Strange new flutterung sound from f 355 when letting off the throttle?!

How many miles on your car? Not to scare you, but it could be a cat starting to break apart? Are you still running the OEM cats? Or maybe one of the headers starting to go?

I had strange sounds but also a check engine light in my old 360, so I knew something was up...- in the 360 there is a pre-cat (mini cat close to the header- terrible design but only there to appease the tree huggers to reduce emissions for the first couple of minutes after a cold start before the main cats are fully warmed up)..the pre-cat let loose on one side, and went downstream to the main cat on that side of the car and took that out as well.

With exhaust in these cars it can be lots of things...headers, cats, bypass valve. I hate to say it, but if you notice it and it's bothering you there's nothing you can do other than take it in to have the mechanic check it out. Often with Ferraris if you catch things soon enough you can save a lot of money (vs. my father's method with his cars in the 70's and 80's- where there was a strange sound the radio just went up louder ) I think his '76 buick Lesabre (105hp V6!) made strange noises straight from the factory, but I digress...

 

I've been reading this section for 8+ years and never heard of the fluttering you're experiencing... Sorry can't be of any help. Maybe your bypass valve hinge is on the fritz or more likely just needs to be properly lubed with something other than WD.

 

In my opinion I think it is a common issue and isn't a problem, many cars do this when the mixture is a tad rich. If your car is a 5.2 you could check functionality of 4 02 sensors, otherwise 2 on 2.7, maf, throttle body balance, fuel system integrity (pressure, injector flow etc) and verify cam timing if the issue persists. The engine should NOT run roughly. If so check for a mis fire.

I have driven a half dozen 355s they all seem to exhibit some burble from time to time under certain super light throttle descending from high rpm, burble etc whatever you want to call it. More pronounced if there is an aftermarket exhaust setup. These aren't mercedes motors that sound perfectly smooth at all times in my opinion, especially a 2.7 at idle.

Also, you can test and tie the bypass valve open temporarily to eliminate it as a cause .

 

Perhaps you should see if there is an exhaust leak. That would screw all your mixture up and make it sound like a dump truck. lol.

 

Before you re-set anything you may want any codes or info to be stored in there for diagnosis if it doesn't clear up? At least it was that way in my 360, although the 360 may have a more sophisticated CEL/parameter memory (my mechanic would hook up the "SD" Ferrari computer to the car). I'm sorry to keep bringing up the 360- I had it for 6 years so I'm just more familiar with that model, only had my 355 for a few months, and of that only a few weeks of driving time. Are you north NJ? (just curious if I may have met you at the Chatham C&C events..)

 

I had a similar sound issue and it was caused by a left cat which come loose after a broken exhaust clamp,

 

Monitor your fuel trims real time while driving.

If your obd tool can't do this, get one that does.

$50 - $100 in conjunction with an iphone/android device.

 

Don't know what the noise it, but for future reference, WD-40 is not a lubricant. Unless you believe your valve to have rust, you should use a proper lubricant.

 

This was one of the symptoms of the only time my 355 has let me down.

Every time I came off the accelerator there would be a strange fluttering sound from behind, which ultimately became like a "stuck" throttle.
It was almost like the car was on cruise control.
ie. I'd lift off the gas but the car would carry on at the same power setting.
Yes, I did crap myself going into a couple of tight corners when it first happened...

My mechanic found that one side of the throttle attachments had come off(?).
Once it was re-attached and everything adjusted it was good as new.

Terrible explanation I know but hopefully the more mechanically minded will know what I mean.

 

Brian is coming over tomorrow to change his gear oil. We will take it out for a drive and see if I can hear what he hears. The throttle bell crank is problematic and maybe that is what he is experiencing.