hello everyone, here I am again asking for expertise.

So recently I've been working on my s2k, disasembelled the entire head assembly had it rebuild, had a few issues like a dink on the piston which I was able to polish out very easy, damaged head after getting it rebuilt and was later repaired which looked awesome. Anyway after I rebuilt the head. I turned it over and it started! I was happy as heck. However yes there is a however, my car starting to rev up and down from 3k to 1k approximately. I was making sure I can bleed the radiator for a while which I believe can be the cause of that issue. Any ideas? I did get a check engine light but it did not flash which makes me think it's not the misfire codes I was getting before I rebuilt the head.

let me know what you think I would appreciate the input as I would love to have my s2000 back on the road. The battery died from turning
it off and on a few times and having it sit on carboad for allost
three months and it was old.

thanks

I will today when I get a chance after work. A vacuum leak could be anywhere? What do you mean by hourly? I forgot to mention that I did forget to bolt back one bolt on the intake manifold would that be a possibility?

I can’t give you very specific reasons why this happens but I have experienced it occasionally when performing IACV cleans. Idle just bounces to 3k and down over and over. Has happened to me at least twice and I didn’t have any vacuum leaks.

What has solved it for me is taking it on a short highway highway drive and ripping through the first three gears. Once I roll off the highway things seem to be back to normal. Can’t explain it.

Sorry I don’t have more precise information.

https://www.s2ki.com/forums/s2000-un...issue-1172549/

Does your car have an IACV? (00-05)

Thanks everyone