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  #1  
Old 09-24-2003, 01:40 PM
Green1995SVX
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RX: Car won't idle when cold.

I put about 800 miles on my RX this weekend and all was well. That is until I tried to start the car on monday morning.

Here is what happens:

The car starts right up and revs up as normal. Then after about 5 seconds the rpm's drop quickly, and the car stalls. This can be avoided by pressing the gas pedal. Once the car warms up (must hold the gas pedal down to keep the revs up for about 5 mins, very annoying) the car will idle just fine when you take your foot off the gas. You can drive the car normally then and there are no problems. Once the car sits long enough for the engine to again cool off, the problem returns.

My original thought was that it could be the IAC. I removed the IAC valve and cleaned it out with carb cleaner per the advice of a tech at kerven. This had no effect on the problem.

I now have no idea what it could be. I really would love to get the car fixed as im driving my svx around now with an almost-dead transmission and two bad wheel bearings. Also, with how my driveway is, i have to keep the rx in the garage and leave the svx out until i get the rx fixed and running properly.

Can anyone serve up some advice for me?

Mike
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  #2  
Old 09-24-2003, 02:08 PM
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benebob benebob is offline
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Do you have an anti diesel valve? I'm guessing no b/c you have MPFI right plus it'll idle fine when it gets warmed up. Let me think on this one. You may get some quicker help over on the Ultimate Subaru Board.
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Old 09-24-2003, 03:03 PM
Green1995SVX
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thanks ben-

I posted on ultimatesubaru.net
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  #4  
Old 09-24-2003, 04:35 PM
oab_au oab_au is offline
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I don't know what a 1988 RX is,but it would have a cold start air valve. On the SVX its on the left side of the throttle body. Rotary disk valve that is electrically heated to allow a fast idle till the valve heats up to close.
It must be there somewhere It will have a couple of 1/2" hoses running from one side of the throttle plate to the other.

Harvey.
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  #5  
Old 09-24-2003, 06:20 PM
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Mike,

Harvey I think has hit the nail on the head.

If you find such an animal, pull off the hose which goes to the engine/manifold side of the throttle ( or both hoses if you like ) and if the result is continuous fast idle you have found your problem. You could even run the car like this temporarily if you are desperate.

Trevor. Only one good eye. *<)
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  #6  
Old 09-24-2003, 09:16 PM
Green1995SVX
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OK here are the results. I unplugged the coolant temp sensor, and the problem went away. I think I found my problem!!

Mike
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  #7  
Old 09-25-2003, 04:33 PM
oab_au oab_au is offline
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Quote:
Originally posted by Green1995SVX
OK here are the results. I unplugged the coolant temp sensor, and the problem went away. I think I found my problem!!

Mike
10 out of 10 for Mike.

Harvey.
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  #8  
Old 09-25-2003, 06:33 PM
Green1995SVX
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Well i replaced the temp sensor and now the car runs fine when cold but wont run at all when hot! AHHH The thing is up the street and im waiting for it to cool off so i can drive it home.

Mike
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  #9  
Old 09-25-2003, 08:09 PM
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Quote:
Originally posted by Green1995SVX
Well i replaced the temp sensor and now the car runs fine when cold but wont run at all when hot! AHHH The thing is up the street and im waiting for it to cool off so i can drive it home.

Mike
Stick with it Mike,

Provided the transducer is the usual type the resistance should reduce when the temperature rises i.e. from a high resistance when the engine is cold. (It will have a negative temperature coefficient.)

Are the connections and wiring OK allowing the reduced resistance to be registered ? Indications are that you could have a faulty connection or cable. There is usually two connections as the engine/chassis ground is not used so as to prevent earth loops.

As your previous fault was the reverse this could mean you previously had a short circuit but now have an open circuit. All this presumes the replacement sensor is the correct type and OK.

You could also try disconnecting the battery in case the ECU has got itself in a knot and requires resetting.

Regards, Trevor.
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  #10  
Old 09-25-2003, 08:30 PM
Green1995SVX
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There are two pins on the sensor. The plastic on the original connector was very brittle and it fell apart when i removed it from the sensor. Because of this, I had to guess as to which pin went to which wire. My guess is that I had the wrong wire on the wrong pin and i need to switch them. I disconnected the sensor totally hoping that i would be able to get the car home that way but it wont run with the engine hot disconnected. I'll try in the morning.

Mike
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  #11  
Old 09-25-2003, 09:45 PM
Green1995SVX
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fixed! Well it was my own stupidity that caused the last problem. I didnt tighten the clamp on one of the intake hoses on the engine side of the turbo so it pulled off a piece of aluminum ducting and was causing a HUGE air leak behind the MAF. Plugged everything back in and the car is better than new.

YAY

Mike
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  #12  
Old 09-26-2003, 05:46 AM
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huck369 huck369 is offline
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Mike,
Glad you got it fixed....those temp sensors cause a lot of problems on the XTs too


Oh yeah, another tip, clean the contact area of the conector wires, and put some di-electric grease on them to keep moisture out of the conection.....this will save you problems down the road.
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Last edited by huck369; 09-26-2003 at 05:49 AM.
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