Engine drone sound
11-03-2013, 07:55 PM
#1
Engine drone sound
Driving home today all of a sudden the engine/ exhaust started making a loud droning sound, almost as if the muffler fell off. I had just taken a long sweeping on ramp at a decent speed onto the highway. The droning happened between 3-4k rpm and lasted for about 10-15 min of highway driving, then disappeared. I had this happen 2 other times, but only lasted for maybe 10-20 seconds. Power generally seemed ok, and no check engine lights. Anyone have any thoughts?
11-03-2013, 08:55 PM
#2
Burning Brakes
Normal. In a stock S model and with PSE exhaust valves open automatically at 3500 and with a "map" in the DME control as function of engine speed and load:
engine speed greater than 3500
Load: slight, partial load acceleration with an air mass of 400 mg/stk...
when either of these conditions exist the DME control unit send signal to rear end electronics which activate the electropneumatic switching valve.
You can also "acheive" this sound by switching on the sport or sport+ or, in the alternative, PSE if you have it.
A few months ago i was hard accelerating into traffic without sport or pse and it scared the cr*p out of me - like, "who did that?" totally unexpected.
engine speed greater than 3500
Load: slight, partial load acceleration with an air mass of 400 mg/stk...
when either of these conditions exist the DME control unit send signal to rear end electronics which activate the electropneumatic switching valve.
You can also "acheive" this sound by switching on the sport or sport+ or, in the alternative, PSE if you have it.
A few months ago i was hard accelerating into traffic without sport or pse and it scared the cr*p out of me - like, "who did that?" totally unexpected.
11-03-2013, 09:42 PM
#3
Sorry, should have been more specific - I don't have an S or PSE, its a 2013 C2 with just under 8k miles. I have heard the PSE and am actually in process of shopping for an aftermarket exhaust. This sounded like an old beater car whose muffler has worn out or fallen off.....but after a bit the sound went away.
11-04-2013, 07:49 AM
#5
Burning Brakes
Justin, I am sad to read this complaint but at the same time quite pleased!
Let me tell you my story.
My new C2S was about six months old, maybe 3,000miles. One morning I started up (after having driven somewhere already) and immediately thought the car sounded, well, 'rough'. My first idea was that the SPORT button was on but, nope. Pulling away, I isolated the noise - a sonorous drone, rather like an old 4-cylinder engine - to between 1800 and 2600rpm, after which time it appeared to disappear. It was most noticeable under load although not necessarily hard load. Power appeared unaffected (but more of that later....). I could even feel some harshness through the pedals and steering-wheel.
For two days I drove around trying to decide if I was imagining it. I knew I wasn't when my wife took the car somewhere and on returning said to me; "I think that button that makes the exhaust louder is switched on.". And it wasn't. Bless her, she's a sweetheart and not really tuned in to cars but I thought if she heard it, I wasn't imagining things. So I went back to the dealer next day.
I get on well with my dealership; bought three cars from them and really have no gripes whatsoever. I talked to the service guy who called a mechanic out to come on a drive with me. I took the car into the rev-band and said; "There - that's the noise", expecting him to say OK, I hear it. But he didn't. Nope, I don't hear a thing. We drove up and down, under load, and he said it sounds like every other S.
I was a bit taken aback, I must say. Anyway, I took him back to the dealer and he and the service guy and I had a chat and the result was that the car was normal.
I drove away thinking I was nuts; however, two days later I thought that I wasn't nuts so I took it back again. Service guy sent another mechanic out with me. We drove up and down again - the booming/coarse sound at low revs was plain to me but again, the second mechanic said he heard nothing and the car sounded OK. I think the service guy could see I was a bit peeved so he asked me to bring the car back the next day and leave it with them - which I did.
Yet another mechanic attended to the car that day; this guy drove me in my car back to my office (which is just up the road from the dealer) so I could let him hear the noise. On the way there he said he couldn't hear a thing but he'd run some tests and also take another car on back-to-back drive just to check.
At the end of the day I collected my car and, again, was told that actually there was nothing they could find, they didn't notice a noise and everything was OK.
So that was three different tech guys all telling me the same. Which led me to three possible conclusions:
- I was imagining it, there was no noise really.
