstalling the OEM tune file, I checked all the turbo hose fittings and tightened all of the hose clamps that I could reach via the wheel wells and under hood after removing the fans and shrouds as one would do to change the oil filter, and I also checked/wiggled all of the electrical connectors that I could reach. My car was given its full 4yr-30K [40k] major service in March of 2022 including spark plugs and engine air filter when it had 27k on its odometer. I recently passed 35k. No dash warnings occurred until after I installed the first FVD tune file in March or April of this year. But I didn't have a scan tool to check for any fault codes until about that same time this year, so I wouldn't know if the car was triggering any fault codes when driven hard after the major service.

I have a revised tune file which FVD quickly sent me after I informed them of the CEL and "hiccupping" behavior and the fault code P2262 pertaining to boost pressure deviation from set point value. I don't see any reason to install that file until the boost pressure deviation issue is resolved. Sensor? Leaking hose connection? Unconnected control system hose?

At this point, I'm thinking that I am "stuck" with going back the dealership who did the major service. And buying a pair of diverter valves from one of the vendors that advertise on Rennlist and having the dealership install them while they have the bumper cover off, assuming that will be necessary to correct the boost pressure deviation problem.

 

You can pressurize the intake manifold and listen for leaks. Jump to 19 min in this video to see an easy method. You can use an gage on air compressor if you don’t have a mechanical boost gage handy.

 

Thanks, MingusDew! I have watched your video and how you did the testing. Very cleverly done with shopmade "plugs" with Schrader [tire inflation] valves!

 

bump/x2, which to get?

 

I bought both, and blew out both. Switching to the TurboSmart, I know a number of guys running those with over 800whp, so they should be fine on my car.

 

Do you know exactly how they failed? I can see the APR tearing a diaphragm. The Flat 6, blow out an oring or something?

 

I have used TurboSmart, HKS and Greddy diverter valves to mid 20 psi levels of boost with no issues. Work as advertised.

 

Update for Tier1Terrier and others: I experienced the same fault codes with the OEM tune file, and after clearing the DME fault codes, installed the latest tune file from FVD, and rechecked for fault codes; none were found. Thereafter I proceeded to drive the car very easily for a couple hundred miles, and found the same P0299 fault code but no CEL. I've ordered a pair of diverter valves from Flat 6. Other than the fault code, the car starts immediately and drives normally. I'm beginning to wonder if I have had a boost leakage problem for some time because I remember thinking that my car seemed a bit down on power when driven hard on a track with which I am familiar enough to know what speeds I achieve at various natural feature markers along the long front straight, and my speeds in 2021 were higher than in 2022 after the major service by the dealer and also in 2023 for which I only needed an oil and filter change and brake fluid change which I did myself. Also, I'm typically not able to see more than 12 to 13 psig boost anywhere from 2k through 7k RPM in outside temperatures of 70 to 85 F. I'll update if I find anything when I do the install of the diverter valves and also look for any other loose hose connections.

 

@DR911s
A boost leak like that can be very hard on the turbos. Can be easy to 'overspin' them as the car tries to make target boost.

Hope you get it sorted.