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MG MGF Technical - Irritating Whine

I've recently noticed that when sitting in traffic I can hear a very high pitched whine from the engine ( I know it's not my ears cos it vanishes when the engine is switched off!).

It sounds a bit like an old TV does when switched on - sort of electrical and very high frequency. Anyone else know what this is and whether it can be remedied - it's driving me nuts!

BTW - car is a 2000MY VVC.

James
James

sorry, thought this was another Dirk thread.


Never heard this on my vvc.
Gareth

Hi James,

Is it your radio??

Mine does the same, I have a Sony MD head unit in and the high-pitched frequency sound comes through the speakers (although I'm not sure if the speakers have been changed) while playing MD/CD or radio.

Passengers have commented that it sounds quite cool. But it is at a low level and not too loud to be annoying. It dissapears if I turn my radio up.

I Could be wrong in your case though as I'm not a techie....

Curtis
Curtis

Could be your fuel pump - this is normally audible as you turn the ignition on, before you start the engine - I normally wait for mine to stop before cranking the engine.
Can you hear it easily from outside the car ?

Steve
Steve

Could be your cam belt, some whine but you can't hear it at higher revs.
Bruce
Bruce Caldwell

Curtis,

Thought it was the radio but still there when switched off but I wondered whether speakers can still pick up some kind of elctro-magnetic thingie anyway??

As for the fuel pump, Steve, I know that sound and that's not it I'm afraid. I can only compare it to when you've been to a loud club or gig and your ears are ringing - except it's not my ears!!! (doctor)

James
James

I get it in mine to a 96 (P)
i have just assumed its part of the car, mine seems to be coming from the right hand side towards the back.
Nick Walters

James

Have a look at the "cam belt tensioner" thread of last week. It could be the same and if so it's easily sorted by slackening off the belt.

Hope it works

Tom
Tom Grayling

Have just noticed a similar sounding noise in my 98R VVC. It has only appeared recently - no apparent reason as nothing has happened/been done to the car for months. It is as you describe - a high pitch electrical sounding noise - whine is the closest word although perhaps this word implies a fluctuating pitch which it isn't. It does dissapear with more revs but only I think because it becomes inaudible. I only really notice it when idling. Any other ideas from anyone?

Dave

P.S. First time I've ever posted a fault type query in three and a half years of ownership.
Dave

Sounds even more like the fuel pump to me.
Dot

I got this problem........




.......it's the wife.
Steve

No, don't tell me Steve, she's in the boot!?
Bruce Caldwell

how'd you guess that...? No, usually comes from around the passenger area. LOL
Steve

I had something similar, and it turned out to be the engine-coverplate not being put on tight enough.

Just throwing another possibility in the ring.

Bas
Bas

James
Its very audiable when turning off the engine on my 97 N vvc . It seems to carry on for a couple of seconds.

Is it something to do with the VVC as all above entries seem to be from the vvc model.

Dot
Does the Elise do the same ( dont know if that is a vvc model)

Lister

Mine isnt a VVC and i have the whining noise, its a really high pitched whistle only just noticeable except when you have a headache then it rings in your ears :0)
Nick Walters

ok .
The fuel pump is at the left hand side of my car just behind the passenger compartment. so i wouldn't have thought it could be that. Is there a fan at the air intake at that side. i wonder if it is like a computer fan which starts to whine when the bearings get dirty or loose the grease?

Only a couple more suggestions to throw into the pot.

Lister

My Elise is a VVC yes. It makes so many rattles & clonks, it's difficult to tell what's (ab)normal sometimes :o)
Dot

Could it be the Alternator? They wine sometimes when charging at a high rate, or might be the bearings.
Nick

I collected my new 1.8i last week. I noticed a very quiet, high pitched noise after i turned the engine off coming from the dark hole that is the engine bay. Seems to disappear after a few minutes after gradually getting quieter. Some MGF techie must know what it is!!!
David Evans


Hello all,
either a slight leak from a pressured coal-canister that collects gas-fumes OR a leak around the gas-filler . The sound of emtying the carcoal canister can in my car be heard during acceleration, a highpitched blowing sound. If the electromagnetic valve or any connections around this area are leaking it can give prolonged hissing sounds.
What is called gasoline IS really gas today ! Now using the cracking method instead of the old refining one gives a lot more components in the fluid that wants to escape as pure gas !

