bhgt2

Can you elaborate on this a little? I've tracked my car with sport headers + IPE exhaust, sport headers + stock exhaust, and soon sport headers + fab speed exhaust (with the valves disabled). I've never had a CEL pop-up thankfully. Yet to see with fabspeed.

(The headers are IPE sport headers)

CAlexio

i'm glad to hear it. I'm just reporting what one shop manager said. he wasn't referring to Fabspeed.. he just said that he clears cells all the time for people who have sport headers, and it happens to those who track. Something about engine at high revs having the ecu sense the different backpressure. He said it's no big deal, and dealer is happy to do it. but that porsche at any time can find out as the ECU is collecting data constantly on many parameters.

I'm excited to get my sport headers installed.. i'm going to enjoy the sound with those and my pse for awhile.. then I'll add the exhaust cause it's a work of art and their graph shows the real world improvements with it.

bhgt2

My favorite combo was sport headers with stock exhaust. Now I have the fabspeed on with valves open and it is way too loud for my liking. I have a couple of track events over the next couple of weeks, then I'll probably go back to stock exhaust over the off-season

jmartpr

Same case here...I have the "other brand" sport headers and log so far about 700 miles with them. NO CEL or problems so far.

jmartpr

+1 on this......sound is awesome. I have an exhaust system on its way here with no flaps and I worry it may be a bit too loud but we will see, all exhaust systems are different.

Jimmy-D

Any problem with Drone?

John@Fabspeed

CAlexio, very glad to hear you are enjoying the Spyder so far! And boy that is one heck of a garage haha. My favorite is the Pagani

It sounds like you have a great relationship with great Porsche rep, which is sometimes a rarity so congrats! In regards to the check engine lights, we use HJS cats and a check engine light is very uncommon especially when being used primarily for street use. For the 981 in particular I have yet to see/hear of a single CEL occurrence. However if you are tracking the car in the high RPMs with cats (factory or aftermarket) some may hit a point where cats can't scrub the exhaust well enough to maintain readings within spec if the ECU is running a cat monitoring test at that time. This happened to me once when tracking my older Z28 with high flow cats, although they certainly weren't HJS haha. Typically the CEL goes off a short period later the next time the ECU runs the test and everything checks out okay, or you can clear the code manually with an OBDII scanner or COBB Accessport.

bhgt2

Oh yeah, all day long

John@Fabspeed

Can you elaborate on that a bit for us? With valves closed or open, under what conditions, extent of the drone, etc? We put an extensive amount of mileage with our Sport Header/Valvetronic combination and with valves closed we experienced minimal drone characteristics

CAlexio

Yes, to clarify he was mentioning cells being thrown generically, not specific to fabspeed at all. And specifically said that if I were to get a cell they would happily clear it...

Funny how he basically said that Porsche can tell any modification anyway, but that getting the whole system is the only way to go.. Encouraging me to finish it with your exhaust...

We'll be talking soon

Beantown Kman

Can you explain the causes of exhaust drone and what you do to mitigate the problem? Why do some exhausts have more drone than others?

bhgt2

My story with the fabspeed exhaust is mentioned in another thread, however I received the first batch with the valves reversed and then fabspeed arranged for it to be shipped back and fixed. I received it and installed it this week and at high RPM the valves start to close up, causing the car to choke and throw up a CEL. This is why I can't run it with valves closed. I disabled the valves manually to have them open all the time, and that is why it drones.

John@Fabspeed

In regards to issues you are having with the vehicle choking and throwing up a CEL in the high RPMs, we need some insight on the details of the issue and tried a couple times to give you a call. Please give us a call at your earliest convenience for us to work through the symptoms, as some crucial information is being lost in translation via email. We have our techs and tuner ready to rock and roll for you.

jmartpr

That kind of sound like the spring on the valves/flaps can't take the exhaust gas pressure created at high RPM. If you close the OEM ones by hand with the car off you will feel that spring tension on the valves.


I haven't checked how the OEM system works in detail, but looks like with zero vacuum from the engine the valves stay open using that spring pressure. That's why when you start the car (Stock) it sounds very nice (valves open) until you get a decent amount of vacuum from the engine and the valves close, unless you press the PSE button to keep them open. So the spring has to be stiff enough to open the valves and keep them open but not too stiff that the vacuum actuator can't overcome the spring tension and close them.

bhgt2

That was my theory as well. When you open the flaps, that means you remove all vacuum from the system (they are open when there is no vacuum). So why is it that they close at high RPM? I thought that at high RPM the system loses vacuum and closes the flaps but that is not how it works. My other theory is that the flaps aren't perfectly horizontal when they are open so at high pressure they are somehow pushed down and closed by the exiting exhaust fumes. Not an expert and don't know if that makes sense, but I'm troubleshooting with fabspeed now.