Puffing/chugging sound when warmed up

[jcrun]

Just got a 2004 LX470 w/275K. There’s a puffing/chugging sound (not ticking or knocking) that occurs only at idle and only after the engine warms up. It seems to be coming from the rear upper portion of the engine but can’t pinpoint further. Loud enough to hear while sitting in the vehicle, but not scary loud. As soon as the engine comes off low idle (even a tiny bit) it stops. Thanks in advance!

 

[Mike NXP]

Will probably need to hear audio. Any check engine lights or performance issues when driving? These engines certainly aren't the most quiet out there so it may be normal.

May not be happening when"cold" because rpms are a bit higher and then when it settles down to the idle rpms you hear it more.

 

[jcrun]

No check engine light, but maybe a tiny bit of a rough idle. Not sure though because I’m still learning the car. The engine is otherwise exceptionally quiet.

 

[Mike NXP]

No check engine light, but maybe a tiny bit of a rough idle. Not sure though because I’m still learning the car. The engine is otherwise exceptionally quiet.

Can you get some audio posted or video?

 

[jcrun]

LX 470 Engine Noise Youtube

 

[Mike NXP]

LX 470 Engine Noise Youtube

Hmmm interesting.... I would remove that engine cover and get a stethoscope to try and probe around and narrow it down. It doesn't really sound like it's internal engine noise.

 

[jcrun]

Hmmm interesting.... I would remove that engine cover and get a stethoscope to try and probe around and narrow it down. It doesn't really sound like it's internal engine noise.

Agreed. It sounds like something pumping air and it sounds like it’s coming from the block valley toward the rear. Same volume from either side of the engine. Anyway, I’ll report back if I figure it out.

 

[jcrun]

SOLVED (I think): Replaced the spark plugs today and #8 ignition coil was coated in fuel and oil and the plug was VERY loose. Not even finger tight.
Put in a new plug, torqued appropriately, and the sound appears to be gone.

 

[thebeedeegee]

Man, glad you caught that. You will find a thread warning against this very issue. I tend to check my plugs about every oil change out of paranoia now.

 

[94SRUNNER]

^^^^ ditto

I check the spark plug torque a couple times a year as I have experience plugs loosening over time.