Regards , Carl.
Carl

Hi all,
One the note of a high pitch whine, one thing I've noticed on my F is that when the accelerator is depressed slightly there is high pitched noise that is from somewhere in the engine. It's has been in the dealers twice but as of yet they have been unable to identify where the noise is coming from. Anybody got any ideas or had a similar problem?
Michael

Carl - you're talking about things I never knew existed on a car! Explain more please.

James
James


Hi James,

if You open up the rear bonnet and release the protective black cover over the engine You will se a cylindrical black thingy at the left rear side. This is the charcoal canister that is supposed to store any fumes that is generated in the fueltank. When the car is at working temp. any trapped fluid and gas is injected into the inlet mainfold (just after the throttle ) . On the canister is a electromagnetic valve that opens on acceleration only to enrichen the total mixture to the engine. The hissing sound can easily be heard - at least in my car.
Apart from this I discovered that during hot days this summer my filler-cap was not totally sealed and some overpressure escaped there also giving a slight hissing sound. When driving for some distance and stopping at a petrolstation for a fillup one can also notice the rather strong vacuum in the tank. Some force is needed to release the filler-cap. On the other hand when the car has been in the garage for a few days it is the opposite - heavy overpressure in the tank and filler-cap almost ejects when released.

Doh ! To complicated for my English but I guess You will get the hint ?

Regards , Carl.
Carl

The noise you are all hearing is from the fuel tank vent - all cars have a vent and tend to make more noise when the tank is empty ish - because there is more pressure/vapour in the tank trying to escape though a very small hole -some cars have a one way valve - anyway - hence the very high pitch whistle

Quite often you hear a more pronounced whistle when taking the fuel cap off if you have run it low or its a hot day
TONY

I just saw the comment re the noise stopping when the engine is off -

Does the car have a return fuel hose??? Most fuel injection rails do and tend to dump extra fuel back in the tank once their up to pressure

If so this will pressurise the fuel tank slightly causing the vent to whistle especialy when engine is low revs - as less petrol is returned to the tank when running high revs!

So the whistle is in effect a cheap fuel economy gauge - :) when it whistles your saving money :)

Never heard it in mine - must be my lead boots:)
tony

James, Is it the processor clock/oscillator in the engine management system? My 2001 i.8 fires up the MEMS-3 as soon as the remote opens the doors. It shuts down some time after locking the car again. The sound is very similar to that you described but it is very faint and you might be able to hear it and put your mind at rest if you put your ear very close to it or use a mechanics stethoscope / screwdriver carefully on the controller casing; you'll find the MEMS a silver alloy box under the NS black panel on the engine grille in the boot. Try with and without the engine running. Our cars might be switched on diffferently but I think the MEMS is the same. If this is the cause I'm impressed if you can hear the noise from inside the car with the engine running - you clearly haven't been to enough gigs/nightclubs etc. You can't fix it if this is the 'problem' - it's just the computer 'talking to the car', pass the tabs would you... You could always turn the radio up - it seems to fix most noises on my classic car...
Ian

Health issue ?

Speaker behind the head is just like having a cellular phone near his head all the time ?

Arnaud
Arnaud

Ian,

I don't think my hearing is that good - the noise I hear is really noticeable in the cabin, engine running. As you mention gigs it's very much like the ringing you get after a particulalry loud club or gig. Very electrical and high frequency.

I think there's a number of good explanations here - but I think I'll just have to put up with it. The pain of explaining this to the dealer will be too much to bear - even basic stuff is a trial to get done.

Thanks for all your ideas though.
James

>Have a look at the "cam belt tensioner" thread of last week. It could be the same and if so it's easily sorted by slackening off the belt.

Aaaaaaaarghh!

I assume it is not the sound of the engine bay fan you are hearing, does it sound like a fan? Before I had the K&N drowning out the sound you get a sucking air sound when accelerating I assume this is as described above (or below in my case).

