Hey Everyone,

I have an MY00 WRX that I just keep having problems with. It's in great condition(Engine bay looks new).

Recently I had a surging/stuttering under boost issue which Subaru and all other sources put down to the AFM. I changed that and it was the same. So I changed the practically brand new BKR6ES-11 Plugs that came with the car for PFR6B and all was Great.

Then an intermittent problem appeared, Starting mainly when taking off from stand still or down changing for a corner. The car will jolt between gear changes and then go into "Undriveable Mode" This Mode could last for a few minutes or until I turned the car off and on again- then do it again within minutes/seconds or not at all . It was so intermittent and now its gotten worse -basically getting to be all the time no matter how careful I try to drive the car.

Main problem is I can't hold a constant coasting speed - it will either just slow down or speed up - jerking between the two. For example trying to do 60km/h it will just keep creeping up, so you lift the very little throttle you have applied, and it will slow down, so you gently push the throttle again to maintain speed and there is nothing in the pedal. You hold the same pedal position then BANG - the drivetrain gets a shock as power returns. My Gear changes are disgusting in the "undriveable mode" unless you ride the clutch at a higher RPM. It's like there is no fuel when I very gently push the throttle and then it all comes in a big jerk/bang - which leads me to speed up again and on my way for a ticket. It is also embarrasing because you are always going slow/fast/slow/fast through roadworks or 60-80 zones and the cars is visibly jumping/lurching forward. It is much better at 100-110kmh but is still there.

When I push my clutch in idle drops to the first couple of lines on the Tacho(5-600rpm I assume) and hunts a little bit. When not in this "mode" it idles about 8-900rpm.

THEN!! I noticed when in this "mode", stationary or rolling at speed, in neutral I cannot hold any rpm from about 1500-3000. I goes Up/Down/Up/Down for a bit Hunting majorly then it burbles and The CEL comes on. Then If i take my foot off the throttle it goes down to 500-600rpm and the CEL goes out and idle rises a bit.

The CEL code is 24 -Idle air control Solenoid. I pulled it out and its quite clean - a bit of carbon. I think I have a fair idea how it works, but have no workshop manual for this car. I wiped it a bit and someone said to grease (why) it but I didn't and put it back in. I noticed the solenoid didnt move much in or out(1/4mm) just rotates - I assume when voltage is applied it controls the solenoid which adjusts the valve on the end to allow for closed throttle at idle, turning on a/c etc.

Now the car has never stalled (although almost when I try to hold revs at 2000 in neutral when it hunts for a while then burbles and light comes on, sound like its runnning on 3 cylinders when it burbles)

It sometimes goes in and out of this mode 5 times in a mintue, or stays like it for 30 mins, or used to go a week without doing it at all - BUT ITS GETTING SO BAD NOW

It feels more like a throttle position sensor problem than the Idle control solenoid. But I don't know. Ive only had car for a couple of months and it's all pretty new to me. So far all I've done is change the Radiator, Plugs(What a mission) and AFM/FIlter. The car is stock except for a 3" Hitech Exhaust(Cat back I assume) I use BP Ultimate 98 only and I don't thrash it. I just wanted a zippy daily driver.

I will test the TPS soon with a multimeter soon just to rule that out. And If I rotate the Idle control solenoid while it's installed while the engine is running it seems to affect the idle.

Is it possible the Idle control solenoid is Stuck/Sticking? Is it supposed to move without voltage? Can I apple 12 Volts to any of the Pins while out of the throttle body to see if it works?

Please is there anyone out there with any ideas? Am I damaging it by continuing to drive when it does this(Apart from clunking/wrecking the gearbox/driveline and wrecking the clutch). I tried swapping the AFM again with another but its the same.

I have searched and searched the internet and various forums and cannot really find anything similar with this hunting at 1500-3000rpm. RPM barley hunts at idle in this "mode" if at all. RPM is just lower than when the WRX is performing as it should.

Sorry for the long Post. I hope someone reads it all and can lead me in the right direction. I don't want to go to Subaru and fork out a heap for such a trivial problem.

Thanks Heaps Perth WRX Crew