1999 Accord V6 Coupe. Started with a high idle, about 1000 RPM when in gear and 1200-1500 in Park or Neutral. Took the original Denso off and the little flap door was stuck open. Cleaned it real well and reinstalled and then the car was idle hunting and bouncing between 1000-1500 PRM in park, time for a new sensor. Picked up an "Intermotor" brand which is made by BWD, and basically looks like other "China" parts I have bought online. Installed it and the idle hunting went away, but high idle still remains. Took it back and exchanged for it for another one in a "CarQuest" box, same issue.(I think it is still a BWD part.)

Plug is getting power at pin #2 and there is continuity between it and #3 as the manual states to check. With the new valve installed if I put a piece of cardboard over the IAC inlet hole in the throttle body, idle drops back down to normal where it should be ~6-700 RPM so I know the sensor is the culprit and there are no other VAC leaks.

Anyone have experience with other brands? Is an OEM Denso the only way to go?(At $175 online!)

Not my throttle body, but for reference


Tried two of these valves, same issue as the one that is stock and stuck wide open.

 

The iacv is designed to idle high when on a cold start. As the engine warms up it will slowly lower the idle to 700 when the coolant is completely warmed up to 180-195. What you were seeing is normal.

 

Sorry it looks like I left out an important piece of info.......it does this when warm/at operating temps.

 

Then you have a vacuum leak somewhere. Did the iacv come with a new gasket ? If not, then you should pick up another gasket from Honda.

 

No vacuum leak. When I plug the IACV hole in the throttle body the idle returns to normal/where it should be. When I uncover the hole the RPMs go back up. It's definitely the IACV not closing as far as it should. My question is do other brands work better than BWD or is Honda/Denso the only way to go at +$160?

 

In a very rare circumstance maybe one but certainly not two.

 

try turning the ignition to on without starting the car and check for voltage at the iacv connector, should be none

 

Did you ever resolve your issue with the IAC? I have a 2003 Honda Crv and I think I am having the exact same issue. My car was revving low so cleaned IAC which worked for a week so I replaced my IAC twice, cleaned throttle body, cleaned connections, Code reads P0505 P1505. Still No luck. Since I switched out the first IAC it fluctuates from 1000-2000 in Park. Only thing I may have screwed up was performing the Idle reset procedure (revving to 3000 until fan comes on, let sit for 5 min) I did not realize I had forgotten to plug the TPS while I idid this. Ever since then it idles erratically.

 

Could this be as simple as low/no coolant flow through the IAC

 

Thanks for the quick reply. I was wondering about that myself. DO you think it would be an obstructed hose? How would the coolant be low or non existent in the IAC? I know how to turn a wrench but I am relatively ignorant when it comes to mechanics of cars.

 

You have an 03 CRV, which is a bit different than the OP's 99 V6 Accord....my post was more towards the OP.

I don't think I've ever had my head uner the hood of that gen CRV so I have to be honest and say any suggestions to you are based upon the "theory/history" of Honda engines, I don't even know the series of engines in the CRV's. On the Accord's some have found a blocked hose before but start simple and check the coolant level in the rad and the overflow. If low then top them off and see what you have....depending on how low you might want to follow the proper bleeding procedure for you car.

To check for a blocked hose, well either pull the thing and check....or (ONLY WHEN THE CAR IS COLD - HOT COOLANT IS A DANGER) pull the hose from the valve and crank it up....if you get a big mess of coolant, it is not blocked.and further testing is needed.