Would a leak in the inlet manifold make this kind of sound????
Tony Smith

David - I think your noise may be pressure being released from the cap on the coolant header tank. Next time you hear it after you've been for a run, take a look under the water/oil access flap - you'll probably find you can shut it up by tightening the lid... (be mindful that the liquid inside is HOT and under pressure!)

Ta,
Peet
Peet

James,
I have now noticed what you mean, or at least what I think you mean. To me it is an almost inaudibly high white noise sound. In fact, today it gave me a headache.
I found that I got rid of it by turning the heater fan off so perhaps it is something to do with the whistle of air through the convoluted heater tubes. Just a theory.

Bruce
Bruce Caldwell

James,
Speakers can indeed pick up stray interference even when the radio is turned off. If your alternator/spark plug leads ect. are not filtered/supressed your speakers may well produce noise on their own.
The speaker wires will act as antenna, and if unluckily they are the correct electrical length to efficiently receive this interference then the sound can be quite loud.
If you disconnect your speaker wires from the speakers, and the sound dissappears, then I suggest you change the length of your speaker wires, and suppress the offending vehicle component/s with suitable filter capacitors.
Hope this helps, I deal with similar problems on ground to air radios daily.
georeg

What a load of twaddle.

Have you any idea what field strength would be needed to induce enough voltage in an unpowered speaker lead to make an audible sound?

Even the 750kW Daventry World Service transmitter could only manage a crystal earpiece without amplification.
brianh

I think it's aliens trying to take over your mind.
Tony Smith

Brianh,
I am an electronics engineer, and work on similar problems daily. The most publicized anomalies are probably the people with filling that pick up radio stations, and they're not even using speakers. I assure you, I am right.
Also, the field strength within the cabin of a car from the white noise generator we call an alternator, is pretty damn high. Try attaching an antenna stub to an osilloscope, or spectrum analyser, then starting up your engine, you'll be very suprised.
I suggest you keep your insulting remarks to yourself, unless you really have direct experience in the matter with some positive suggestions you can make.
george

I've even heard emergency service vehicles' radio messages coming through a speaker without even having ANY wires connected. And have had a personal wierd experience - i picked up what i can only describe as a sweeping radar signal in the back of my head and it made me feel sick. It was near a river, but i couldn't see any traffic to speak of.
So electromagnetic waves can have profound effects on people and equipment. If it is an electronic oscillation that you are hearing then it could be anything from the ECU to a servo. Or it could be just the fuel thingy!
Nick
Nick

George

Does BSc MIEE CEng count?

It takes energy to move a loudspeaker cone. A speaker is a low impedance device connected by a few metres of cable. The electromagnetic field strength needed to induce sufficient voltage in the cable would probably stop your watch. Anyway, the alternator is suppressed quite well, otherwise the radio would not work.

Fillings are very sensitive as you will find out if you hold a bit of aluminium foil against a mercury amalgam filling. A few mV will do this.

brianh

1. <It takes energy to move a loudspeaker cone.>
Yes it does, but not much to produce an irritating whine.

2. <A speaker is a low impedance device connected by a few metres of cable.>
If the few meters of cable, just happens to be the electrical wave length, or an even harmonic of the wave length, it becomes a very efficient antenna. You obviously haven't studied your open/shorted wavelength antenna theory lately.

3. <The electromagnetic field strength needed to induce sufficient voltage in the cable would probably stop your watch.>
The voltage is only induced when the inductive field and electromagnetic field are 90 degrees out of phase (antenna theory), your watch is unable to act as an antenna, and is probably shielded against the possibility.

4. <Anyway, the alternator is suppressed quite well, otherwise the radio would not work.>
The radio will work whether the alternator is suppressed or not. The radio antenna is designed to pick up radio stations, not alternators. The receive frequencies of the radio are significantly higher than the approx 16KHz noise being generated through the speakers. The noise will still be there, only covered by the radio's higher volume.