- There was a noise but techs didn't pick it up.
- There was a noise but for some reason the 'party line' was to say there wasn't.
The first of these I could dismiss; I know my car and, besides, my wife's comment confirmed it.
The second was possible but, frankly, unlikely.
The third was actually alarming; could that be?
I felt I'd played all my cards, though, and on the face of things the dealership had done everything they could to address my issue. I drove off thing that that's just what this car is going to sound like in future.
Extraordinarily, two weeks later, driving to work one day the noise stopped. Just as suddenly as it started it simply disappeared. OK, I thought, whatever it was - Porsche poltergeist - it's gone.
That was two months ago.
Fast forward to two weeks ago, I'm driving to work and lo!, the sonorous, drone starts again. Same thing; between 1800 and 2600rpm a deep, coarse noise, quite rough. So what to do? As )bad) luck would have it, two days later I picked up a 1cm bolt through a rear tyre. I called around for quotes and the dealer was cheapest.
When I took the car in - I was going to wait while they fixed the tyre - I mentioned to the same service guy that the droning had stopped but had started again just a couple of days previously. I asked him if, in the period since, any other owners had mentioned something similar and he assured me that they had not.
So, I'm drinking some coffee in the lounge waiting for my car and the service guy and a mechanic - a different one to the previous three - wander across to me. The mechanic says that he thought my car sounded rough so he hooked it up and noticed a random mis-fire. Not on a particular cylinder (eg; a coil problem) but across all six. I felt like a hypochondriac who is finally told he really has got cancer after all........
The service guy looked a bit sheepish. Anyway, the mechanic asked if I ever used low-octane petrol (95 instead of 97) and I said I did on occasion. He said the ECU sensed the octane and altered it'self slightly to compensate and perhaps it was changing over from a 95 to a 97 setting which, apparently, could take a few days. Please would I run only 97 for a few weeks and see what happened.
I drove away feeling enormously relieved and vindicated. The explanation seemed sound - what do I know about modern ECUs? When I got back to the office I checked my last couple of months credit-card slips and realised I hadn't actually used a low-octane for a long while, certainly not for the previous eight weeks anyway. So I called the service guy back and told him I'd actually ruled the 'octane' thing out. He said let's book the car in, which we did. It goes in this week.
The final thing is when we booked it in I said it was not impossible that the noise would disappear before the appointment so could I take the mechanic for a drive right now - which is what we did. This ame guy got in, started up and drove 50metres before saying; "That sounds rough......". We went up and down and he absolutely agreed with me. Then said, let's get another car right now and see what that sounds like. Which we did; again, just 50metres down the road he said "This car doesn't make the noise at all....".
I recapped the whole sorry saga to this guy including my scathing concern about his colleagues. He assured me that he had kept a copy of the read-out from that morning and he'd get to the bottom of it. Apropos the possible power - or loss thereof - issue, he acknowledged that with 395hp even losing 10% probably wouldn't really be noticed in daily driving.
I have no idea, Justin, if this chimes with your issue; if not, at least it's an advisory for any of you who maybe stumble across a similar problem. i shall, of course, let you know what happens - they will have my car for a few days later this week.
Let me tell you my story.
My new C2S was about six months old, maybe 3,000miles. One morning I started up (after having driven somewhere already) and immediately thought the car sounded, well, 'rough'. My first idea was that the SPORT button was on but, nope. Pulling away, I isolated the noise - a sonorous drone, rather like an old 4-cylinder engine - to between 1800 and 2600rpm, after which time it appeared to disappear. It was most noticeable under load although not necessarily hard load. Power appeared unaffected (but more of that later....). I could even feel some harshness through the pedals and steering-wheel.
For two days I drove around trying to decide if I was imagining it. I knew I wasn't when my wife took the car somewhere and on returning said to me; "I think that button that makes the exhaust louder is switched on.". And it wasn't. Bless her, she's a sweetheart and not really tuned in to cars but I thought if she heard it, I wasn't imagining things. So I went back to the dealer next day.
