1991 Subaru Justy Engine Idling

Tiny
OSCARK
  • MEMBER
  • 1991 SUBARU JUSTY
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 23,000 MILES
Wow, what a great site! I have a Subaru Justy 3cyl 1.2L fuel injected 2wd. I recently purchased it with only 23,000miles! The only problem that i'm experiencing with this car is that it starts right up and runs and idles well when it's cold. But after drving awhile, the engine idles roughly, the rpm shakes up and down, and a loud knocking noise comes from the engine. This only happens at a stop. Otherwise, the car runs very well and no problem. Can you suggest what it could be? There's no oil or any fluide leak and the engine is very clean. The only thing that i've done was change oil, replace thermostat (heater wasnt' working along with temp gauge). Thank you so much!
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Thursday, February 18th, 2010 AT 10:26 AM

3 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,815 POSTS
Hi OscarK,

Thank you for the donation.

The idling system is not functioning correctly and it could be due to :

1. Vacumn leakages.
2. Idle speed adjusted incorrectly.
3. Dirty throttle body and Idle Air Control (IAC) valve.
4. Clogged coolant hoses to the IAC.
5. Insufficient coolant in system. Was bleeding done after replacement of the thermostat?
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Thursday, February 18th, 2010 AT 12:11 PM
Tiny
OSCARK
  • MEMBER
  • 2 POSTS
Can you tell me where IAC valve is located?
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Friday, February 19th, 2010 AT 2:24 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,815 POSTS
Sorry for the delay in replying. Seems the notification system failed yet again.

Our database do not have any information on your vehicle so I am not able to get the location of the IAC for you.

For most vehicles, it is attached to the throttle body and has 2 coolant hoses attached to it with a 3 pin plug.
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Tuesday, February 23rd, 2010 AT 11:50 AM

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