Over the years on this site I have noticed more and more threads remain unanswered. Maybe we are getting less wiser on these 240's or maybe we are just getting lazy. So I will present a fairly simple question in hopes to get an answer. For the last few months my 240 has been idling very high. It has also caused the same injector to leak twice even after replacing the whole injector itself as well as the O ring. I got sick of driving it around with it running so poorly so I decided to look into a few things. I checked the spark plugs and they are fouled with fuel obviously. I see where fuel has been coming from injector number 2 or somewhere in the general area. Possibly the fuel rail nipple that is used to release air from the system. When I checked the IAC valve I clamped off the hose running from the IAC to the air intake duct. As I clamped the hose down the idle dropped dramatically. Now, here is my question. Since I noticed such a change in performance, is it possible that the IAC is stuck open and therefore that is what is causing my high idle? If so, I will obviously replace the IAC valve. Thanks.

 

I am also getting an ignition code 213 which has something to do with the throttle sensor. I read that this can also effect the IAC.

 

You can disconnect the IAC valve and inspect it. That will tell you if it's stuck. Removing the valve is simple - just be careful with hoses - those might have become brittle by now.

There's a flap in there that will move if you wave the valve around (sorry, couldn't think of a better way of putting it).

I would highly recommend that you take it out and give it a good cleaning. When I got my 240, I was having similar issues but not as bad as you are experiencing. The flap had carbon deposition all over and heating up it would cause the car to idle sometimes too high or sometimes too low.

Also, while you are there, I would suggest changing all the vacuum hoses (OE only, aftermarket is all Chinese junk. Plus the OE ones for our cars are affordable).

+1 on questions not getting answered here. All hail Pierce for helping everyone out always over the years

 

I removed, cleaned, and inspected the IAC about a year ago. So I feel at this point it might just be worth replacing. The problem has slowly progressed so I assume the IAC has slowly gone bad. Unless there is another issue that is causing the IAC to stay open. Throttle body, EGR, Flame Trap, etc cleaned and/or replaced as well about a year ago. Replacing the vacuum hoses is a good idea and something I plan to do soon but I have inspected them and I have seen nothing so serious to replace immediately although I do understand these hoses can have small cracks unseen to the human eye. I do feel that by clamping the hose down on the IAC which caused the idle to slowly correct itself it could either be the IAC or possibly another issue somewhere.