I get on well with my dealership; bought three cars from them and really have no gripes whatsoever. I talked to the service guy who called a mechanic out to come on a drive with me. I took the car into the rev-band and said; "There - that's the noise", expecting him to say OK, I hear it. But he didn't. Nope, I don't hear a thing. We drove up and down, under load, and he said it sounds like every other S.
I was a bit taken aback, I must say. Anyway, I took him back to the dealer and he and the service guy and I had a chat and the result was that the car was normal.
I drove away thinking I was nuts; however, two days later I thought that I wasn't nuts so I took it back again. Service guy sent another mechanic out with me. We drove up and down again - the booming/coarse sound at low revs was plain to me but again, the second mechanic said he heard nothing and the car sounded OK. I think the service guy could see I was a bit peeved so he asked me to bring the car back the next day and leave it with them - which I did.
Yet another mechanic attended to the car that day; this guy drove me in my car back to my office (which is just up the road from the dealer) so I could let him hear the noise. On the way there he said he couldn't hear a thing but he'd run some tests and also take another car on back-to-back drive just to check.
At the end of the day I collected my car and, again, was told that actually there was nothing they could find, they didn't notice a noise and everything was OK.
So that was three different tech guys all telling me the same. Which led me to three possible conclusions:
- I was imagining it, there was no noise really.
- There was a noise but techs didn't pick it up.
- There was a noise but for some reason the 'party line' was to say there wasn't.
The first of these I could dismiss; I know my car and, besides, my wife's comment confirmed it.
The second was possible but, frankly, unlikely.
The third was actually alarming; could that be?
I felt I'd played all my cards, though, and on the face of things the dealership had done everything they could to address my issue. I drove off thing that that's just what this car is going to sound like in future.
Extraordinarily, two weeks later, driving to work one day the noise stopped. Just as suddenly as it started it simply disappeared. OK, I thought, whatever it was - Porsche poltergeist - it's gone.
That was two months ago.
Fast forward to two weeks ago, I'm driving to work and lo!, the sonorous, drone starts again. Same thing; between 1800 and 2600rpm a deep, coarse noise, quite rough. So what to do? As )bad) luck would have it, two days later I picked up a 1cm bolt through a rear tyre. I called around for quotes and the dealer was cheapest.
When I took the car in - I was going to wait while they fixed the tyre - I mentioned to the same service guy that the droning had stopped but had started again just a couple of days previously. I asked him if, in the period since, any other owners had mentioned something similar and he assured me that they had not.
So, I'm drinking some coffee in the lounge waiting for my car and the service guy and a mechanic - a different one to the previous three - wander across to me. The mechanic says that he thought my car sounded rough so he hooked it up and noticed a random mis-fire. Not on a particular cylinder (eg; a coil problem) but across all six. I felt like a hypochondriac who is finally told he really has got cancer after all........
The service guy looked a bit sheepish. Anyway, the mechanic asked if I ever used low-octane petrol (95 instead of 97) and I said I did on occasion. He said the ECU sensed the octane and altered it'self slightly to compensate and perhaps it was changing over from a 95 to a 97 setting which, apparently, could take a few days. Please would I run only 97 for a few weeks and see what happened.
I drove away feeling enormously relieved and vindicated. The explanation seemed sound - what do I know about modern ECUs? When I got back to the office I checked my last couple of months credit-card slips and realised I hadn't actually used a low-octane for a long while, certainly not for the previous eight weeks anyway. So I called the service guy back and told him I'd actually ruled the 'octane' thing out. He said let's book the car in, which we did. It goes in this week.
The final thing is when we booked it in I said it was not impossible that the noise would disappear before the appointment so could I take the mechanic for a drive right now - which is what we did. This ame guy got in, started up and drove 50metres before saying; "That sounds rough......". We went up and down and he absolutely agreed with me. Then said, let's get another car right now and see what that sounds like. Which we did; again, just 50metres down the road he said "This car doesn't make the noise at all....".
I recapped the whole sorry saga to this guy including my scathing concern about his colleagues. He assured me that he had kept a copy of the read-out from that morning and he'd get to the bottom of it. Apropos the possible power - or loss thereof - issue, he acknowledged that with 395hp even losing 10% probably wouldn't really be noticed in daily driving.
