AdamSeen

A few months ago I was driving in my 981 S with Sports Exhaust turned on, not driving fast or aggressively and all of a sudden I hear a noise from underneath my car like air was being squeezed out [or in] of a small opening.

Since that day the overrun sound has mostly disappeared. There are barely any pops or burbles in my exhaust note when letting off the gas pedal and any noise that comes out now is lacking in bass and poise.

I’ve taken it to the Porsche garage and still under warranty. It took them several hours to convince them there was a problem. They checked out the exhaust and it was all working so said they would take it in for the day to record sound clips to send to porsche.

I thought that meant they would setup the car on rollers and use a microphone to listen to the exhaust note. Instead they just recorded a video on one of the technicians phones of them turning the sports exhaust on and off whilst the car was moving. Which was useless, as the sports exhaust is working fine. It's the overrun that isn't.

It’s been submitted as a issue to Porsche for 4 months now and I’ve heard nothing.

Could anyone guess what the problem could be?

Macster

Time to ask the Porsche "garage" why it has not heard back from Porsche.

You are owed a reasonable degree of skill, experience, and care when you have your Porsche in at a Porsche shop for service, repair, diagnostics.

From your post you are not getting at least 2 of the 3 items listed above.

You need to speak to the GM of the dealer, I assume by Porsche garage you are referring to a Porsche dealer, and let him know how poorly the service department has been doing with regards to your car.

(If you are not dealing with a Porsche dealer and its service department my advice is you should be.)

If his service department can't or won't help you with a warranty issue ask him who at PCNA you can contact to ask where you should take your car for warranty work.

If you want a guess...

CEL off? Engine runs ok?

If no CEL and no untoward engine behavior I'd guess there's a leak in the exhaust system *after* the converter and its post converter O2 sensor.

Could be loose hardware or a crack/split in an exhaust system component.

However, I'm not sports exhaust savvy and while you claim this is working I wonder if it really is working, at least 100%?

extanker

did you check the burble fluid ?

AdamSeen

I am dealing directly with a Porsche dealer. They ran through some standard tests and engine tests and everything is working well (no CEL lights, or similar). The excuse that I've heard multiple times for lack of overrun was: "soot build up". I would say that might be a valid excuse if my car ran on coal.

My guess as a non-informed user and without any manuals of the inside of the car would have been a leak of some sort in the 'vacuum/low air pressure pipes' due to the noise I heard when the problem arose. It's good to see you are thinking along the same lines and I will go back to the dealer either Thursday/Friday with a bit more understanding of how I should approach the problem with them.

Thank you for your help, Macster. I will update once I have more info from them.

And extanker - it was the first thing I checked. I use the NO (Nitrous Oxide) BS fluid and keep it topped up regularly.

EDIT: I've just noticed I've posted this wrong forum and should be the 981 forum. If a moderator or admin sees this, please can you move it to the correct forum - Thank you!

paulofto

Not to mention the muffler bearings . . .

Macster

Best of luck getting this sorted out. That "soot build up" as a reason for the behavior reads lame to me. Sort of similar to "they all do it". Should have asked soot build up where? What's the solution? Or once the soot builds up there no "cure"? Is there a technical service bulletin from Porsche on this? Can I have a copy?

AdamSeen

I've just got off the phone to them - they were being unusually friendly and helpful. They said they checked the whole system before. When I mentioned vacuum pipes, they said they were checked also.

I've been invited in on Tuesday to have a look over the car with a technician and I've taken them up on the offer so let's see what comes of that.

The questions you're asking are very helpful Macster - I will use those objections come Tuesday.

AdamSeen

I took it into the dealer today. They spent two hours with me looking at the car on the garage, which I was thankful for. They can't seem to find a leak in the system and are not sure what's causing it. But we drove around in my car and another one that had a fully working sports exhaust. Even after spending some time with them both, I couldn't quite put my finger on a definitive difference between the two.

When I listened to the sound clips, it all became clear:

2nd gear in cabin.
981-test-car - Inside the other car 2nd gear
981-my-car_-2nd-gear - Inside my car 2nd gear

1st gear outside cabin.
981-my-car_-at-rest-1st-gear - My car
porsche 981 sound clip sports exhaust - Porsche comparision, same setup (how my car used to sound)

You'll notice on all clips of my car, the lower frequencies sounds have reduced, the bass is mostly absent and very tinny. It is very clear when playing the 1st gear outside cabin clips back to back.

It seems the overrun, whilst doesn't sound right, just highlights the problem more as you expect more bass, but I'm not sure it is the problem - The bass has disappeared and I'm not sure why.

The technician is going back to national level now to see if they can figure it out.

AdamSeen

They took my car in for a couple of days to have a look at. They lent me a 718 during those days... it's exhaust sounds deeper than mine with it's 4 cylinder turbo.

The technicians had a look inside the exhaust with a camera, ran multiple tests and there was also advice given by Porsche national office - But ultimately they concluded there isn't a problem.

So I asked if they'd also be happy enough to sell the car? They said yes - So now I've asked them to sell it for me.

They doesn't seem to be other options at this point apart from sell it, they cannot figure it out and in-spite of the car being excellent, it no longer gives the same thrill anymore without that deep bass it once had.