Iacv issues

HASSAN SHUAIBU

MEMBER
1995 HONDA ACCORD
2.7L
V6
FWD
AUTOMATIC
166,000 MILES

I recently want to set my car idle speed. I was surprised after I remove the two pin plug from the IAC body, the engine rpm did not stall or act abnormal. It continues to idle normal as if IACV is still plugged in. But despite that, I do not really have any problem with the idling. Is the IACV still okay? Since the rpm is still normal after I remove the plug from the IAC. And how can I test the IACV with a multimeter tester?

1 Reply

CARADIODOC

MECHANIC
33,873 POSTS

You can only test between the wires for continuity, but no mechanic would waste his customer's time doing that. The Engine Computer will detect an electrical problem related to it and it will set a diagnostic fault code.

It sounds like you're expecting this assembly to work like they do on Ford products. In fact, on almost all other car brands, the "idle air control" valve, (aka "automatic idle speed motor"), is a "stepper" motor. What that means is the armature is pulsed with varying voltages and polarities that place it in a specific position. As that armature turns very slowly, it is attached to a threaded shaft that retracts or extends a pintle valve. As that valve retracts, it exposes more of an air passage around the throttle blade. At the same time, the computer varies the length of time the injectors are pulsed on. Together that is how idle speed is adjusted. If you unplug the AIS motor, it simply will no longer turn when an adjustment is needed in idle speed, such as when you shift into gear.

When you start the engine, idle speed should immediately shoot up to 1500 rpm, then drop down to normal a few seconds later. If that is occurring, the valve is working and the air passage is not plugged with carbon.