1990 Subaru Legacy IDLE

BJHANSON

MEMBER
1990 SUBARU LEGACY
4 CYL
AWD
AUTOMATIC
285,000 MILES

Car ran fine until last week. Now when it gets hot, the idel is so bad it won't hardly run and stalls even when driving low speed. No engine light. Worse than a simple vacuum leak. It has to be a part - but which one. If you tell me the part, please give instructions on how to install. I am pretty good backyard mechanic.

3 Replies

RASMATAZ

MECHANIC
75,992 POSTS

When was the last major tune-up? If done recently start by checking the fuel pressure if okay-test the idle air control valve /motor, throttle position sensor/EGR and PCV valve then report back for more assistance and thank you for the donation.

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Thursday, September 11th, 2008 AT 5:22 PM

BJHANSON

MEMBER
3 POSTS

OK -We replaced the spark plugs and wires. And we found and replaced the Air Idle Control Valve w/motor. No help. I adjusted the new AICV clockwise (which I think increases air flow) and the throttle body idle screw - it runs a little better. I do not think this is a vacuum problem per se - also checked all the hoses thoroughly. Engine runs fine as soon as it is out of the idle circuit - no missing, good ignition, starts immediatly. PCV seems fine. Disconnecting throttle sensor, AICV, and air intake elctronics have the expected effects - check engine light and engine dies. My son thinks it is one fuel injector, but. Runs fine above idel - is that possible?
Replace the EGR? Is that worht doing?

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Saturday, September 13th, 2008 AT 12:38 PM

RASMATAZ

MECHANIC
75,992 POSTS

Open up the EGR valve and look for carbon that maybe blocking the pintle from closing completely also check the fuel pressure.

Also attempt to pull the computer for code/s.

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Saturday, September 13th, 2008 AT 12:44 PM