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Idling issues for 86 crx hf carb

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Idling issues for 86 crx hf carb

Postby hebrewjew » Sat Nov 03, 2012 5:43 pm

I have a 86 Honda Civic CRX HF. Carburetor. Not fuel injection. :yell: First off, where's the FICV (fast idle control valve), IACV (idle air control valve), and PCV filter on a carburetor? Or is there no such thing. :?: I know where they are on fuel injection. I've messed with the Idle Adjusting Screw, and the Throttle Stop Screw. :blah: That helps a lot, but doesn't solve the issue. When I first fire the car up in the day, it will idle 3k-2k. Sometime it's not that cold outside. It will stay that way for the first 5-15 mins, regardless if I drive it (city or highway) or park and warm up. Tap the pedal, then it drops 2k-1k. Then about after 20-45 mins of driving, it idles perfectly 650-1k (obviously hits operating temp). I'll run into the store. Come back 5-20 mins later, car starts idling 3k-2k. Wtf? :evil: It's toasty. It just seems it thinks it's always cold and has to warm up. A lot. For long periods. I've changed the fuel filter, air filter, spark plugs, wires, cap n rotor, oil changed multiple times, seafoam and other additives, d/c battery (to "reset" ecu). No codes have been thrown before or after. Also, cooling fan kicks on when I first turn the car on, engine cold. Why? It supposed to come on at operating temp (and it does).
I've read and read and read manuals, forums, for months. I'm out of ideas. I don't understand carburetors, and I know a lot of people don't either.
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Re: Idling issues for 86 crx hf carb

Postby PHAT87CRX » Mon Nov 05, 2012 2:58 am

No carbed HF expert here, but sounds like the Choke might be sticking, needs adjusted.
A a carb uses the CHOKE to do the stuff the IACV does on injection.
When cold the Choke closes and a Fast Idle Cam and Screw takes over
the Idle Speed setting from the "normal" idle speed screw that sets it when warm.
When warm the Choke opens and the Fast Idle Cam and Screw no longer "overide" the idle speed setting. The carb Choke is a bi-metallic torsion spring that is electronicaly heated. When cold it coils up and closes the choke blade. When it heats up it unwinds and opens the choke.

Seems on all the carbed CRX's the Carb Isolation Plate between the carb and intake manifold is prone to "go bad" and cause vacuum leaks. Vacuum leaks can cause all kinda issues including a too fast idlde. And you have my sympathy dealing with 70 or 80 vacuum hoses on a carbureted model.

PCV Valve, would imagine the PCV Valve is located in the same place,
it's in the top of a sheet metal box that's mounted to the back of the block
up above and towards the passenger side of the oil filter.
It's a bear to get to the PCV Valve from the top and pull it out of the
Oil Mist Sepertion Chamber Box it is stuck into in a rubber grommet.
___________ 1987 CRX Si NH-94M Quartz Silver __________
If it's got wheels or tatas :shock: It's gonna consume time and money
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Re: Idling issues for 86 crx hf carb

Postby hebrewjew » Tue Nov 06, 2012 7:53 pm

I'll take a look, but thank you so much for yer response. What do you think about the cooling fan coming on at a cold start? It didn't happen before, until a couple weeks ago... Is there a manual fan switch of some sort, or...? Thanks again man. :-)b
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Re: Idling issues for 86 crx hf carb

Postby hebrewjew » Thu Nov 29, 2012 7:29 pm

Ok so... it still idles funny and going through a lot of gas. 15mi. costs me half a tank. Yeah. So I'm starting to think yer right about the choke. How might I go about adjusting my choke? My carb is a Keihin 3 bbl. This is my only mode of transportation, and quite frankly, I'm intimidated just looking at the thing. I don't necessarily want to break the choke, and have the car run even worse. I read the factory manual and all it says is align the index marks. The index marks on choke has a green blob of paint, so I'm assuming that it means its set correctly. Do carbs need their chokes adjusted for winter/summer?

