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Discussion Starter #1
new noise, any help is appreciated. 2000 burban 2wd 5.3l

From outside, muffled tapping, almost like a rattle. Starts about 30 seconds after engine is turned on. Barely noticeable from outside.

Inside engine compartment, muffle tapping in sync with engine.

If you put your ear against the air intake duct, the tapping is loud and distinct.

Service Engine Soon light recently came on and i cleared it with a scanner, hasn't returned. Returned code p1416 "DTC P1416 Secondary Air Injection (AIR) System Bank 2 ". I've checked and everything seems tight.


Don't know if it's related or not, but started hearing this sound after installing a throttle body spacer. Please hold the TBS jokes and the "remove the spacer and see if it goes away" comments.
 

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HAHA you installed a TBS!?!?!?! :kidding: :lol: Kinda weird that it started making the tapping noise after installing it though. I don't think i've ever heard a rattling sound that is related to intake. Can you for sure tell its not coming from the engine itself or are you not sure? You say it takes about 30 seconds so im guessing it has to be related to the engine... I wouldn't worry that a TBS is the cause.
 

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Well i have a feeling you have ran into a rare occasion and will probably have to have a dealership look at it. I wouldnt think anything is being ruined by driving it, it's probably something stupid
 

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Discussion Starter #9
thanks! I hope so! Am I crazy thinking it might be the spacer just because it's the last thing I did?
 

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No you're not crazy, was the hole in the spacer smooth or was there a design machined into it?....maybe it causes the air to do something weird but to me a tapping in the intake is for the most part unheard of. And if it's not making that sound right away when you start it then it cant be your intake because its sucking air the same 30 seconds after you start it as it does 5 seconds after or 2 hours after...It will make the tapping noise parked and at idle right?
 

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If its not too much trouble pull the spacer off and see if the sound goes away. If it is, thats your problem and probably not much to worry about.


I have 500 miles to drive tommarow...:bawl:
 

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Discussion Starter #12
Actually it starts at exactly the same time, every time, and yes at idle. A friend with a book helped me look up a little more. He says it sounds like air popping and is loudest at right where the spacer is. We tightened it up a little more, but not change.

The light error is about the secondary air that is pumped into the manifolds on each side to mix with the exhaust for emissions.

We think that maybe there is a leak somewhere in those lines or vacuum? There seems to be no performance degradation at all.

The spacer is smooth on the inside. I'm thinking that the reason why it starts after a certain time is that a valve somewhere is being shut off and that air induction is closing and the spacer being there now causes some kind of different "play" than what the computer wants to see?
 

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Discussion Starter #14
Unfortunately I'm going to have to find a new set of bolts and nuts to put it back the way it was!
 

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sounds to me like exhaust manifold gasket, donut, or something exhaust related that is leaking. Exhaust leaks can sound like a lifter tap sometimes. Also, a small exhaust leak will minimally effect performance.

For "V" engines; BANK 1 is always on the side of the engine with the number 1 cylinder (odd cylinders), and BANK 2 is always on the side of the engine where the number 2 cylinder (even cylinders) is located
 
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