high idle fix

[chrispycrx]

one day i got in my car and it was cold, i started it up and the idle shot up to like 3000-3200rpm and would go down to about 1000-1200rpm when it warmed up. well after about a month or so of putting it off, i finally fixed it.

i checked the iacv and it was still good.
there is another valve body that looks almost like the iacv but it sits under the throttle body but not hooked to it directly. we opened it up and the plastic piece that the plunger sits in was completly unscrewed inside the housing, so we screwed it back in and it went to perfect idle.

i'm posting this b/c i hope to save some people some money from buying a part they might not need. if the idle is that high there's a good posibility that it's not a vacuum leak, check the iacv plunger inside and the other one under the tb.
p.s. i did a b16 obd0 swap into my 91crx si and that problem popped up
also another problem i had was it bogging/sputtering kind of, so i unplugged one of the o2 sensors and it stopped so i gotta replace it and it should fix it

sorry so long but i thought i should share this with everyone

[RED1990CRXJDMSI]

GOOD TO KNOW

[ccssk8ter11]

thanks! i have been having the same problem with a crx!

[95_civic_gsr]

Originally Posted by chrispycrx

p.s. [...] another problem i had was it bogging/sputtering kind of, so i unplugged one of the o2 sensors and it stopped so i gotta replace it and it should fix it

You may want to check to see if the o2 sensors are swapped. The motor will sputter and bogg down when they are swapped. The civic O2 plug plugs directly into the B sensor and then what most people do is run the wires for the A sensor. This is wrong. Let me know if you think you have this problem.

[95_civic_gsr]

Originally Posted by chrispycrx

there is another valve body that looks almost like the iacv but it sits under the throttle body but not hooked to it directly. we opened it up and the plastic piece that the plunger sits in was completly unscrewed inside the housing, so we screwed it back in and it went to perfect idle.

Are you talking about this?
I'm not trying to seal your thread. I showed your thread to a buddy and he needed further explanation. So I thought I'd post up for all.
This is the Fast Idle Valve (FIV):





The opening you need to look at is highlighted in red.



If you see threads in the opening, then you need to screw it back in.



Close up picture of threads.



This is the access door to screw the plunger back in.



You can see the plunger not in its correct position here.




Mine was completely loose so it fell out.




Picture after I screwed the plunger back in. It worked great by using my fingernails to get it started, but for the final turns I had to use a flat blade screwdriver.




The access plate is still off here to let light in on the plunger. But here you can see there are no more threads showing.

[DOHCDX94]

i've done that to mine once or twice haha. hey it works.

[95_civic_gsr]

Most of the FIV fixes I've done stick. Or at least, last 2-3 years. But one valve fix wouldn't last more than a week. So I had to break down and buy a new FIV.

[DOHCDX94]

yea x2..mine only lasts like few weeks.. gay! but oh well only takes a second to fix.

[stjohnscrx]

i never even thought of looking in there for that problem

[drkhrt]

mmm.. i will have to keep that in mind?

[RED1990CRXJDMSI]

MY 1990 CIVIC SI IS DOING THE SAME THING. I HAVE A D16A6 STOCK. THE ONLY THING I' VE DONE TO IT, IS ADD AEM COLD AIR INTAKE WITH A NEW K&N FILTER AND DC SPORT HEADERS. DOSE THE D16A6 HAVE A FIV? AND IF SO WHERE DO I FIIND IT (ON THE MOTOR)? OR IT CALL SOMETHING ELSE?

[95_civic_gsr]

Its below the throttle body. Three 10mm bolts, bolt it to the bottom of the throttle body along with one coolant line.

[mikeyEF]

damn just what i was lookin for... a friend of mine has this problem on his EG civic... thanks crispycrx and other ppl

[RED1990CRXJDMSI]

Originally Posted by 95_civic_gsr

Its below the throttle body. Three 10mm bolts, bolt it to the bottom of the throttle body along with one coolant line.

kool. but this is on a d161a6 motor too? because i can't see it.

[95_civic_gsr]

I saw the D16A6 and thought D16Z6. I don't know much about the 88-91 civics even though I own one. I looked on the intake manifold from a D15B2 Dual Point injection and didn't see one. On my OBD0 B16A there was a FIV but it wasn't connected to the throttle body, however it was under the TB. I don't have a 88-91 D motor with Multi Point Injection to look at.

If its not the FIV then check the IACV (some books call it the EACV) Intake Air Control Valve. I don't know of a simple fix for the IACV except to buy a new one. If you find a cheap fix, PLEASE let me know.
BTW: The IACV is located on the back (firewall) side of the intake manifold/plenum.

Here are some pictures to show location of the FIV on a D16Z6: