Cyberbug

Interesting, so you went with cat bypass.

i plan on a tune in future but doing headers and exhaust for now. Just thinking if I will have to do sport cats with tune

MidEngineRules

If there was ever a thread that illustrates the adage you should buy the power (stock) you want, this is it.

spdracerut

Double check the hoses going to the wastegate actuators. The wastegate is open by default, so if the there's a leaks somewhere between the wastegate actuators and the vacuum source, there will be no boost.

Bartosz Surowka

Good news your not the only one.
I'm having the same issue.
I also have a 2017 C2.
It sounds like all the boost is blowing out through the throttle body somewhere. I've taken the car apart a few times already to try to look for it and finally gave up and dropped it off today for the smoke test.

Ryan52589

I had a very similar sound. I did the smoke test, pressure checks, dropped the car off to AMS, Porsche, etc.
Finally I tried cat bypass pipes and I haven’t had an issue since.. soo if you don’t find any issue with lines.. try the bypass pipes or sport cats would work too.

Bartosz Surowka

I have the 2017 991.2 Carrera with 11k miles on it.
I did install the Fabspeed x-pipe. stock exhaust was too quiet for me.

do you have any sound recording of how your 991.2 sounds without the cats?

I've been running catless on all of my previous sports cars but the last one i overdid. put on 3 inch down pipes into 3 inch exhaust system into a 3.5 inch tailpipe. that turned on people car alarms when i would leave at 5am to go to a track meet.

Thanks again for this post! I was really freaking out that I broke the car. haha.

Ryan52589

I’ll take a video tomorrow and post it in this thread. Sounds amazing imo, not too loud at all. Do you have sport chrono?

pfbz

If a 2017 GTS and S with powerkit use the same cats as the base, seems like the cats should be able to handle a Cobb tuned base....

So if bypassing the cats really solved the problem, then IMHO it begs the question: Were the carts defective or fail for reasons unrelated to the tune? Or did the Cobb tune accelerate the cat failure?

I'm currently looking for a 2017 base with the intention of putting .a Cobb tune on it, so I'll be following this thread a bit more.

polobai

No issues with my stock cats on Cobb stage1 for a few months now with about 1500 miles under her belt. I am in process of installing cat bypass pipes currently-not because of cat failure but rather to get a bit more power and sound from the car.


Cleaned up and ready to reinstall

Bartosz Surowka

It's a base model, no chrono. Just pure cobb tune.

Also an update.

My mechanics electrical mechanic found a solenoid that was stuck in the open position. A $34 part and it fixed the problem. Full boost!!!

It has something to do with the boost control on the driver side of the motor. Let me know. I can find out the part number, maybe it will help others.

Time to upgrade the tires, was able to spin these in 3rd gear!

Ryan52589

Excellent find! Let us know the part number if you can!!
I would like to have one on hand just in case mine starts acting up again!

Heres the video. The initial revs are in sport plus mode and then you can hear it switch to sport mode around 32 seconds, it doesn’t backfire in sport mode. There is more turbo spool at idle in sport plus