hey guys-im new to the board but hope someone might be having the same problem as i. here goes--my rig has developed afluttering sound which seems to come from the left side of my motor-truck also is louder upon acceleration i checked the exhaust and it seems ok--no VISIBLE leaks. i have owned 3 other 4 runners and never heard this before! i was told they all sound like that!!--YEAH RIGHT!! any body have any ideas?

 

You say developed, so I figure this isnt something that has always been there. Any loss of power associated with the sound? Any recent check engine lights? Any recent work done on the vehicle?

 

I think you got what I got. I have no idea what it is...Pinging?

 

it seems like an exhaust leak. but since u dont see any visible leaks i cant honestly say what it is. i would say maybe u could try replacing the gaskets on the exhaust manifolds.
i had a fluttering noise after i installed my headers and i found that i blew the gasket, so i replaced it and the sound went away.

-Casey

 

That's why I asked about the loss of power. There should be a slight loss of power associated with an exhaust leak pre O2 sensor.