I start it 1st thing in the morning, its freezing, and it idles 2k for 5 secs, then 1200. I either let it idle for 10 mins, or just drive off, and either way, it will idle 2k for half hour, 15 miles later. After tapping the pedal a billion times afterwards it'll randomly idles fine 6-800. And my mpg return to normal.

What exactly controls the automatic choke? The alternator? (If so, its charging my battery fine). Vacuum? (I've sprayed carb cleaner everywhere. No leaks. However, on the back of my carb next to the idle mixture screw, there's two vacuum lines. One goes somewhere, and the other is just plugged up with some metal thing in it. The vacuum line is 1-3 in. long, and doesn't go anywhere. Is it supposed to be plugged? Is it suppose to go to the air cleaner unit somehow?

I'm guessing to adjust my choke I have to twist it clockwise or counterclockwise...

Oh and I CANNOT find the PCV valve. There is no metal sheet black box. There's the black charcoal canister and black vacuum box. But no pcv valve. No one can figure out where it is.
Last edited by hebrewjew on Sat Feb 09, 2013 8:35 pm, edited 1 time in total.
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Re: Idling issues for 86 crx hf carb

Postby hebrewjew » Thu Nov 29, 2012 11:49 pm

http://farm8.staticflickr.com/7280/8167730867_3350a505a4_z.jpg Number 13 is the plugged vacuum line I saw.
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Re: Idling issues for 86 crx hf carb

Postby hebrewjew » Mon Dec 03, 2012 8:55 pm

So you were right. I adjusted the choke. Runs perfect. That took forever to figure out, thanks! Now then, the pcv valve. I've searched everywhere. Everyone says its here, or there. No, it is not. Either mine doesn't have one currently or it's not where people say it is. There is no oil mist separation box at the back. No magic black box everyone talks about. WTF. How [potty mouth] hard is it to find it, Jesus Christ. Someone, clue me in.
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Re: Idling issues for 86 crx hf carb

Postby ybor363 » Sat Mar 07, 2015 1:16 pm

On my 87 Honda Civic the PCV is in a small black box on the back of the block. It's covered in some kind of rubber or foam or something. It's just above and to the passenger side right next to the oil filter. It's best done from underneath. There's a large hose on the top, driver side with a press clamp holding it on. The PCV goes from the hose into the box through a rubber grommet. It's a tiny metal check valve about the width of a dime and about an inch or two long & it's tapered. There are two bolts holding the box on. You don't have to take it off to replace the valve but if you want to clean it out there are two screws, one on top, one on bottom. The one on bottom is easy enough to get to, it's right next to the oil filter on the pass side. The top one is a pain in the ass as you have to put an elbow on the socket, then an extension and try to wiggle that elbow around. I gave up after an hour and a half of trying. The top bolt is between the box and the manifold... so make sure you do it while the car is cool lol. Hopefully this helps and isn't too late.
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Re: Idling issues for 86 crx hf carb

Postby ybor363 » Sat Mar 07, 2015 1:19 pm

Also, check your fuel lines. While the engine is running grab the hoses around the connections and wiggle them, you might hear pressure escaping. That's how I found my fuel dump issue. Mine also has some one way valves on the fuel lines and one was turned the wrong way so fuel couldn't return to the tank. That's probably what ruined my lines. There are arrows showing the direction of flow. If two arrows point towards each other you've got a problem.
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Re: Idling issues for 86 crx hf carb

Postby LocalGirl » Tue Oct 18, 2016 3:13 pm

hebrewjew wrote:So you were right. I adjusted the choke. Runs perfect. That took forever to figure out, thanks! Now then, the pcv valve. I've searched everywhere. Everyone says its here, or there. No, it is not. Either mine doesn't have one currently or it's not where people say it is. There is no oil mist separation box at the back. No magic black box everyone talks about. WTF. How [potty mouth] hard is it to find it, Jesus Christ. Someone, clue me in.


I was wondering if you ever found where the PCV valve was located for your CRX? I jus recently joined this forum, and I have a 1986 CRX DX MODEL made in Japan (carb 5 speed) ... Location of my PCV valve is in the hose attached to the valve cover going into the carb air filter housing on right side, might want to check there if you haven"t located it.
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