im not sure on a 1990 but on my 93 civic ex 1.6 vtec the PVC valve is on the intake right under the fuel rail
autozone.com
You can find a 1990 Honda Civic SI wiring diagram in the car's owner's manual. You can also check with local auto stores.
Try MOTORLIT.COM
the PVC valve is by the condigulam and to find that you need to eat crap
No iacv on 2007 civic- I looked for it and couldn't find it and called dealer- found out this year model doesn't have one.
Follow the lower radiator hose to the back of the engine and you will find the thermostat housing.
Its on passenger side near the firewall its a screw on hope you find it
Where can you find a diagram for the fuse box on a 1995 Honda civic si?"
There are a number of places on could find a Honda Civic SI available for purchase including Autotrader. You can also find them at your local Honda dealership.
Blown head gasket.
For a photo of the Honda Civic engine, see the Related Link.
One can find the resale price of a 1999 Honda Civic when one goes to the shop of Auto Trader or any dealers of used cars. A 1999 Honda Civic is about $3000.