Idle Air Control Solenoid Problem
 

2 weeks ago I had this replaced as no 24 fault was showing and CEL light came on at times.
2 weeks later, after not coming on at all, it has come on again giving 24 as the fault again!
Any ideas please?
Subaru checked it originally and said it was the problem but I have replaced it with a used one.
Unlikely it has the same fault as the original.
Car runs fine, although idle revs do drop a bit when coming to a stop, but it has always done that.
The light tends to go out as I slow down for a junction.
The car is a MY99.
Thanks in advance.
Dave.

hi got the same prob on a my 97 replaced the Solenoid twice and replaced the engine to a sti v3 but code 24 comes back ...john

had the same problem wat the solution guys?

That's what I want to know!
Didn't come on at all today.

yeah i have the exact same problem on my 94 wrx. it's really annoying and when the check engine light is on i'v been told its retarding the timing on the ecu which is even more frustrating. i'll be keeping an eye on this thread fr solutions.

Hope some one can be of help...

Cheers..

There is a proven test to for this one, but it's not very easy to carry out. plus you need some not readily available test gear.
The easiest way i can think of to rule out what normally causes this, is to swop the ecu itself, if you can beg, steal or borrow a like for like ecu, it would be worth trying.

i have switch to a power fc but still idle drop. so i have try compensating it on the fc controller to reduce drop but it still annoying

ive swap it with 2 ecu still no joy dam that code 24 .......john:brickwall

sounds like a wiring problem then

ive checked the wiring but its all good but code 24 cums back:confused:

yeah its a mystery. i changed the solenoid and the actual valve and still same code ??

Maybe this could work.

I use an autronic Ecu and the Idle Valve controll on the MY99 is pretty difficult to get right. The problem is it uses and bipolair stepper for valve position. In mine opion there are two problems with this: it is just slow to react and it can loose steps easy when sticking to the end stops.

On the autronic site the only remedy is to adjust the throttle plate. This means when valve is completely closed engine still idles at a minimum of 800 rpms when hot.

So i would suggest to:
- unscrew the IAC valve
- pull the plunger out to its maximum deflection. (some force is needed.)
- reposition the IAC ( if done correct the plunger touches it end position before the valve is completely bolted on.
(valve is now closed)
- disconnect the connector to the valve.
- adjust the throttle plate screw out a little
- Start the engine
- when completely hot adjust throttle plate screw untill engine idles at 800 rpm.
-now reconnect connector.

This way the engine is not able to go below 800 rpm even when valve is closed.

Although I don't know for certain it will cure the fault code but the idle dropping would be cured.

This should work for MY99 and beyond the older cars have a different valve actuator probably solenoid.
But I guess adjusting the throttle plate should still work.

have brought mine to a subaru dealer for diagnostic testing and found no problem with the signal from the wiring harness the tester was plug in. Have ty to borrow a working 1 and replace it on mine and still no difference

As I can not see any difference in the car when the light is on I am going to ignore it!
If it didn't have a CEL I wouldn't know there may be a problem anyway.
I will take it back to Subaru only if the fault becomes noticeable.
Just changed my K&N filter to a Blitz one but I can't imagine that will change anything.

Dave have you tried an ECU reset?

Found this link on SIDC when doing a search for your problem:

Main Heading Goes Here

even our local subaru dealer is puzzle with this problem. They cant even solve this problem of mine also