5. <Does BSc MIEE CEng count?>
I guess not. I work specifically in this field, and will reiterate, RF does some strange things. Nick seems to be aware of this without your qualifications.
george

Now I know where the irritating whine is coming from
brianh

Brianh,
I suggest a good RCL band pass filter for your brain, and removing some of your noise generators. Perhaps that would filter out your whine.
george

Gentlemen, gentlemen,
Don't let's argue and be abusive about it. Life is too short. We don't even know if the noise is coming from the speakers and here you are at each others throats.
Bruce Caldwell

Theory and practice are completely different animals! OK, to move a speaker cone physically with ones hand takes a relativiley large amount of effort, but to get a sound from a cone requires only a tiny movement, so the effort is also tiny. If the wavelength is very short and powerful then the voice coil alone will have a current induced into it.
Nick (BLI, O-level Physics, 100mtr swimming, cycle profinciency, and turbine builder!)
;-)
Nick

I think it is a small pixie that got trapped in the headrest by an evil Rover trimmer and is now trying to get rescued by a dashing prince.

Don't you dare try to suggest that I am wrong as I have a double Hons and if you do I'll come over there and antenna theory your ass.
SBD

George,

Isn't is strange how quickly this BBS gets abusive - still it's better than road rage.

To answer Georges points objectively

<1. <It takes energy to move a loudspeaker cone.>
Yes it does, but not much to produce an irritating whine.>

We are looking here for a source of electrical noise, servo motor, alternator etc. It would be difficult to imagine more that a few hundred mW of radiated power at RF, very little in the audio band. The speaker and leads are a very low efficiency aerial and could only pick up a very small amount of the radiated power. I still maintain that speakers and leads alone and without any tuner or detection circuit could not pick up the sufficient power. I do know that standing next to a high power AM transmitter one can hear the broadcast on a piezo earpiece with nothing but an antenna but we are talking about 100s of kW. What is very possible is that, with the radio in its off position, it is still powered and picking up the noise in its audio amplifier stage.

<2. <A speaker is a low impedance device connected by a few metres of cable.>
If the few meters of cable, just happens to be the electrical wave length, or an even harmonic of the wave length, it becomes a very efficient antenna. You obviously haven't studied your open/shorted wavelength antenna theory lately.>

You raised the issue of white noise. This implies a random selection of frequencies so there would be a very small proportion of the radiated power corresponding to full or half wavelengths at the length of the speaker leads and we still do not have a detection circuit. A 2 metre cable is about the wavelength of a VHF radio signal and nothing in the car, apart from the keyfob, will be active in the VHF band.

<3. <The electromagnetic field strength needed to induce sufficient voltage in the cable would probably stop your watch.>
The voltage is only induced when the inductive field and electromagnetic field are 90 degrees out of phase (antenna theory), your watch is unable to act as an antenna, and is probably shielded against the possibility.>

Sorry but voltage is induced when the magnetic field is at right angles to the conductor and changing or when the electrostatic field is parallel to the conductor. Magnetic and electric fields are always at right angles.

<4. <Anyway, the alternator is suppressed quite well, otherwise the radio would not work.>
The radio will work whether the alternator is suppressed or not. The radio antenna is designed to pick up radio stations, not alternators. The receive frequencies of the radio are significantly higher than the approx 16KHz noise being generated through the speakers. The noise will still be there, only covered by the radio's higher volume.>

I suggest you try removing the suppressors from the alternator or replace the ignition leads with non suppressed copper leads. Then you will find out what the radio picks up. By the way, the wavelength of 16kHz is about 5km.


Speaking as someone who has spent a lot of time trying to noise proof control circuits in a power electronics environment I have a bit of an idea what I am talking about.
brianh

Sirs,
I was only suggesting a possibility. I'm not usually in the mode of insulting people, and I'm sorry. All the information necessary to check this possible solution is posted. Nick is right; speaker wires are not necessary for this phenomenon, it's all about antenna properties, without the wires the speaker may act as an antenna on it's own. I will refrain from anymore comments on this thread.
george

would you reconsider George? I for one was finding your thesis both interesting and informative. Plus I confess I was rather hoping that a right old ding dong was going to develop.........
SBD

Gentlemen all

Did anyone establish if the irritating whine was actually coming from the speakers?

brianh

Nope!
Bruce Caldwell

James B'ham WROTE:

<< except it's not my ears!!! (doctor) >>

Why not use your stethoscope to locate said noise?

