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Old 10-22-2007, 02:36 PM   #1
bry593
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Member#: 161594
Join Date: Oct 2007
Location: Broken Arrow, Oklahoma
Vehicle:
1972 Datsun 240Z V8
Can-am White

Question 1990 to 1994 legacy idle air control cleaning

car has a strange idle.... cold start = 2000 rpms for a minute, then 500 rpms, then back to 2000, then back to 500.... eventually, it just idles rough and surges a little while driving...

sorta seems like no vaccuum leak, vac leak, no leak, vac leak....

pulled the codes, got a 24 = idle air control solenoid...

on this 2.2 legacy, it appears to be the mounted on the passenger side just behind the intake manifold. is this the valve? or is it located on the throttle body like a late imprezza? can i clean it with q-tips and carb cleaner and fix the problem?

anyone else experience this problem?
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Last edited by bry593; 10-23-2007 at 01:59 PM.
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Old 10-23-2007, 12:59 AM   #2
bry593
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nevermind, i got it.... these subarus are too flippin easy!!!!

the IAC IS that valve looking thing attached to the back of the passenger side intake, with all the hoses coming off of it... ....

here's how to fix the idle problem.... go to autozone and buy some sea-foam ($7.00).... warm the car up, jam a flat-blade screwdriver between the throttle cam and the stop to raise the idle to about 1500 rpm. next, pull the brake booster hose from the booster. next, put the lip of the can up to the hose. the vaccuum will suck it right out (AS A MIST, DON'T DUMP the can in or you could hydrolock and bust a piston/bend a rod!!!!).... anywho, the idle will come up to about 2000 rpm until the plugs start to foul and then it will drop. at this point, turn the engine off and let the seafoam soak into the carbon/varnish in the top-end. meanwhile, pull that big hose off the IAC.... well not off the valve itself, but the other end that is attached to bottom of the intake ductwork on the passenger side... it's about an 1-1/8" outer diameter and doesn't even have a clamp on this end, so it's really easy... dump a couple TABLESPOONS in the hose, reattach it, and let everything soak for 5 minutes or so.... start the car (you may have to press the accelerator pedal to give it enough air to ignite the seafoam).... rap it up to 2000/2500 rpm until it quits smoking....

next, repeat the process until 2/3 of the can are gone.... pour the remaining 1/3 of can into the engine oil and drive it like that for 200 miles or so. this will clean the varnish out of your engine and prolly free up any sticky HLA's (hydraulic lash adjuster, AKA lifters) you might have.... during this time, i wouldn't advise you to hotrod as the seafoam will thin out your oil. for the same reason, change your oil after a few hundred miles so you don't cause any undue wear. keep in mind, this legacy has 273k miles so it was pretty gummed up but now it purrs like a kitten...

that's it.... however, this is just a temporary fix until the IAC gasket comes in, at which time, i will remove the valve and give it a good scrubbing with q-tips and carb-cleaner (not soak the valve in carb-cleaner which will certainly screw up any rubber components)....

hope this diagnosis/instruction/advice will help someone else....

UPDATE ON SEAFOAM PER SEAFOAM TECH BULLETIN:

Sea Foam Motor Treatment used in Crankcase oil
All Gasoline and Diesel, Rotary style engines

Sea Foam Motor Treatment may be used in an oil crankcase 2 separate ways, depending on your needs and expectations.

Sea Foam Motor Treatment is most commonly used as a pre service old oil residue cleaner and moisture drier, and is also used as an after service additive.

1. As a pre service cleaner for old oil residue, sticky rings or valve train noise,
pour 1 ounces of Sea Foam Motor Treatment into the engine oil crankcase for EACH quart of oil capacity including filter. (Diesels use 1 pint to 4 gallons of oil, please) Drive a MINIMUM of 30 minutes/miles, MAXIMUM 100 miles, then do your oil change service (LOF). This begins the process of safely/slowly re liquefying the old oil residue so contaminants may flow and be filtered. This also makes your old oil dirtier, quickly, so a LOF service is necessary when the oil gets dirty. (LOF = Lube oil & Filter service).

2. As an after service additive into fresh oil, nearly fresh oil, or oil (used condition) that is NOT ready to be changed (by mileage), put the same amount of Sea Foam Motor Treatment into the crankcase as described above, then SELF SET a program to MONITOR your oil for color and clarity on a mileage, timed, or event basis (like every time you add fuel, etc.) to determine when an oil service is necessary. (LOF)

Sea Foam Motor Treatment will safely and slowly re liquefy old oil residue, This will make your oil need changing BEFORE your normal scheduled LOF service. Only your monitoring of the oil for color and clarity can tell when it is time to do LOF - oil change service, or 3,000 miles, whichever comes first.

Check your oil and monitor its color & clarity to determine need for LOF service!

Change your oil when it gets dirty!

Technical Services Department
Sea Foam Sales Company
Minneapolis, Minnesota
952-938-4811

September 2007


-bry

Last edited by bry593; 10-25-2007 at 08:09 PM.
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Old 10-25-2007, 03:31 PM   #3
IllNastyImpreza
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can you snap a pic of the IAC ??? I can't seem to figure out which one it is...

(this is on a 98 but I assume it looks relativly the same)
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Old 10-25-2007, 05:20 PM   #4
bry593
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1972 Datsun 240Z V8
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i'm working on an old 2.2 legacy. you have a newer 2.5 imprezza. your IAC is not the same, nor in the same location as mine. yours (i believe) is located on the throttle body (the thing your throttle cable goes to) and on the bottom side?
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Old 10-25-2007, 05:53 PM   #5
IllNastyImpreza
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i think I found it... not sure though.

its ont he pass side attached to the TB.... it has a rather large hose attached to it...

I'll see if I can snap some pics ...
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Old 10-25-2007, 07:37 PM   #6
bry593
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1972 Datsun 240Z V8
Can-am White

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take that big hose lose and follow my instructions from above. amazingly, it will fix the idle problem. my friend's legacy purrs like a new one... un-flippin-believable!!!!
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Old 10-25-2007, 10:36 PM   #7
IllNastyImpreza
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Join Date: May 2003
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Location: East Kingston NH
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DIY project: life
I need more TIME!

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it sucks cuz its a brand new engine...everything is polished clean inside and out... and the freakin IAC is the only thing clogged
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