Coolant Bypass, high idling issue

[Freshnicity]

So i did the coolant bypass on my 92 ST, all went well, except now its idling high, like almost 2krpm's high. And when im driving it, and put it in nuetral while the cars moving, the idle shoots up and down from 1k-2krpms, then when i come to a full stop, it stops at 2krpms.

How do i fix this stupid issue?

http://www.ultimateresourceguides.c...a-freemods.html

^instructions i followed

[concealer404]

Vaccuum leak or faulty IAC valve.

[Rick89GTS]

Not sure what mod you did (and I'm too lazy to read the link), but check your coolant level. On the ST162 and ST165, if the coolant is too low, the revs will cycle from 1,000 to 2,000 constantly.

[new echo owner]

Doesn't the ST have a 4a-fe? The 4a-fe uses the auxiliary air valve for fast idle and the coolant that circulate it warms it up to close off the passage to drop down to warm idle.

N.E.O.

[damp]

i have the exact same problem on my 90gts, i noticed i put some coolant in the rad, and the rpms stoped bouncing up and down but still revs high. Ill add more today but did you fix the problem on you celica yet so i have an idea of what it is. thx

[Rick89GTS]

^On my Celica it's fine now.
You may have an air pocket in your system. "Burp" the system and it should be OK.