Do I have a slight misfire? Or? Video included

Wow that flywheel clutch area sure sounds like a bag of marbles. The engine itself doesn't sound bad, its hard to say revving in neutral without a load on the motor. Could have a light miss...

 

Try cleaning the airflow meter, with afm spray. Also, start keeping an eye on the wires to the crank trigger.

 

Also burnt headers make the engine backfire because the 02 sensor mixture is all bamboozled. So, since you have a capristo exhaust, it may be hard to hear but try to have a close listen when cold to ascertain..

 

It could just be the kluber grease leaked out of the dual mass flywheel, or noisy bearings. That death rattle on shutdown seem to lean more towards flywheel. It probably wont fall apart on you but it will surely sound rough.

Regarding headers, Listen for a tapping raspy exhaust leak sound, or smoke test that system and see if you have any gasket/header leaks. feel around the clamshells /all joints /bypass pipe/cat joints while the car is cold.

This is important to take care of but it may not even be your headers. Doesn't hurt to check!

 

Or the oxy sensors could just need replacment. Doesnt need to be a bad header causing it.

The death rattle is the dual mass flywheel.

 

That rattle sounds like the bypass valve. When its running get a screw driver and push on the actustor arm and see if the noise goes away.

Otherwise id say its clutch related.

 

Agree with all comments here, it could reallly be many things, 02 sensor, vaccum leak, intake boot leaks post maf etc. Fuel filter, injectors, cam sensors connections. Lets list them all.

Tie the bypass open with something and go for a ride. Give it a good italian tune up 8550 rpm shifts. See how she runs after that. What year is this bad boy? If its a 95 disconnect both 02 sensors and see if that smooths her out Per Dave Helms.

Pull the plugs, see how they look and pay attention to #2 and #7.

Internet diagnosis is fun!

 

The flywheel may need to just be taken apart cleaned regreased and put back together.

Of course thats not in the ferrari workshop manual

 

On the 95 you can see the bypass easily, it's sticking out between the airboxs via a hole in the exhaust heat shield. People use chicken wire to hold the valve in an open state.

 

I wouldn't advise opening the valve for anything other than eliminating the buzzing sound so you can diagnose your other potential issue. I'm a fan of the working bypass valve and think it adds to the character of the 355.

 

Tying the valve open temporarily is a great diagnostic way of eliminating the valve as a source of noise vs clutch area.

Since you have a 95 unplug the 02 sensors I think they are located somewhere on the inside shocktower for that model. If this makes the engine smooth then your problem lies with either a defective 02 sensors, or an exhaust leak which is throwing the mix off.


Quick and easy stuff here. If that doesn't work pull plugs and inspect ignition system next.

 

First test to see if opening it removes your noise.

If so you could tie it open and.go.for a.drive and see if you feel the flutter.

If its still there youll know.

If the noise stays its not thst if it gies away it is that.
Just quick trouble shooting.

I just used a long flat head and pushed on the actuating arm to actuate it noise went away. So I found my culprit quickly.

Or use a Vaccum pump but screw driver was faster.

I was working on my car this winter, I found my bypass had been wired open, so I removed the wire.
First time starting it after the work I did on the exhaust kit was vibrating and just making damn noise from the rear exhaust area, I remembered that stupid valve and opened it up noise went away.

Race cars don't have the bypass why must we suffer haha

 

I go with the clutch springs, flywheel needs regressing. Just my personal opinion.

 

Rattling cats.

http://www.ferrarichat.com/forum/348-355-sponsored-bradan/419762-what-noise-any-help-appreciated-3.html

 

That rattle is loud enough it shouldn't be to hard to find, Put a stethoscope on the pumkin and the cats and try what PHROGS said

 

I don't hear a misfire but may be more noticeable under load? Seems to idle pretty smooth. My 95 with the same exhaust setup seems a bit more choppy at idle.

https://www.youtube.com/watch?v=tYbdJLfPxfw

 

Plug a obd in and see if your fuel trims are out. Maybe you will see 1 bank running rich or at the vary least it may have logged a pending code.