An irritating wine - sounds like something some food and drink TV conessewer would have problems with ....

I'll get me coat .... :o))

John McFeely

Brianh,
I work on RAF Lakenheath (a USAF base). I have all the equipment necessary to demonstrate exactly this principal. I invite you, when your able to come down, to do a few experiments, and I'll demonstrate this to you.
While your here I'll buy lunch, and give you a tour of the base. You'll also get to see some F-15 fighters close up, and if you'd like I can show you some of the RADAR, Radio, and Navigational systems used by aircraft.
And if you like, I could give you a quick course on antenna radiation theory, and this is not meant to be sarcastic. When I finished my masters in electronic engineering, my knowledge of RF transmission theory was very weak, but that was 21 years ago. Since then I've learned a lot, and of course this is my specialty now.
Arguing theories on email is pretty pointless, especially when we can make a social event of it, and have fun. You can check out my MGF too.
George

Actually the signal strength from an unprotected AM source could quite easily generate the required signal to power a speaker. It may be worth checking that the suppression is actually working properly on your car.

I would guess it has nothing to do with the speakers so this discussion is quite pointless.

>Isn't is strange how quickly this BBS gets abusive - still it's better than road rage.

The BBS does not get abusive, some of the contributers do it all by themselves.

>An irritating wine

I think this may be down to some contributers also :-)
Tony Smith

I have absolutely no technical qualifications or experience but can assure that my speakers have on occasion started to whine even when the system is off. The sound even seems to change pitch as the revs climb and I change gear.

After I upgraded the system this stopped.

Cheers

Ralph
Ralph

On a trip to Italy in '97 the door speakers in my *F* started to make some very strange noises, so much so that I was very worried. However on the way back they stopped and it never occured again!

BTW these strange noises only occured if the radio or tape were on but they became so loud they actually drowned the music.

Do you think it was Richard Dimbledy's spagheti tree causing it?

Seriously these noises did occur and have never occred again even though I have been to that area again and still have and use the tapes.

Ted
Ted Newman

So does this mean there isn't going to be a fight? You're all very nice to each other here aren't you?

Where's Lakenheath? Don't give a monkies 'bout your F's but George's offer sounds like a right good'un.
SBD

Suffolk not too far from Ipswich.

Ted
Ted Newman

George

I'll take you up on that offer so long as we can avoid EM theory.

Several years ago I sold GPU's to the RAF and so spent a bit of time around Tornado's, Jaguars and the odd Harrier plus, of course, Rapier.

brianh

Brianh,
My email is listed here why don't you send me your email and we can make arrangements, and I promise to skip the EM theory.
george

and avoiding EM theory (whatever the bollocks that is) will give you time to nip round the back of the bike shed for a bit of heavy petting eh?

God do you lot really have to be that nice to each other? You couldn't conduct a decent heated debate in a sauna. I suspect that George may well be talking utter poo as well as I can't imagine that in the current world situation the USAF is going to let some limey geek wander round one of their airbases with his camp mates.

Damn it I'm going off to kick the dog and ravish a virgin.
SBD

You sure you got that last bit round the right way SBD?
Jim

Right back to cars.

Speakers could well be a red herring here, but I've had experiecnce of this type of problem in several cars.

I have found that some car stereo's in some cars can give this type of engine speed related whine.

I am a mere Building Services Engineer (fancy title for an electrician who has done a little more part time study and now also dabbles in plumbing for a living), but...

I have found that such whines only occur when there is a stereo fitted so I would guess that even when off there is some amplification at play here.

First off try removing the radio and disconnecting it (don't forget about the security code). If it goes away you've found the whine.

Assuming it is the radio / speakers it could be the alternator or the HT leads / ignigtion system. The HT leads would be a good place to start (there is little else to the MG ignition system is there?)

I would suggest that you seek specilaist advice from an alternator rebuilder if it this is suspected as somthing must have failed so fitting after market suppressors may be a waste for time.

