I purchased an 03 S2000 in August with 64k miles. Completely stock. It has been running flawlessly since I've purchased it.

However, recently (over the past few days) I have noticed a rattle in low RPMs, it could also be at high RPMs but it is suttle and gets drawn out with the overall engine noise.

It is not affecting the engine performance, but I am noticing VTEC issues (going to whack the map sensor and give that a shot, separate issue I presume)

Here is the video:
[media]http://www.youtube.com/watch?v=3x2TVcA6DZE [/media]

What could it be ? Any ideas? I am going to do an oil change tomorrow, anything I should look for while I am at it ?

 

I suspect that it is a timing chain auto tensioner (TCT).

What are your VTEC problems?

 

It seems to be inconsistent VTEC engagement, notice it especially in 1st, but other gears too. Sometimes engages normally around 6k, other times 8k, or sometimes never.

 

after doing some more research about the TCT, I'm 99% sure that is what is causing the sound.

Thanks a lot for pointing me in the right direction.

 

Vtec crossover will happen only if all the sensors that belong to that system are working correctly. (i.e. oil pressure sensor, speedo sensor etc.)

If one of them is failing, you will experiment vtec issues.

 

Intermittent vtec issues is usually map sensor. Gentle map whack will likely fix it.

 

make sure your oil levels are within the recommended range, and keep in mind the error on the dipstick readings (use the lower of the two readings).

 

I do think I clearly hear the TCT noise there also.

 

Sounds like TCT to me.

Have the worm gear sand blasted