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Guest Message by DevFuse
 

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IAC valve


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5 replies to this topic

#1 brodiemg

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Posted 09 December 2003 - 05:43 AM

would this be causing both fans coming on all the time and keeping my temp gauge at ice cold? my 93 legacy wagon is cutting out also, help please? this is such a rad board, newbee here!

#2 intrigueing

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Posted 09 December 2003 - 08:56 AM

I would guess coolant temp sensor. Check to see if the car has any stored codes. http://www.surrealmirage.com/subaru has instructions on how to do so. The fans coming on would not keep the actual engine temperature ice cold, I'd guess the sensor is wrong. Is the heat warm? If so maybe your thermostat is stuck open.

#3 brodiemg

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Posted 09 December 2003 - 10:07 PM

no the heat never really gets hot. and what about this iac thing should i mark it and take it out and clean it with brake cleaner fluid? i called to see how much a new one is and its not even in anyones system.

#4 brodiemg

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Posted 09 December 2003 - 10:13 PM

no the heat never really gets hot. and what about this iac thing should i mark it and take it out and clean it with brake cleaner fluid? i called to see how much a new one is and its not even in anyones system.

#5 alias20035

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Posted 09 December 2003 - 10:57 PM

Possible causes:

* thermostat stuck open <- engine will take forever to warm up, and on cold days it never will. With a normally hot engine, the air from the vents at low fan speed should be unbearably hot after 10-15 seconds or so with a hand placed directly against the vent.
* coolant temp sensor <- common problem
* stuck radiator fan temp switch/relay <- less common problem
* radiator pressure cap
* air in the cooling system <- If none of the above, I would drain the cooling system from the radiator drain (back lower left of rad, looks like a wing nut in most cases) into a clean container and pour it back into the radiator using a funnel with a coffee filter to prevent any solid particles from entering the system. On the 93 Legacy I would raise the front of the car slightly and open the radiator bleed valve (top left of rad opposite to pressure cap). Also pour the coolant in very slowly, I take 20 minutes or more to add the full 6 or so litres of coolant that the Legacy requires (use a small cup to pour).

IAC will cause cutting out, but not cold running, so fix the cold running first. Cold running will cause cutting out and misfires which will lead to very rough running! If your temp sensor is gone, the ECU may think the engine is hot (when it is not), and run a hot air/fuel mixture when a cold one is required.

The second fan should come on only when the A/C compressor is running (perhaps the ECU will trigger this fan too when the engine is really hot or with a bad temp sensor), does the second fan (right one when looking from front) run when your climate control in the "Vent" position?

With a low heat, fan constantly running, and rough running, you likely have a double failure of both the thermostat and the temperature sensor. With the engine off and cold, you can remove the radiator cap and start the engine, if coolant overflows the thermostat is stuck open. When the thermostat is open and the radiator cap is off, some of the coolant will take the path of least resistance and come out of the radiator fill. If the thermostat is closed, no coolant should overflow. Some cars will not overflow with an open thermostat, but Subaru's seem to do this, which is gives us an easy test for a stuck open thermostat. By overflow, I mean any amount small or large, if the thermostat is closed (thus working correctly) with the correct coolant level it will not overflow at all.

What do you mean by cutting out? Are your RPMS at idle erratic? Are the RPMS falling to 300 or so almost stalling and then jumping to 1500-2000 RPM? Does your cutting out problem go away if you open the throttle slighty? If all of the above are true, the IAC could be the cause, but fix the cold running first!

The IAC is a Subaru dealer only part (as far as I know). Try 1stsubaruparts.com, but again fix the cold running first!

#6 Legacy777

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Posted 10 December 2003 - 03:46 PM

As mentioned, check for codes and see if any are in there.

Alias gave some good feedback on possible causes.

Check the codes and let us know what you find out.




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