Honda Civic / Del Sol (1992 - 2000) EG/EH/EJ/EK/EM1 Discussion

Idle Air Control Valve

 
Old 05-16-2019, 09:35 AM
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Default Idle Air Control Valve

Hello all,

On my 96 Civic EX, 4 door AT, I recently got a CEL code P1509, idle air control valve circuit failure with recommendation to replace IACV.

I bought a salvaged throttle body with IACV still attached. Well, my original parts look MUCH better than salvaged, even after cleaning salvaged but not yet cleaning originals.

I could probably reuse the original IACV o-ring but I have a new one so Iíll use new. The salvaged TBís ?TP sensor? connection housing has large chip broken off, and the coolant hose connectors on salvaged IACV are all rusty, compared to original.

That said, since the CEL code recommendation was to replace IACV, Iím considering using salvaged IACV with my original TB...

Thoughts?


Salvaged TB & IACV before cleaning

Salvaged TB & IACV after cleaning

Original TB & IACV before cleaning

Salvaged TB ?TP Sensor? connection housing with large chip broken off

Salvaged IACV (L) with rusty coolant hose connectors vs. original IACV (R)
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Old 05-16-2019, 09:46 AM
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Default Re: Idle Air Control Valve

I think cleaning the original will probably help you better. I've read a while back that the back piece with the 2 philip screws must not be opened as its adjusted from the factory.
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Old 05-16-2019, 09:53 AM
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Default Re: Idle Air Control Valve

Originally Posted by tony_2018 View Post
I think cleaning the original will probably help you better. I've read a while back that the back piece with the 2 philip screws must not be opened as its adjusted from the factory.
Thanks!

I have not and donít plan on opening the back piece with the 2 philip screws on either the original or salvaged, but are you suggesting to just clean the original IACV, instead of replacing it?
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Old 05-16-2019, 09:56 AM
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Default Re: Idle Air Control Valve

You can try. It looked pretty corroded so I suggest you look at your cooling system and make sure its not filled with just water. Seems to be a ongoing debate but I'm more of using coolant than water.
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Old 05-16-2019, 10:21 AM
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Default Re: Idle Air Control Valve

Originally Posted by tony_2018 View Post
filled with just water.
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Old 05-16-2019, 10:26 AM
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Default Re: Idle Air Control Valve

oh ****!!!
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Old 05-16-2019, 12:03 PM
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Default Re: Idle Air Control Valve

Originally Posted by tony_2018 View Post
You can try. It looked pretty corroded so I suggest you look at your cooling system and make sure its not filled with just water. Seems to be a ongoing debate but I'm more of using coolant than water.
Yeah, thatís the salvaged one that looks pretty corroded NOT the original from my car.
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Old 05-16-2019, 12:12 PM
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Default Re: Idle Air Control Valve

Originally Posted by g4384063 View Post
Yeah, thatís the salvaged one that looks pretty corroded NOT the original from my car.
Why not clean it prior to installation rather than risk spreading that cancerous corrosion around the engine?
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Old 05-16-2019, 12:24 PM
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Default Re: Idle Air Control Valve

Originally Posted by muellersfan View Post
Why not clean it prior to installation rather than risk spreading that cancerous corrosion around the engine?
I cleaned it with throttle body cleaner using brush pipe cleaners, toothbrush and rag but it didnít do much on the coolant connections.

What do you recommend?
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Old 05-16-2019, 12:49 PM
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Default Re: Idle Air Control Valve

Originally Posted by g4384063 View Post
I cleaned it with throttle body cleaner using brush pipe cleaners, toothbrush and rag but it didnít do much on the coolant connections.

What do you recommend?

