Trying to determine cause of low idle/stalling when damp

This is going to sound bizarre, but for about the past 4 months or so, when I first start my car in the morning and drive a few blocks and stop (say at a stop light) at idles REALLY low (around 200RPM). If I keep my foot lightly on the gas, it's fine. However, the other day, I didn't and it stalled. Starts right back up with no problems and initial start is fine.

The ONLY thing I can think of is that it happens when it sits outside. It's a 99 SUS Ltd. Sat outside until May of last year when I moved to a house with a garage. Bizarre as this is, at first I thought it was the air in Hershey PA. I travel there for work and when I come out of the hotel (generally once/week), I have this problem while driving the few blocks to the office. Come out at lunch, it starts right up. I know, does this sound REALLY strange?? Thought it was only when it rained, but last few weeks, no rain, just overnite moisture I guess, and it had these symptoms.

Yet this morning, my car sat outside all weekend in the snow and it started up and held just fine... so maybe that blows my dampness theory.

Anyway - I'm going to the dealer for an inspection and oil change Friday and they're going to look in to this but thought I'd try to solicit some input from here first.

Thanks!

Reply to
ismlv
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Could be IAC (idle air control valve), when the throttle is closed it bypasses to allow some air into the intake. It is an expensive part IIRC but also reponds to cleaning sometimes. Another issue with some newer cars occurs if the driver is in the habit of slightly depressing the accelerator pedal when starting. It seems the computer immediately records the pedal position as 'closed throttle' assuming it is not depressed, later when the pedal has no pressure on it the idle can be too low. Try clearing the ECU (disconnect negative battery terminal and depress brake pedal - wait 15-30 minutes or more, reconnect and start car (do not depress gas pedal) and drive normally. If you still have the problem it could be the IAC. Of course there could be fouled plugs, carbon build-up, other problems. Do a search on IAC over at the forums on

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see if your symptoms match.

Carl

1 Lucky Texan

ismlv wrote:

Reply to
Carl 1 Lucky Texan

Sounds just like my kids troubles with her Dodge. It never does it to me, and think she has a habit of foot on the gas when she starts.

The above is pasted to her windshield this morning. :)

Thanks Carl!!

Reply to
pheasant

I was surprised to see your message. I have a 1998 Outback Ltd with

40k on it. During the past two months it has started doing exactly what you describe. Initially it was when it was cold; however, now I can get it to do it almost anytime. If I brake hard at a light and come to a complete stop it will idle slowly, judder and often cut out. The dealer (and they are excellent from all my previous experiences with them) is baffled....they have worked on it for two weeks and contacted Subaru, still no luck. Nothing shows up on their diagnostic computers when it happens. So far we have tried replacing oxygen sensors and speed controllers - still no luck. I wondering if the problem stems from something that happened this summer. I was at a light with my foot on the brake when I was rear ended at about 2-3 miles an hour - this stalled the car out. Have you found out any more? Roy
Reply to
Roy Williams

Reply to
ismlv

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