What on Earth is a Frequency Valve and why is OK for it to sceam like a banchee?

I think it is a combination of the frequency valve and the Capacitive Discharge module. Both are components of an antiquated CIS injection system used before EFI motronic is invented. It is normal to squeal at high pitch noise when the key is on. Nothing to really worry about.

 

Mondial doesn't have CDI, so it's not that.

Non cat cars don't have a frequency valve, but still squeal if the throttle gap/idle bypass are incorrectly set.

 

could be a loose accessory drive belt ? They can squeal on start-up when the alterntor is under load while the battery voltage stabalises from the start drain.

 

I agree that it does sound like a slipping belt. I've an 87 3.2 and have never had any such banshees in my boot/trunk! I'd try to better pinpoint the source of the sound (at startup) - the possible sources (belts, FI) are well spread around the engine bay so you should be able to narrow it down more.

 

Check to see if it's the old "chirping" exhaust. Mine did that and I thought it was a slipping belt. Exhaust inserts fixed it.

Birdman

 

Take it to a mechanic.

 

Well, I laughed, but I'm not the one with the banshee.

Ken

 

You might not like it but I gave you some good advice in good faith. And moreover, considering you didn't pay me for my advice, and you're not even subscribed I don't know why you're complaining.

Here's why you got good advice:

I'm sure you'd agree that diagnosing a noise "via the medium of mime", by telepathy or worse still, via an internet board is fairly difficult.

If the noise is as bad as you say I would suggest you DO NOT drive the car unless you know FOR SURE what the noise actually is.

I would say that it is not normal for a Mondial to screech like a banshee.

Therefore, if you can't diagnose the car yourself TAKE IT TO A MECHANIC.

Alternatively, you could wait for a load of wild guesses from people on this board (who can't actually hear the sound) by which time maybe your engine might seize one of its cam bearings through oil starvation or something...

 

have you tried unplugging the freq valve to see if the noise goes away?

The frequency valve is basically a later edition the the first generation CIS system to help make corrections to the fuel mixture. The valve gets a signal from the ECM and translates it into a pulse witch fluctuates the input fuel pressure allowing the computer to have slightly more control over the mixture and in tern the emissions. Depending on which system we are talking about it is either mounted directly on the fuel distributor body or inline with the fuel.

That being said I have heard lots of things in my life as a mechanic but never a freq valve squealing like a belt. I guess therre is always a first time for everything but I would make sure you isolate the noise before diagnosing the problem.

Good Luck

 

I have had the same problem, which was diagnosed as the fan belt. When I changed the fan belt the banshee continued but at a slightly different pitch! The answer to the question is that it is not the fan belt but the pulleys. This happens particularly on mondials when they are left standing for a period of time and the only solution is to either replace the pulleys, try and polish them or have them plated. An easy test for this condition is to spray the belt with WD40 before starting up to see if the noise abates.

 

Sorry, But I didn't think the Tech section was supposed to be funny?
I have replaced noisy alt/fan belts in the past onl to have the noise still be there. Yes, a little WD40 is a good way to diagnois the problem.
Good luck, let us know what you find. But like it has been stated, this is tough over the internet.

Rick

 

RF128706 has a good suggestion --- although perhaps the tone of how it was stated might be taken as a bit snied. In general, loud, high-pitched "squeals" are related to mechanical phenomenon and in particular, bearing or rotational mechanism failure. I would not take the chance that it might be something as harmless as a FI component or a fan belt... I would take the car to a competant professional and get it diagnosed properly. It could be a warning indicator of something major about to fail, and if you catch it now, it may save you a lot of heartache and a lot of $$$. But, if you continue to drive the car and try to isolate the problem, you may run out time --- and the bomb may explode...

 

I have a 91' 348. My car does the same thing currently...it only does it when I give it meduim to full gas...if i give it light gas it does not squeel...but if i hit the throttle it makes this high pitch whinning screaming noise and goes away if i soften up on the gas or let off the gas. Mine is going to the mechanic for the 30K soon and I am going to have him look at it. Where is this valve that you speak of and if you disconnect it and drive it so if that is the problem....is it detrimental to the car...I have no cats..

 

I have the exact same problem with my 87 328. It's not exhaust chipring, it's the banshee.

It happens in any gear with medium to full throttle. It starts at about 4500 RPM, gets loud, softens, then picks up again at about 6500 I'd say. It's definitely noticeable.

Same as above, under light acceleration or no acceleration at any RPM, it is not present--only when giving it medium to full throttle.

I had the local, awesome, Ferrari tech (Dave Helms from Scuderia Rampante) have a look at it yesterday. We made some adjustments to the engine mixture (was running lean), and I've got a follow up early next week.

Glad to hear other 3.2 / 3.4 engine owners are having this issue--hopefully we can get it resolved.

I want to post a WAV of it here soon to convey the noise. It's like a loud, very high pitched whistle. I compare it to the way a one of the fancy turbocharged cars sounds with the turbo open--like an MR2 or something. That kind of a constant, high shrill.

A close inspection of the car showed no major issues. Also, the noise was present before and after the major service I had done last year.

Anyone else with this issue?

And, I'm totally confused when you guys say "fan belt." There are a number of belts going on in my 328 3.2L engine bay, but none is a "fan" belt, at least not in the context of a belt that drives a cooling fan. Are you generically referring to an accessory / water pump / alternator belt?

 

A whistle is EXACTLY how I would describe it! I have put posts up here before about it but nobody could troubleshoot it...hopefully we will figure it out this time!

 

Great news, Ron... Thanks for the follow up and those of us with the "whistle" will continue to check the thread for any progress made on your car!

Anyone have the part number / cost for a new frequency valve?

 

Ahhhhh, i had that problem. The mechanic saw that the previous owner put the warm up thingy-ma-bob ?valve? in backwards so it would whistle during warm up.

 

By the way, found the part number.

It's number 121513, "Frequency Valve", #26 in Table 14 in the parts manual. It's called just "Valve" on the Ferrari UK website.

Listed at $317 US! D'oh!

Surely this thing can be cleaned / repaired? (If it is indeed the problem.)
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This "whistle" is not the infamous exhaust whistle sound? A well known problem on the 308, Mondial and 328 series. Easily cured by using stainless steel inserts for the offending exhaust tips. There are a number of old threads on this. The whistle is caused by the perforated metal in the exhaust tips...as the systems get older, and some of the fiberglass packing is lost, the air passing through the perforations can cause a high pitched and shrill whistle sound. Drove me nuts on my 78 308 GTS until I figured out the source. Made some inserts out of stainless steel sheet, about 3.5" by 7", rolled it around a broomstick handle, then carefully inserted into the exhaust tip. Only one was making the noise, and I moved it around to a fixed the bad one. Then went ahead and made three more and to prevent a recurrance from the others.

 

Hey Dave, thanks for the note... Interesting... So effectively, the steel rolls prevent the air coming into contact with the perforations? What is the thickness of the sheet you used? And (of course?) the sheets don't block the exhaust flow at all / significantly?

I might try listening a bit closer to the actual exhaust. I listened today to the freq valve when revving from the throttle body but couldn't really pinpoint the sound.