I need to retract my comment. I saw the before pic but missed the after pic.
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Old 05-16-2019, 01:15 PM
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Default Re: Idle Air Control Valve

Originally Posted by muellersfan View Post
I need to retract my comment. I saw the before pic but missed the after pic.
No problem...Iím still looking for a way to clean the rust from the coolant connections better so Iím still open to recommendations.
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Old 05-16-2019, 01:15 PM
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Default Re: Idle Air Control Valve

Originally Posted by g4384063 View Post
No problem...Iím still looking for a way to clean the rust from the coolant connections better so Iím still open to recommendations.
Wire wheel?
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Old 05-16-2019, 10:24 PM
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Default Re: Idle Air Control Valve

I had the same fault on my 98 hatch, ended up being the plunger deal was stuck. after cleaning it and freeing it up, i got an idle system malfunction fault, so i went to the yard and got a diff IACV. hopefully your luck is better than mine
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Old 05-17-2019, 03:53 AM
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Default Re: Idle Air Control Valve

Originally Posted by muellersfan View Post
Wire wheel?
Thanks!

I have wire brushes but NOT wire wheels. The only wheels I have are these...
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Old 05-17-2019, 03:59 AM
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Default Re: Idle Air Control Valve

Originally Posted by bks84 View Post
I had the same fault on my 98 hatch, ended up being the plunger deal was stuck. after cleaning it and freeing it up, i got an idle system malfunction fault, so i went to the yard and got a diff IACV. hopefully your luck is better than mine
Thanks!
Iím confused; you got the same fault before or after cleaning the plunger deal? AND what exactly is the plunger deal??
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Old 05-17-2019, 05:19 AM
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Default Re: Idle Air Control Valve

The code is an electrical fault. The electrical part of the valve can be tested with an ohmmeter. Also make sure the IAC, TPS, and MAP plugs are all on the right parts by checking the wire colors, since the plugs are physically the same.

Plain water is murder on the cooling system. There's no debate about that. The evidence is right here in those pictures.

Do not try to take the electrical part off. In most climates it is not necessary to flow coolant through the IACV, so if your IACV leaks coolant you can bypass it by re-routing the coolant hoses. Heating the valve with coolant does help in very cold weather or cool / damp weather which can cause ice to form inside the valve.
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Old 05-17-2019, 05:32 AM
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Default Re: Idle Air Control Valve

Originally Posted by mk378 View Post
The code is an electrical fault. The electrical part of the valve can be tested with an ohmmeter. Also make sure the IAC, TPS, and MAP plugs are all on the right parts by checking the wire colors, since the plugs are physically the same.

Plain water is murder on the cooling system. There's no debate about that. The evidence is right here in those pictures.

Do not try to take the electrical part off. In most climates it is not necessary to flow coolant through the IACV, so if your IACV leaks coolant you can bypass it by re-routing the coolant hoses. Heating the valve with coolant does help in very cold weather or cool / damp weather which can cause ice to form inside the valve.
Thanks!

Can I use this multimeter to test the electrical part of the valve? If yes, how do I do that?

I donít run plain water in my cooling system. The badly corroded parts are from the salvage yard.

I wasnít planning to take the electrical part off. And FWIW: I am in a hot and humid climate.
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Old 05-17-2019, 05:37 AM
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Default Re: Idle Air Control Valve

The test is in the FSM. I think it goes like this: center pin to either outside pin should be on the order of 30 ohms. Open circuit is bad. So set the meter to the 200 ohms scale for this test. Then also test for continuity from any of the pins to ground. That should be open circuit.
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Old 05-17-2019, 05:44 AM
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Default Re: Idle Air Control Valve

Originally Posted by mk378 View Post
I think it goes like this: center pin to either outside pin should be on the order of 30 ohms.
The 4th gen 91 Civic FSM lists 8-15 Ohms. This specific test is not mentioned in 5th or 6th gen FSM, but I think they are similar.
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Old 05-17-2019, 06:31 AM
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Default Re: Idle Air Control Valve

Originally Posted by mk378 View Post
The test is in the FSM. I think it goes like this: center pin to either outside pin should be on the order of 30 ohms. Open circuit is bad. So set the meter to the 200 ohms scale for this test. Then also test for continuity from any of the pins to ground. That should be open circuit.
Originally Posted by muellersfan View Post
The 4th gen 91 Civic FSM lists 8-15 Ohms. This specific test is not mentioned in 5th or 6th gen FSM, but I think they are similar.
Thanks!

