Honda/Acura Idle Air Control Valve (IACV) Removal and Cleaning (EG/EK Civic, DC2 Integra)
- Hot coolant can scald; do this only on a cold engine.
- Brake and carb cleaner are flammable; keep them away from sparks and let the valve dry fully before reinstalling.
- Coolant is toxic to animals; clean up spills.
Introduction
On B- and D-series Civics and Integras, a hunting, surging or stalling idle is often caused by a dirty idle air control valve (IACV). The valve sits behind the intake manifold near the throttle body, is held on by two 12mm bolts, has an electrical connector, and has two coolant hoses running through it, so expect a small coolant spill when you remove it. Cleaning means flushing cleaner through its passages until it runs clean, letting it dry, and reinstalling it on its gasket. The Honda-Tech writeup notes it applies to all Integras except the Type R, and the HondaCivicForum.com writeup (https://www.hondacivicforum.com/forum/routine-maintenance-diys-73/iacv-cleaning-62836/) describes the same valve on D- and B-series Civics. Adapted from a community writeup by wildoutwhitegsr on Honda-Tech (https://honda-tech.com/forums/acura-integra-6/***how-clean***-your-iacv-k-idle-air-control-valve-1575913/).
Procedure
12 steps-
Step 1: Let the engine cool
Work on a cold engine; the IACV has coolant running through it and hot coolant can scald.
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Step 2: Make room
Remove the intake tube at the throttle body and, if fitted, the front strut tower bar, so you can reach the back of the intake manifold.
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Step 3: Locate the IACV
The valve is on the back of the intake manifold, near the throttle body, toward the firewall.
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Step 4: Catch the coolant
Pack a few rags under the valve to catch the coolant that will spill from the hoses.
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Step 5: Disconnect the coolant hoses
Squeeze the two spring clamps with pliers and slide them back along the hoses, then work the hoses off. Leave the hoses uncut; they are made to a set length and you would need new ones. A little penetrating spray helps if they are stuck. Plug the hose ends to limit coolant loss.
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Step 6: Unplug the connector
Disconnect the electrical connector on the driver side of the valve.
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Step 7: Remove the valve
Remove the two 12mm bolts holding the IACV to the manifold and lift it away. Keep the rubber gasket; without it the valve will leak air after reinstallation.
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Step 8: Flush the passages
Spray brake cleaner, carb cleaner or Simple Green into the valve's two openings and over the screen, and let it drain. Keep going until the cleaner comes out clean, which the writeup says can take anywhere from 5 to 15 minutes on a dirty valve. Do not use anything abrasive inside the valve.
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Step 9: Inspect the internal gasket (optional)
If you suspect an air leak, remove the screws on the valve body to check the internal gasket, then reassemble.
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Step 10: Let it dry
Let the valve air-dry for about 20 minutes so no cleaner is drawn into the engine.
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Step 11: Reinstall
Refit the valve with its rubber gasket, tighten the two 12mm bolts evenly, reconnect the electrical connector and push both coolant hoses fully on, sliding the clamps back over the hose ends.
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Step 12: Top up coolant and test
Refit the intake tube and strut bar. Top up the coolant and bleed any air as for a normal coolant service, then start the engine. Check for coolant leaks at the hoses and watch the idle as the engine warms up.
- Replace tired spring clamps while the hoses are off.
- If the idle is still poor after cleaning, check for vacuum leaks and a dirty throttle body before buying a new IACV.
- The location described here suits most B- and D-series engines, but one HondaCivicForum member could not find the IACV behind the intake manifold on a D15B2. Confirm the location for your engine before you start.
Related procedures
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