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tamaz, Subaru master technician
Category: Subaru
Satisfied Customers: 1212
Experience:  Subaru certified,ASE Master technician,25 years experience
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Subaru Forester: 2010 Subaru Forster. last month or

Customer Question

2010 Subaru Forster. For the last month or so, the car has felt like it was going to stall out during idle. This seemed to only happen after driving it for a while.
2 weeks ago, after driving 20 minutes in the hot sun, I was idling the car in a parking lot and it stalled out. I turned the key and it took about 5 seconds for it to start.
At every stop light, the idle would slow and the car would shake like it was stalling so, I put the car in neutral at every light and revved just enough to keep it from stalling.
When I arrived home and came back out after 1 hour, the car started, but every time I would put my foot on the gas to pull out of the space, the running lights would dim, the car would shake a bit and 3 out of 4 times, the car stalled out.
Took it to dealer and they had it for 1 week. They were not able to replicate the problem after starting it 10 times every day. They said there may be a short somewhere in the car, but they cannot see anything because no warning lights have been signaled. They said it could also have to do with the hot weather and it wasn't that hot when they had it.
We have the car back and although it hasn't stalled, at stop lights, the car has a very low idle and when accelerating, it almost stalls out every time. I am unsure about what to do at this point. Thank you
Submitted: 1 year ago.
Category: Subaru
Expert:  Mike V. replied 1 year ago.
HI there,So when the issue is happening you get no check engine light coming on?Also, did you have any work done prior to this? Maybe a dead battery or something?
Customer: replied 1 year ago.
Hi Mike,
The only time the check engine light comes on is when the car slows idle and is about to stall, then all the instrument lights come on, like when you first start a car. If the car catches itself and doesn't stall, the lights go away.
We woke up to a dead battery about a week before it started stalling. We jumped it and it seemed fine, but stalling definitely didn't start until after battery. However, the idle problem has been happening for a while. Also, the dealer did a check on the battery and said everything ok...if that helps.
Expert:  Mike V. replied 1 year ago.
Ok, if its possible I would like to start with doing a relearn on the electronic throttle. Sometimes when the battery goes flat the computer will lose the parameters for the electronic throttle. This is a fairly simple procedure and will only require a 10mm wrench so you can disconnect the battery. I am sending the procedure and would like you to try it and see if it improves the situation for you and let me know.Subaru relearn:Turn on the car(key on engine off) make sure all the accessories are off. This includes A/C,fan,radio and rear defogger.Then turn the car off and disconnect the negative battery cable. Leave it disconencted for 15 minutes.Reconnect the cable and start the car. It may start and stall at first, this is normal. Restart it and let it run for 10 minutes,after it runs for ten minutes, turn the A/C on and let it idle for another 10 minutes. After that, turn the car off for 5 minutes. Turn the car back on and drive it, the idle should return to normal.
Customer: replied 1 year ago.
Hello. Thank you. I just finished the process. I started the car up and when I accelerated out of the parking space, the car almost stalled out. I reversed back into the space and the car almost stalled again
Expert:  Mike V. replied 1 year ago.
Sorry for the delay.The next thing I would like to have you try is to unplug the mass air flow sensor. This is the sensor on the air filter box lid. Unplug it and see if it will run better and let me know.Thanks
Customer: replied 1 year ago.
Hi Mike. I disonnected with no luck. It is doing the same thing. I reconnected and now is the check engine light is on, along with vehicle dynamics control warning light. Also, cruise light is flashing
Expert:  Mike V. replied 1 year ago.
Make sure your connected tightly. The lights should go out when you plug it back in.This one is a bit baffling. The only other time I have seen issues like this was a plugged up catalytic converter. It is possible, but sure seems unlikely on a 2010 in my opinion. I can open it up for the others if you would like. That's no problem at all.
Customer: replied 1 year ago.
If you wouldn't mind. I apologize, this perplexing and nobody can seem to find it
Expert:  Mike V. replied 1 year ago.
No problem at all, please don't reply back to me or it will lock it to me.
Expert:  tamaz replied 1 year ago.
Hi,let me see if I can help you,is the transmission a standard or automatic?Do you notice this problem when the electrical system is loaded up,a/c headlights radio etc.... you say the running lights dim so do you notice this problem occurring when its dark out side(I know it's sounds crazy but i have to ask).How many miles on the car?Has the easy things like spark plugs and air filter been checked?Does it matter how much fuel is in the tank?One more ...... what type of condition are the belts that drive the alternator in,thanks for your time