Smithydxb

So just got round to changing both DVs as well as the MAP sensor for good measure.

unfortunately it hasn’t solved anything and I’m still losing boost, mainly from highish revs and high boost, it just drops to 0psi with the reduced power warning in yellow.

turn the car off and on again and problem resolved.

I need to locate the N75 valve to check the hoses coming off it for any leaks, if they are all fine I am completely out of ideas and assume it must be either the actual turbo actuators or something in that vicinity getting stuck or something electrical not computing something properly and unfortunately way beyond my abilities to resolve.

It will likely need to go back to Porsche for them to charge me a small fortune to try and diagnose it before I pay for the engine to be dropped to check the actual turbos. 🤦🏼‍♂️🤦🏼‍♂️🤦🏼‍♂️

Simeon

We just took my wife's 2017 CS on a long road trip (9 hour drive) and I started getting the same problem. By the end of the trip boost was pretty much zero all the time and would never go up aside from occasional brief moments after throttle application and again drops to zero. Will be taking it to the dealer this coming Thursday.

JamesN

Simeon,
Please keep us (me) informed as I also have a 2017 CS which has the same problem. Only 23000 miles . Chicagoland dealer? which one?

Thanks

Jim

Simeon

Will do. I'll be taking it to the dealer I bought it from, Motorwerks Barrington. I'm very curious what it might be, it started happening again today after a few hours of on some twisty d mountain roads in Arkansas. The power loss is very noticeable when the boost goes away.

Smithydxb

Update: I’ve managed to record a code! P0234, so the overboost issue has now actually been confirmed, which is what I had seemed most obvious but we were never able to actually record it. Still not sure what is causing it as I didn’t have time to get it diagnosed, so I’ll get that done at the end of next week. I’m hoping its just a old hose or the N75 valve itself (the only one I haven’t checked or replaced yet) and nothing more, such as the actual turbos or actuators or similar part. Here’s hoping. Will update with solution once we find out the cause.

Mr. Merk

The wastegate(s) staying shut, and not opening to control the boost level. Either it is sticking, or not getting the boost reference from the N75. Hose off the wastegate? Leak in the line? From rodent damage? Faulty N75? If that's the case, is it now eliminating boost levels by manipulating the diverter valves open?

Definitely not the diverter valves. Those of you having this issue with your V6s, get the codes checked as these are totally different engines and may be something totally different. The car will cut out boost as a safety feature if something else is wrong.

Smithydxb

Yes, my hope is that it is not the wastegates getting stuck as that is a larger (read more expensive) issue, than an issue with a hose. I’m hoping its just a small issue such as a leak in a hose, causing issues elsewhere, as that can easily be fixed quite quickly and without digging right down into the engine. It’s going in on Friday so we’ll see what they say. I’ll have them check hoses and N75 first, before moving on to the wastegates.

4ocious

I use to live in Saudi where it does get very hot and humid. Based upon your description I suggest it might be your turbos are vapor locking which will clear with a restart. I also think you're using fuel that's too rich for your CTT which may cause unexploded fuel to remain in the cylinders. Try using a tank of 95 vs 98, I don't think you'll notice any change in performance but you may get better fuel burn. JMO-

Simeon

Sorry for the delay. The new post on here reminded me I have not updated my issue on the 2017 CS. Got it back from the dealer and they said it needed a DME update. I have not noticed the issue since but we have also not driven for over 4 continuous hours since then either.

-Simeon