Rattle/Scratching Noise during hard acceleration
Thread Starter
Instructor
Joined: Dec 2006
Posts: 155
Likes: 0
From: SJ CA
Rattle/Scratching Noise during hard acceleration
I have a 2001 M6 CPE. Every time I accelerate hard (above 4000 rpm) I hear a rattle/scratching noise coming from under the car. It's not the normal rattle noise heard when accelerating from too low of an rpm. Only when I punch on it with high revs. It's been doing it for years. Could it be the clutch, broken ceramic in cats, torque tube? Anyone have any ideas?
Le Mans Master
Joined: Feb 2006
Posts: 5,267
Likes: 40
From: Phoenix AZ
Ill take a stab 
Does it burn oil like my 01?
The early ones do....I dont know the VIN cutoff for the oil rings though.
My guess is that it could be pinging under load.
I see you have some mods. Maybe see if you are getting alot of knock retard.
Could have carbon buildup or just be a little lean......thats assuming the noise is coming from the engine and not some exhaust spring or something.
May try some seafoam, its only 8 bucks.
Does it burn oil like my 01?
The early ones do....I dont know the VIN cutoff for the oil rings though.
My guess is that it could be pinging under load.
I see you have some mods. Maybe see if you are getting alot of knock retard.
Could have carbon buildup or just be a little lean......thats assuming the noise is coming from the engine and not some exhaust spring or something.
May try some seafoam, its only 8 bucks.
Thread Starter
Instructor
Joined: Dec 2006
Posts: 155
Likes: 0
From: SJ CA
Ill take a stab
Does it burn oil like my 01?
The early ones do....I dont know the VIN cutoff for the oil rings though.
My guess is that it could be pinging under load.
I see you have some mods. Maybe see if you are getting alot of knock retard.
Could have carbon buildup or just be a little lean......thats assuming the noise is coming from the engine and not some exhaust spring or something.
May try some seafoam, its only 8 bucks.
Does it burn oil like my 01?
The early ones do....I dont know the VIN cutoff for the oil rings though.
My guess is that it could be pinging under load.
I see you have some mods. Maybe see if you are getting alot of knock retard.
Could have carbon buildup or just be a little lean......thats assuming the noise is coming from the engine and not some exhaust spring or something.
May try some seafoam, its only 8 bucks.
Thread Starter
Instructor
Joined: Dec 2006
Posts: 155
Likes: 0
From: SJ CA
I was lightly pounding on my pipes just aft of the cats at the o2 sensors and I hear something rattling in there. I think there might be a chunk of the cat's ceramic in there. Do cats normally wear out and break even though they've never been crushed on a speed bump or something?
Instructor
Joined: Oct 2005
Posts: 158
Likes: 0
From: Ft. Myers FL
Just a guess but if it is only doing it on acceleration and is getting a lean code I would think it's detonating up top from too much timing or not enough fuel. Get it on a scanner and see if you are getting knock retard.
