where can i pinpoint the pvc valve on my 1990 civic

I am not good with cars but can you explain to me in simple english where is the pcv vavle located and the use for changing it.

 

To the best of my recollection, on cars with throttle body injection, the
pcv valve is screwed into the top of the intake manifold and requires a 14mm
deep socket to remove it. On cars with multiport injection, the pcv valve
pops into a rubber grommet which is also on the intake manifold.

A factory service manual can be obtained from http://www.helminc.com.
They're a little more expensive than the Haynes or Chilten's manuals but are
highly recommended as they also provide much greater detail specific to each
model and year.

Eric

 

The following shows the breather chamber's parts for a 1990 4-door Civic, auto
transmission:

http://www.hondaautomotiveparts.com/auto/jsp/mws/prddisplay.jsp?inputstate=5&cat
cgry1=Civic&catcgry2=1990&catcgry3=4DR+LX&catcgry4=KA4AT&catcgry5=BREATHER+CHAMB
ER

Maybe look especially for the drawing's part 5, the PCV tube, to find the valve
on your car. The valve is screwed into the intake manifold.

The following has a drawing of a 1990 Honda Concerto system, but the drawing
looks a lot like my 1991 Honda Civic, so maybe it will be helpful, too:
http://www.honda.co.uk/owner/ConcertoManual/62sk301/6-173.pdf . Again, trace the
PCV hose to the valve.

It helps if one has the new PCV valve in hand to compare with what's on the car.

the pcv vavle located and the use for changing it.

 

A properly operating positive crankcase ventilation (PCV) valve will ensure that
unburnt fuel (in the form of fumes) in the engine crankcase goes to the engine
intake for "re-burning." This improves the engine efficiency. It also reduces
the pollution a car spews. It's considered a part of the car's "emissions
control."

The inspection interval for the PCV valve on my 1991 Civic is 60 k miles or 4
years, whichever comes first.

I wasn't paying attention over the years and did not inspect or replace mine
until 140k miles. The valve was full of waxy carbon buildup and was somewhat
corroded in appearance. After I installed the new one, I saw my miles per
gallon of gasoline increase around 20%.