Please excuse my ignorance, but which test lead do I put where, in order to do these tests?
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Old 05-17-2019, 06:42 AM
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Default Re: Idle Air Control Valve

Set up the meter by plugging the black test lead into the COM socket and the red one into V/ohm/mA on the front. Turn the dial to 200 ohms. With the leads not connected to anything you should see a single 1 on the left side (open circuit). With the leads touched together the display should change to near zero.

Then put one lead on the center pin of the valve (it doesn't matter which) and the other one on an outside pin and take a reading. Do the same thing with the other outside pin. Then put one lead on any pin and one on the body of the valve and confirm it is open.
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Old 05-17-2019, 07:00 AM
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Default Re: Idle Air Control Valve

Originally Posted by mk378 View Post
Set up the meter by plugging the black test lead into the COM socket and the red one into V/ohm/mA on the front. Turn the dial to 200 ohms. With the leads not connected to anything you should see a single 1 on the left side (open circuit). With the leads touched together the display should change to near zero.

Then put one lead on the center pin of the valve (it doesn't matter which) and the other one on an outside pin and take a reading. Do the same thing with the other outside pin. Then put one lead on any pin and one on the body of the valve and confirm it is open.
Thanks, thatís very helpful!

Set the meter up as described and with the leads not connected to anything I see a single 1 on the left side, but with the leads touched together the display still shows a single 1.

I put one lead on the center pin of the valve and the other one on one outside pin and then the other outside pin...

On my original IACV I got readings of 22.1 & 9.2.
On salvaged IACV, I got readings of 22.8 & 22.6.

Then I put one lead on a pin and one on the body of the valve and display for both original & salvaged shows a single 1.

Looks like salvaged is better as both are closer to 30...

Thoughts?

Last edited by g4384063; 05-17-2019 at 08:33 AM.
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Old 05-18-2019, 07:59 AM
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Default Re: Idle Air Control Valve

Ok, well...I replaced the IACV and bled coolant system as follows:

Elevated the nose of the car with ramps.
Filled the coolant, squeezed the upper hose a few times to suck some more.
Started engine, with heat all the way hot but no fan, no lights, no radio, no electrical accessories on.
Let the engine run until the thermostat started fan twice, making sure to keep coolant as full as possible.
After the fan cycled twice I reved engine a few times to help push bubbles out.
Put rad cap on, and shut down the engine.

HOWEVER, A few minutes into bleed, the idle started bouncing between 1,000 & 2,000 and never stopped.

Afterwards, I took car for a drive and it seemed to be running much better than before I replaced IACV. It was idling a bit higher than usual, at about 1,300 but not bouncing like during bleed.

Unfortunately, when I got back home and put car in park, the idle started bouncing between 1,000 & 2,000 again.

Any ideas?
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Old 05-18-2019, 09:34 AM
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Default Re: Idle Air Control Valve

Originally Posted by g4384063 View Post
Ok, well...I replaced the IACV and bled coolant system as follows:

Elevated the nose of the car with ramps.
Filled the coolant, squeezed the upper hose a few times to suck some more.
Started engine, with heat all the way hot but no fan, no lights, no radio, no electrical accessories on.
Let the engine run until the thermostat started fan twice, making sure to keep coolant as full as possible.
After the fan cycled twice I reved engine a few times to help push bubbles out.
Put rad cap on, and shut down the engine.

HOWEVER, A few minutes into bleed, the idle started bouncing between 1,000 & 2,000 and never stopped.

Afterwards, I took car for a drive and it seemed to be running much better than before I replaced IACV. It was idling a bit higher than usual, at about 1,300 but not bouncing like during bleed.

Unfortunately, when I got back home and put car in park, the idle started bouncing between 1,000 & 2,000 again.

Any ideas?

More bleed please.

Code now gone?
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Old 05-18-2019, 11:16 AM
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Default Re: Idle Air Control Valve

Originally Posted by muellersfan View Post
More bleed please.

Code now gone?
Thanks!

Hmm? Finished off last of green coolant, only have new Honda blue, now. Perhaps itís time for a flush...?

Yes, code gone now.
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