Exhaust Rattle -or- Detonation?

[AlexIX]

I just bought a Black 2001 Mustang GT about 2 weeks ago. And I've been noticing a fairly loud rattle sound coming from what seems to be the exhaust near the front end of the car... I'll give you some facts to when I hear the rattle:

• Only occurs while the engine is cold. (Normally first 10 minutes after startup.)
• Only occurs while in the 3100 - 3400 RPM band.
• Occurs under both heavy and light acceleration.
• Occurs in all forward gears.
• FORD did not detect anything wrong with the exhaust and believes it may be detonation.
• FORD recommended to try using a high octane to solve any detonation issues, I've switched to 91 octane (Highest in my area). Found no change.

Any ideas to what could be causing this rattle? Do you think it is detonation? Is detonation a serious problem that should be looked at immedeatly?


Thanks guys!

 

[Kilgore Trout]

Its the Death Rattle... Do a search of this forum for the phrase.

 

[Mike97gt]

i agree with kilgore, it's not a big deal but you should not be getting on it untill it's warmed up.

 

[DocG]

If it only does it cold, doubt its detonation and would probably not detonate under light load....but there's always the exception to the rule. Mine rattles too, but it does it hot or cold, even seems to rattle a little after letting off the gas.

You could always check for something loose, heat shield on the exhaust, there's a cover on the tranny where the clutch cable attaches that can rattle, brake shield. Most likely what Kilgore said though.

 

[AlexIX]

It appears I might have a more serious case of the "Death Rattle".

Sometimes I'll still get that rattle even when the car has completely warmed up at exactly 3200 RPM under light or even heavy load. Sometimes when changing gears hard at high RPM I'll hear the same rattle too. It doesn't sound healthy at all.

Should I keep taking it to FORD?
Or will it always make this rattle no matter what I do?

 

[sgarlic]

Remove a variable from the equation.

Swap the stock midpipe back on, and take it for a drive. If it goes away, it's exhaust. If not, could be detonation.

 

[AlexIX]

Remove a variable from the equation.

Swap the stock midpipe back on, and take it for a drive. If it goes away, it's exhaust. If not, could be detonation.

Yeah... I need to update my sig. Thats from my old V6. My GT is 100% stock.