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TECHPRO49, ASE Certified Technician
Category: Subaru
Satisfied Customers: 961
Experience:  Owner at Baltic investments
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Surging at idle when hot. Runs ok until warmed up. Has died

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Surging at idle when hot. Runs ok until warmed up. Has died several times if left in drive with brake on. If placed in neutral or park when it is surging, the idle goes to about 1200 rpm then slowly comes back to about 800rpm ( normal) , but it goes back to surging when placed back in reverse or drive.
JA: How many miles are on the car? What size is the engine?
Customer: 2010 tribeca
JA: Are you fixing your Tribeca yourself? What have you tried so far?
Customer: 80k, I-6
JA: Anything else you want the mechanic to know before I connect you?
Customer: Haven't tried anything yet. Researched forums, might clean MAF sensor and or idle air control valve, if it has one.

Hello my name is ***** ***** welcome to just answers! I will be assisting you with all of your vehicle questions today. Give me one moment while I review your question and come back with a answer. Please be aware I do not know your skill level or abilities so I will be asking a lot of questions and in a lot of cases we will respond to each other quite a lot before we find a solution. As far as phone calls are concerned that is the system prompting you, not me, and they do cost more money, I prefer text but in some cases a phone call is required. If I don’t answer right away or quickly in conversation I am helping another customer or have stepped out for a moment and will respond as soon as I can. Ok lets get started!

are you getting a check engine light or any other lights on in the dash?

Customer: replied 1 month ago.
I'm not an ASE mechanic but I have a bit of experience with vehicles. I have my own OBD code reader.
No DTC yet on the Tribeca.
Surging lessens a bit if I turn off the A/C, but it will still stall the engine on occasion.

So with no codes, I would start with the MAF and throttle body clean and idle relearn, there is special MAF spray you need to use on that, you can get it at any auto parts store, I also recommend for the throttle body clean a tooth brush and very aggressive carb cleaner and a towel to wipe out the excess there should be no carbon residue visible when done. After that, unhook battery neg first then pos, touch both terminals together and let sit for 30 mins, re apply pos then neg cables and perform relearn, 10 mins idle no accessories on, 10 mins accessories on and I mean everything in the car that can turn on , then 10 mins in drive with accessories on, turn off and restart and test drive

Customer: replied 1 month ago.
Ok. I have MAF cleaner. The procedure you described with the battery cables, etc... is for the idle relearn?

yeah thats a general idle relearn that you can use on just about any vehicle, that is assuming the maf clean and tb clean straightens out the idle issue

Customer: replied 1 month ago.
Ok thanks. If it works, I give you a great review.

sounds good, if it dosent we are just getting started and can try many many more things, this is just the first thing to do with that symptom

TECHPRO49 and 2 other Subaru Specialists are ready to help you

hows it coming?

Customer: replied 22 days ago.
The cleaning and idle relearn worked great until just the other day. My wife claims it did it again after a long drive with cruise control on. She drove home without cruise control and it didn't surge. Not sure if that is a related symptom or not. I have not been able to get it to surge again.
Any ideas?

it is very easy to get debris stuck in the MAF, I would pull that and check again and make sure your air filter is clean

Customer: replied 9 days ago.
It still surges when hot, and only when you come to a complete stop with it still in drive. I can keep it from dying by applying gas and brake together (power brake). Still no DTC showing up. Local Mechanic thinks it my be the torque converter or transmission. ATF level is a little over full when hot. Have not checked it cold yet.
Where should I go next?
Customer: replied 9 days ago.
MAF is clean. New air filter.