From all the reading i have done, it seems that in order to adjust the idle you need to turn the solenoid on top of the IAC and NOT the throttle stop screw on the throttle body. On my '91 EJ22 (installed in a VW camper) the IAC solenoid has only one possible position. In other words, there are no slots for the two screws (that hold the solenoid to the valve) to allow the repositioning of the solenoid on top of the IAC.

 

How do you adjust the idle with out these slots AND NOT TOUCH THE THROTTLE STOP SCREW?????

 

Many thanks for the help.

You are not meant to adjust it. The computer keeps it at the right revs if it can. If your's is idling at the wrong speed it is because there is something wrong... vacuum leaks, faulty compressions etc.

Actually I should have mentioned that I was originally trying to fix a cyclical idle problem by shooting carb cleaner in the intake of the IAC. I did remove the solenoid part of the IAC to actuate the shaft up and down while I blasted its innards. The cyclical idle is fixed, now it just idles high.

 

The engine is recently rebuilt and all vacuum hoses are brand new, so vacuum leaks/compression are most likely not the problem.

 

If the idle is indeed unadjustable and fully controlled by the ECU, will it learn to idle as I drive it more?

What is it idling at? You can adjust the screw to some degree. Although you might just need to setup your TPS sensor.

 

http://www.main.experiencetherave.com/subaru_manual_scans/FSM_Scans/

 

Go to TPS testing.

What is it idling at? You can adjust the screw to some degree. Although you might just need to setup your TPS sensor.

 

http://www.main.experiencetherave.com/subaru_manual_scans/FSM_Scans/

 

Go to TPS testing.

 

It idles some where between 1000-1100 rpm. The TPS's idle switch was correctly adjusted using a feeler gauge. So I am stumped.

there is two idle screws one on the top and bottom. I am not even sure why there are two.

there is two idle screws one on the top and bottom. I am not even sure why there are two.

 

From all the research I have done, this is a no no. Why this is, I don't know. They say to only adjust via the solenoid on top of the IAC valve. Since my IAC does not have this capability, the screws on the throttle body may be my only choice.

The ecu has a target idle speed which is fixed for life. Trying to alter the idle by moving the isc solenoid is taking the valve away from the middle of it's travel, which means it can't idle up if the air-con or lights are on, the motor is cold etc. Better to fix whatever is wrong.

Have you checked your neutral switch is operating correctly?

You've got a problem some where else you need to fix. Adjusting the IAC solenoid or set stop screws is trying to fix a symptom, rather than the problem.

 

I'd start with your basic tune up stuff and see if that helps.

i think even though the vacuum hoses are new, you probably forgot to hook one up somewhere....

Vacuum leak. Double check all of your hose connections.

Don't keep trying to adjust it - the computer will just keep re-adjusting it for you to compensate for the underlying problem. Check the PCV valve- have see a few cause high idles because of stick- specially after doing top end cleaning. Here's a trick to look for vacuum leaks- take throttle body cleaner and spray along vacuum lines- watch for change in idle- if it changes, that's where the leak is at. Don't forget to check the gasket at the throttle body itself . Another common cause of poor idle is the throttle body being dirty around where the plate seats in the body- take cleaner and a soft tooth brush to clean it. The deposits stop the plate from fully seating and let extra air past - computer adds fuel to compensate. This is very common on vehicles that are driven around town mostly (city vs. highway miles).

Plug the IAC lines entirely and see if the idle drops.

 

If it does, then you're IAC is stuck open.

 

The ONLY time you need to adjust the throttle stop screw is when you are using a new engine with you're original intake, or some other combo of engine intake that was not original.

 

The throttle stop is set to where it is to keep the throttle plate open VERY slightly, to allow idle air into engine, and to keep it from closing and wedging into the throttle bore. Each one is tuned to the particular engine it is on at the factory. When you put a throttle body on an other then original engine, you sometimes need to adjust this screw. BUT....that is only after all other conditions for idle have been met (CEL codes, no vac leaks, all sensors working...etc...)

Edited August 6, 200916 yr by Gloyale