Right my idle was fluctuating between 800 -1050ish and occasionally throws on the check engine light code 24.now this isn't a constant problem it will sometimes sit at 800 perfectly for a long period of time,come to next set of lights and it will drop below 800 then straight back up and fluctuate 800-1050 ish quite gracefully then settle at 800 again.
I have taken icv off,cleaned inside checked to make sure everything moves freely and cleaned the diaphragm and just inside inlet and both surfaces for new gasket and re assemble.
Let the car idle up to temp and adjust idle to 800 once warm and then disconnect battery for 30min to a hour to Clear stored code
Start car and let it idle at 800 for a while then out for a drive and then same problem and eventually check engine light and code 24!
I have had throttle position sensor set correctly,no air leaks,maf seems ok and the car dies when unplugged
Tried a second hand icv and was promised it worked so I cleaned with new gasket and repeated same steps as above and still pretty much the exact same problem
It's not a majorly rough idle but annoying sitting at lights and junctions but is there anything else I could try as a new icv is quite pricey if it won't cure the problem
Any suggestions please and apologies for the essay

 

Did you clean the throttle body? And do an ecu reset after replacing the icv?
Worth a reset before you start looking at other parts.
Possibly a faulty coolant temp sensor?

 

Hi,yes I have reset the ecu and the check engine light comes back on after a period of driving, throttle body is fine and been told by a specialist to leave it alone
Would the temp sensor throw up code 24?
Also should of mentioned for the period the check engine light is on it will idle slightly rougher and settle down abit once light goes off
Thanks

 

Bad track/potentiometer in throttle switch.

 

If it's running a cone filter try putting the standard air box on with a upratedd panel filter .I've had 2 imprezas that spat their dummies at cone filters but ran fine on standard air box

 

It's all standard,no engine/performance mods at all other than exhaust system with a sports cat

 

This was adjusted a set correctly at zen,assuming you are talking about the tps,I don't have a multi meter to re check again

 

You have an intermittent fault and its throwing code 24 so unless its the wiring you have possibly a bad track on the pot in the tps. Setting the idle voltage is simple as you know so swap with a known good one.

 

Ok cheers mate ill have a look into that

 

I've had a similar problem. It's a bad grounding and/or knock sensor

 

I'll have a check over the grounds today I think
any signs of a bad knock sensor?

 

I'm not sure. Literally only know cos I took mine into scooby garage yesterday with pretty much the same problem. Idling at 4-800 rpm, then after 10 mins idling at a mates house engine light comes on but idling is now 500rpm no jumping.

Andy c said it was faulty knock sensor or bad grounding making the ecu go to safe mode, stopping any damage to the engine. Though since I had a new knock sensor just a few weeks ago, I've left it there while they look over the grounding.

Hope that helps

 

Yeah thanks mate,it gives me something else to think about