Before you guys kill me for making another idle issue post, I have been searching for weeks and have tried about everything I can find.
So anyway I've got an 89 CRX Si 1.6 just bought it a few weeks ago I am new to this Honda thing correct me if I'm wrong about anything here. I bought it with with an idle problem figuring I would be able to fix it. Well 3 weeks later here I am, when I got it it was idling around 3-4K and hunting for an idle. I found a crack in the radiator so I replaced the radiator. Yes I bled the coolant (multiple times now) At the same time I also installed a new Thermostat, IACV and throttle body gasket. This did seem to help a lot as the car dose idle normally *sometimes* (around 600 rpm). However sometimes I will be driving and the idle will just decide to come up around 2k, but it's not always 2k sometimes it's 1500 sometimes 1800, 2500, etc. but when it does this it's still a steady idle it doesn't hunt for an idle at all. I have also sprayed every vac line I can find and every gasket I can find down with both starting fluid and brake cleaner in search of a vac leak but have found nothing. Please help out a new Honda owner before I drive this thing into a wall haha

 

I'm sorry if my information is wrong on the single cam but I believe that engine uses a FITV under the throttle body. Take your intake pipe off of the throttle body and there should be two holes in there before the throttle plate. While idling high place a finger over the lower hole sealing it off. If the idle drops and it runs normally than your FITV is acting up. They can be taken apart and fixed pretty easily.

-Amp

 

I have looked into that, however my FITV isnt located on the throttle body, it's on the back side of the intake manifold. It also doesn't have the white plastic peice in it like most models I have seen so there is no adjustment. It just has a small spring inside of it. I'll try to attach a pic

 

check your ground wires.
ONe is on the thermostat housing
one is from the cylinder head bolt to the chassis
And one from the tranny bracket to the chassis,
one from battery negative to chassis

The o.e ground goes from the tranny bracket to chassis to the battery.


Other than that, check your timing, plugs, wires, dizzy cap and rotor.

 

have you set base idle per the manual with the IACV/EACV disconnected?

 

What would spraying the vacuum lines do to identify a leak? They are under vacuum after all.

 

yea its to find a leak
if you spray them and the idle changes then its because they sucked in the spray and there leaking
but if you spray them and nothing happens to the idle then that means there sealed and there working as they should

 

Only thing I can think of is the throttle cable might be getting stuck sometimes. When it does it again, try pulling up on the gas pedal. If idle settles, your issue is either the cable or somewhere in the throttle area.

 

I have it solved, it's the color of your car.

Kidding aside, I had this happen to my 88. The throttle cable was slightly frayed so it would get hung up sometimes instead of releasing as it should right at the TB. I would just blip the throttle and it would fix the problem until I got a new cable installed.

 

Ill definitely look into this. already did plugs but how do you check timing on these cars? Again I'm a domestic car guy so I'm used to just pointing a timing light at the balancer haha. 8"

i dont think its a problem with the throttle getting hung up. When it does it I have tried stabbing the gas multiple times and nothing changes

 

mind taking a pic of your engine bay
so i can see the big picture
engine intake the way the lines are run

where do you live? if your close i can fix your idle problem no problem
but if your too far away then pic per pic it is

 

When the car is idling higher than normal slip your foot under the gas pedal and lift it towards you.
Does the idle drop and stay down after you remove your foot?

 

I'm from eastern Iowa, here's some pics to start with

 

Make sure TPS is set right, idle screw is closed. Throttle cable screw is lowered so the TB can close almost all the way.

 

This is the road I would take:

disconnect throttle cable, does the car idle correctly?
plug the IACV fresh air port on the filter side of the throttle plate with your finger. does the car idle correctly?
pinch off every vacuum line except MAP if yours has a firewall mounted MAP. does the car idle correctly?

based on these answers, you should narrow down what you're looking for

checking base timing on these cars is the same, there is a pointer on the timing belt cover and two lines on the crank pulley. same as any domestic I've come across. use a timing light and time it to 16 deg BTDC (off the top of my head, check specs on the underhood sticker or service manual).

the tricky thing in your situation is the car needs to be idling for you to check timing

 

Try main relay, they also control the air idle control valve

 

You have to check every possible air entry port. A big one most people forget is the Brake booster. The gasket between the Booster & Master cylinder is actually a vacuum seal. If this seal goes bad, you will have a vacuum leak. Especially when you push on the pedal. The booster could also leak from other areas like the footwell (though you would hear hissing inside the cabin. To rule out the booster, simply disconnect it's vacuum line and plug it with your thumb. If idle goes normal, you know it's the booster or booster/master seal.

BTW: The 89 Si has no FITV. Instead it has a fast idle solenoid (the device on the back of the manifold). It only opens up at very cold temperatures. If you think it's opening, un-plug it's 2-pin connector under the manifold and see if changes. If you think it's o-ring is leaking, spray some carb cleaner on the seam to see idle changes. To see if the valve is bad and simply letting air in, disconnect the fresh air tube coming from the throttle body and plug it with your thumb. Just be careful removing that tube. It is long discontinued.

- Manifold gasket
- Injector-to-manifold seals
- vacuum lines (3 for the Map sensor, 2 Purge Solenoid, 1 Charcoal Canister, 1 Dash Pot, 1 Fuel Pressure Regulator, 1 PCV Valve, 2 brake booster)
- Idle Valve gasket
- IAT gasket
- Also Check your PCV Valve isn't hollowed out or something weird
- Cracked Intake Manifold

If all else fails, try a different PM6 ECU.

To me this is kinda sounding like a Throttle Body or problem. Like something is actually opening up the throttle plate. IF the ECU detects zero throttle, it will normally cut fuel over 1100rpm (this is why people with vacuum leaks have the idle bouncing around. Could also be a distributor or wiring problem where the ECU can't detect rpm correctly. Or a coolant temp sensor problem. If the ECU thinks the coolant is cold, it will keep a high idle in "warm up" mode.

 

Watching this thread closely. I also have a 89 crx Si that idles around 1500 rpm and I can't figure out why. There are some good troubleshooting tips on here that I will definitely be looking into.

 

yea man all your vacume lines are connected where they sopposed to
im just going to add to all the things everyone else has been saying

one other thing to do is check for air leaks
if you have a air leak the car will idle higher
you can do this with water and a spray bottle
so with the car on

just spray around the throttle body gasket and vacume lines
also your main intake gasket at the head and if you here the idle change and it lowers
then you just replace whatever gasket or line you were spraying the water on

eastern iowa is about 4 hours away from nebraska its up to you if youd like to make the trip
i could meet you in omaha ne also that way you would only have to drive 3 hours ish
haha im interested in finding out whats wrong with this thing

 

My 89 si does it's own weird thing. When I first start it cold, it wants to idle at 2k. As it warms up, it slowly drops to normal.

I've checked and replaced everything. Even rebuilt the entire top end. The ecu is just forcing the high idle. If I let the clutch out, the car actually accelerates to 2k (I don't think a vacuum leak will do that). The thing that really pisses me off is I've even swapped ECUs with no change. Guess it's time to start checking the resistance of wiring or something.