Incidentally the electronis theroists above seam to ignore the power of the spark from the ignigtion system, the neighbours lawn mover plays havoc with my TV and one of my sisters friends car had such duff HT leads you could tell it was her coming because the TV picture would be affected when she was about half a mile away. Then there are police radios and mobile phones....

Anyway theres my advice, trusting that all surplus females have been removed from the car of course!
Andrew

LOL Jim, any port in a storm!
SBD

Well, I'd take up Geoges offer !
BTW, I like 5 live (listening to it). Trouble is, it's all crackly and nasty on MW. Radio 1 and general FM stations are fine.
In my ignorant state, I was thinking of replacing the HT leads with some hign perfomance magnecor ones from B&G.
Could any of you guys advise me if this is a sensible thing to do from a static/interferance/crackly reception point of view ?

Cheers

Kieren
Kieren Gibson

Hi all,

at first I read James message the other week with some *grin*.

Now today I were after another noise in my car and had no radio on for several miles.

And don't laugh... I hear a noise like described also in my car.
Slight high frequency whisper like from a TV set HV transformer.
It's of course not from rear speakers, cause I haven't any and the radio was off.
Theory about the ECU clock generator sounds strange for me. It isn't that high grade electronics and the vakuum sensor is the only mechanical part inside. 16MHZ crystal only
http://www.mgf-net.de/mems1.9/dk_cp_5712.jpg

At last I switched on the CD player, pushed the accelerator (SP 'inside') and got rid of this noise.

... but still wondering what it relates to.

Cheers
Dieter
Dieter Koennecke

Thanks guys, I enjoyed immensly the theoretical ding dong. As a qualified Electrical, Mechanical and Aeronautics Engineer - FRAeS et al I found it hilarious! Much more fun than when I had to stay awake in tedious HF Electronics modules!

All he wanted to know was how to stop the noise - I can help there, my brother in law's an ENT Surgeon...

I'm off to bed now to dream about megahertz and count wiggly amps, night night zzzzzzzzzz!
Ian

Ian

Glad to hear you are so well qualified! And glad to see you are great at 'taking the piss'. Pity you aint so great at offering constructive advice!

Ted
Ted Newman

I did offer advice - as long ago as the 28th October but that didn't help.

IMHO the other likely cause is induced noise due to 'radio frequency' interference so expertly debated above. Either from the car electrics - probably well screened anyway but a good Car Audio supplier might help pinpoint source or suggest smoothing power leads et al to head unit.You could try switching engine on/off, fan on/off/ fuel pump on/off to isolate source - usually motors or generators and ign ccts.

Mains transformers/substations cause noise but if heard it would be a low freq hum (50hz). The other source is RF interference from Radio, TV, mobile phones/transmitters? Radar / Radio Direction Finder beacons from airport using airport transfers tunbridge wellss/military establishments/airfields This is considerably more difficult although as suggested above changing the length of the (speaker) wire (antenna) might help. Questions to solve this interference would be related to noise changes with geography - i.e. driving past the beacons at Blackpool airport causes interference on a car I had. A bicycle computer stops and a training heart monitor stops working too - RF noise swamping the tramsmitters on both. All are OK when signal is passed. A TV we used to have fickered when the Radar was switched on too... So listening for noise changes driving around with a map might pinpoint possible sources.

My mobile causes interference if I put it in the cubbyhole below the radio - but that is clicking noise (digital transmission). Is there anything in the car - PC, pager, handheld devices etc?

If the sound is constant thats harder to fix - what he needs at that point is an Radio Frequency boffin as above with some time and test gear like an oscilloscope to measure frequencies and amplitude of the noise. From then on its noise suppression as expertly discussed elsewhere in this thread.

Good luck

Ian
Ian

OK Thanks Ian.

I suppose you could do like me and spend the best part of fifty years working with extreme noise and no ear defenders (didn't exist back in my RAF days) and riding motorbikes without ear plugs then the Tinitus will disguise any funny whines that the *F* may make.

In fact if I get enough funny whines they might even turn into 'white noise'.

Ted
Ted Newman

This thread was discussed between 16/10/2001 and 06/11/2001

MG MGF Technical index

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