I have no idea, Justin, if this chimes with your issue; if not, at least it's an advisory for any of you who maybe stumble across a similar problem. i shall, of course, let you know what happens - they will have my car for a few days later this week.
11-04-2013, 08:45 AM
#6
Advanced
Sorry, should have been more specific - I don't have an S or PSE, its a 2013 C2 with just under 8k miles. I have heard the PSE and am actually in process of shopping for an aftermarket exhaust. This sounded like an old beater car whose muffler has worn out or fallen off.....but after a bit the sound went away.
11-04-2013, 08:47 AM
#7
Good God you brits write long stories!
My guess is you're hearing the symposer which opens up under certain conditions like heavy throttle - in my C2 I've had people comment they thought it sounded like I had an outboard motor out back!
My guess is you're hearing the symposer which opens up under certain conditions like heavy throttle - in my C2 I've had people comment they thought it sounded like I had an outboard motor out back!
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11-04-2013, 09:02 AM
#8
Burning Brakes
I doubt that; it is unlikely that the mis-fire on random cylinders - which would also explain a sonorous drone - has anything to do with any symposer.
11-04-2013, 12:59 PM
#9
draxa - thanks for your reply, this is exactly in line with what mine was doing, I just haven't been able to repeat it yet. I thought about the gas issue. I always fill with premium, but last time I filled up it wasn't at a gas station I normally go to, not sure if the attendant pressed the right button ( don't get me started about being in one of the only states in the nation where you can't pump your own gas). I just filled with premium yesterday again, but this droning happened right after that(maybe if it was bad gas it hasn't gone through the system yet). Looking to hear what the diagnosis is after they have your car at the shop for a few days, prob going to bring mine in next week.
Last edited by Justin N; 11-04-2013 at 10:27 PM.
12-05-2013, 06:20 AM
#11
Burning Brakes
Hi Justin. My apologies - I got my car back a week ago and have been waiting until I was certain before updating you.
They quickly diagnosed that for some reason, the sound-symposer baffles in my car were 'stuck' partially open. They identified a part - I believe they call it a 'rear control unit' - as being faulty. They also thought that there may have further, tertiary issues relating to this part's malfunction - the aforementioned random misfire as well as perhaps the PDK behaviour.
So they ordered a new one; not so simple as the dealer said it could take anything from two to fourteen days to arrive. (It was the latter; but thankfully, those kind people gave me a brand new Panamera for the period - which car, by the way, both my wife and I were extremely reluctant to hand back because we liked it so much......).
This control unit is (I understand) book-sized and is an electronic gizmo which deals with - among other things - the functions when "SPORT" is pressed. When it arrived, there was some difficulty in matching the coding of the new unit with the car's existing ECU and that issue delayed things as well.
So, two weeks later (last Friday) they call and say the car is fixed. I collected it (bye bye Panamera, we'll miss you....) and within 100metres of driving out of the dealer I could tell there was a difference.
In my earlier post i mentioned how, like you, my issue with a booming/coarse noise had arisen quite suddenly after six or seven months of regular driving. What I now realise is that even before that most obvious manifestation, my car probably had an underlying issue since the day I first collected it. There is no doubt that my car is not only cured of the intermittent complaint but is also behaving perhaps 5-8% better (ie: smoother, quieter, sharper and more linear in low-end performance) than it ever has done. I loved it before but now....it's just better.
I thanked the technical manager as well as the mechanic who originally concurred with me that there was an issue; he also took care of the repair.
Can't say for certain that this is the same issue as your car is suffering from but it sounds remarkably congruent; I would get them to check the 'rear control unit' and try and persuade them that this device can malfunction intermittently. If possible, get them to check the car when it is booming.
Good luck with that, Justin, I wish you as good a result as I have had.
(And for WCE who prefers the shorter trans-Atlantic version;
I'm like "Hey!"
They're like "Dude, no?"
And so I'm like "Yeah, really."
And they're like "OK"
And then I'm like "Radical, Dudes.")
They quickly diagnosed that for some reason, the sound-symposer baffles in my car were 'stuck' partially open. They identified a part - I believe they call it a 'rear control unit' - as being faulty. They also thought that there may have further, tertiary issues relating to this part's malfunction - the aforementioned random misfire as well as perhaps the PDK behaviour.
