I have a 2001 with 45k miles. I've noticed a knocking sound as the engine warms up. It lasts only about 3-4 seconds and occurs when the engine goes from fast idle to normal idle. About 2 minutes after initial start. The sound is similar to sounds I've hear on other cars when I've run cheap, low octane fuel and really stomped on the gas. I always run Shell 93 octane in the s2k. Any ideas?
I'm going to jack the car up tomorrow and check for a loose exhaust.
P.S. the car is 100% stock

 

If your oil level is good, then it's either the TCT or the car needs a valve adjustment.

 

Oil is at the top x on the dipstick. Adjusted the valves about 500 miles ago. Car runs strong no ping on hard acceleration. The intakes may be a little on the tight side. Adjusted the intakes to minimum spec .008-.009 and the exhaust to maximum spec closer to .011. I guess I'll be checking them again in the am.

 

Piston slap?

 

That doesn't sound like valve lash (either from your "knocking" description, or the settings).

Given that it's an 01, it may be the dreaded #4 oiling issue, even with a full oil level. Do a search on "oil bolt" for more info on that problem.

It would be worth doing a compression or leakdown test, if you really want to know, but in the end... if it starts doing it at idle, and sounds more like a ticking, it is probably the TCT. You can replace or sand it. If it gets louder and sounds more like rod knock... it is probably piston slap on #4. The comp test should show about 10psi less on cyl 4 if so (what it does at the beginning).

 

A twist to the knocking! I put the car on jack stands and started it up to look for the knocking. No knock! Repeated, let the car cool and restarted and warmed it to three bars, again No knock! Put the car down from the stands. This morning guess what a Knock.

The knock is not truly rhythmic it could be a portion of the car resonating as the rpms vary during warm up. It does this almost every time when warming from a cold start.

Any ideas how to find the offending part??

 

I've been (seemingly) having the same knocking sound and I suspect it's the rod or crank bearing starting to wear out. I'm still trying to find out for sure though. See this thread: https://www.s2ki.com/forums/index.php?showtopic=610862

 

My car doesn't make the sound when the wheels are off the ground. I would think an engine bearing or even a piston slap would occur independent of load on the suspension.