# Gremlins at long lights **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [September 24, 2012, 1:58am UTC](https://community.cartalk.com/t/gremlins-at-long-lights/74662 "2012-09-24T01:58:41Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![dawgMobile](https://avatars.discourse-cdn.com/v4/letter/d/ea666f/32.png) [@dawgMobile](https://community.cartalk.com/u/dawgMobile)\ **Post date:** [September 24, 2012, 1:58am UTC](https://community.cartalk.com/t/gremlins-at-long-lights/74662/1 "2012-09-24T01:58:41Z")
Dear cartalkville, Car: 2010 Forester Situation: Occasionally (3x a week or so) the car when recently started will, at a long light, start to stall and then catch itself. The last time rpms got so low the dashboard lights lit up for a fraction of a second before the engine caught itself and revved up to a normal 650-750 rpm. I have taken to the dealer 3 times; one time they kept it for 3 days, they can’t reproduce it. Took it home and the next day the gremlin was back. Ideas? Help? ---
**Author:** ![VDCdriver](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/vdcdriver/32/30_2.png) [@VDCdriver](https://community.cartalk.com/u/VDCdriver)\ **Post date:** [September 24, 2012, 2:01am UTC](https://community.cartalk.com/t/gremlins-at-long-lights/74662/2 "2012-09-24T02:01:19Z")
I would suggest that you focus on the Idle Air Control Valve (IAC) and/or a possible vacuum leak. Since the car is relatively new, I think that the chance of a disconnected vacuum hose is more likely than a gummed-up IAC. ---
**Author:** ![jtsanders](https://avatars.discourse-cdn.com/v4/letter/j/c2a13f/32.png) [@jtsanders](https://community.cartalk.com/u/jtsanders)\ **Post date:** [September 24, 2012, 2:19am UTC](https://community.cartalk.com/t/gremlins-at-long-lights/74662/3 "2012-09-24T02:19:29Z")
Is there more than one Subaru dealer near you? If it is something like a disconnected vacuum line, another dealer might find it. It seems to me that if the line was disconnected at the original dealer, they may overlook it several times. ---
**Author:** ![keith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/keith/32/5518_2.png) [@keith](https://community.cartalk.com/u/keith)\ **Post date:** [September 24, 2012, 4:51am UTC](https://community.cartalk.com/t/gremlins-at-long-lights/74662/4 "2012-09-24T04:51:26Z")
Automatic transmission? If so, I assume you leave it in gear and hold the car using the brakes. I also assume that the dealer just let it idle in neutral and that may be why they can’t duplicate the problem. I would start by listening for the sounds of a vacuum leak in the power brake booster. ---
**Author:** ![dawgMobile](https://avatars.discourse-cdn.com/v4/letter/d/ea666f/32.png) [@dawgMobile](https://community.cartalk.com/u/dawgMobile)\ **Post date:** [September 24, 2012, 5:52am UTC](https://community.cartalk.com/t/gremlins-at-long-lights/74662/5 "2012-09-24T05:52:03Z")
Thanks, everyone! Yes there is another dealer (though 1/2 hour away and no mass transit), but I think it’s time to go to them. Yes, it’s an auto, and yes this happens in gear with foot on brake, so, Keith, good idea. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [September 25, 2012, 3:44am UTC](https://community.cartalk.com/t/gremlins-at-long-lights/74662/6 "2012-09-25T03:44:01Z")
I concur w/@VDCdriver and all, this seems like an air leak somewhere. If unmetered air gets into the engine, it causes a lean mixture at idle. The effect of this lean mixture will be most noticeable when the car is stoped at a stoplight, the brakes applied, with the transmisison in gear. ---
**Author:** ![dawgMobile](https://avatars.discourse-cdn.com/v4/letter/d/ea666f/32.png) [@dawgMobile](https://community.cartalk.com/u/dawgMobile)\ **Post date:** [October 5, 2012, 10:09pm UTC](https://community.cartalk.com/t/gremlins-at-long-lights/74662/7 "2012-10-05T22:09:41Z")
PS. The coil went. They replaced it. But I swear the leak/problem is still there. Would these conditions be incidental. I can’t reproduce the idle-down/near stall systematically. ---
**Author:** ![oblivion](https://avatars.discourse-cdn.com/v4/letter/o/3ab097/32.png) [@oblivion](https://community.cartalk.com/u/oblivion)\ **Post date:** [October 6, 2012, 4:39pm UTC](https://community.cartalk.com/t/gremlins-at-long-lights/74662/8 "2012-10-06T16:39:17Z")
I can’t see how a failing ignition coil would cause the problem you’re having. If your car has coil-on-plug technology, the engine would miss and turn on the check engine light. Ditto if your car has a single coil or coil pack, except the engine would probably just stall with no warning and not just slow down. You might see if the dealer has a firmware update for your car’s PCM (computer)