So they ordered a new one; not so simple as the dealer said it could take anything from two to fourteen days to arrive. (It was the latter; but thankfully, those kind people gave me a brand new Panamera for the period - which car, by the way, both my wife and I were extremely reluctant to hand back because we liked it so much......).
This control unit is (I understand) book-sized and is an electronic gizmo which deals with - among other things - the functions when "SPORT" is pressed. When it arrived, there was some difficulty in matching the coding of the new unit with the car's existing ECU and that issue delayed things as well.
So, two weeks later (last Friday) they call and say the car is fixed. I collected it (bye bye Panamera, we'll miss you....) and within 100metres of driving out of the dealer I could tell there was a difference.
In my earlier post i mentioned how, like you, my issue with a booming/coarse noise had arisen quite suddenly after six or seven months of regular driving. What I now realise is that even before that most obvious manifestation, my car probably had an underlying issue since the day I first collected it. There is no doubt that my car is not only cured of the intermittent complaint but is also behaving perhaps 5-8% better (ie: smoother, quieter, sharper and more linear in low-end performance) than it ever has done. I loved it before but now....it's just better.
I thanked the technical manager as well as the mechanic who originally concurred with me that there was an issue; he also took care of the repair.
Can't say for certain that this is the same issue as your car is suffering from but it sounds remarkably congruent; I would get them to check the 'rear control unit' and try and persuade them that this device can malfunction intermittently. If possible, get them to check the car when it is booming.
Good luck with that, Justin, I wish you as good a result as I have had.
(And for WCE who prefers the shorter trans-Atlantic version;
I'm like "Hey!"
They're like "Dude, no?"
And so I'm like "Yeah, really."
And they're like "OK"
And then I'm like "Radical, Dudes.")
12-05-2013, 07:26 PM
#12
Draxa- thanks very much. I have been able to figure out how to reproduce it, basically take a long on ramp a bit
fast. Something screwy with the sound symposer cold certainly explain it. I actually had the engine cover release cable come fail a few months ago and I couldn't open the trunk. The mechanics were certainly messing with the area around the symposer when replacing it. Going to take the car in sometime next week.
fast. Something screwy with the sound symposer cold certainly explain it. I actually had the engine cover release cable come fail a few months ago and I couldn't open the trunk. The mechanics were certainly messing with the area around the symposer when replacing it. Going to take the car in sometime next week.
12-06-2013, 10:00 AM
#14
Burning Brakes
Wouldn't swear to this, but I think the "noise" increaser in our cars is basically a baffle opening up to allow more intake noise into the cabin. Sound Symposers actually generate simulated noises, don't think that's what on our cars. Some cars that DO have true sound symposers are various BMW's and VW's.
12-06-2013, 11:51 AM
#15
Burning Brakes
Wouldn't swear to this, but I think the "noise" increaser in our cars is basically a baffle opening up to allow more intake noise into the cabin. Sound Symposers actually generate simulated noises, don't think that's what on our cars. Some cars that DO have true sound symposers are various BMW's and VW's.
Looks like you are correct. I'm no technical genius so can't really comment; however, this from Porsche:
"......the Sound Symposer directs intake noise into the interior at the push of a button. This is achieved by an acoustic channel picking up the intake vibrations between the throttle valve and air filter. The acoustic channel incorporates a membrane that transmits the vibrations as an engine sound into the A-pillar. A controllable valve located in front of the membrane enables the Sound Symposer to be activated or deactivated by means of the Sport button.""
This referred to the V8 engine but I'm guessing the operation is much the same in our cars.
Looks like you are correct. I'm no technical genius so can't really comment; however, this from Porsche:
"......the Sound Symposer directs intake noise into the interior at the push of a button. This is achieved by an acoustic channel picking up the intake vibrations between the throttle valve and air filter. The acoustic channel incorporates a membrane that transmits the vibrations as an engine sound into the A-pillar. A controllable valve located in front of the membrane enables the Sound Symposer to be activated or deactivated by means of the Sport button.""
This referred to the V8 engine but I'm guessing the operation is much the same in our cars.