Car stalls when stopping after ECU reset

[Casezilla]

When my ECU gets reset (e.g. due to battery being unplugged), the car stalls when slowing to a stop for a bit (probably takes ~10-20 miles of driving) until the ECU can properly adjust. Other than when coming to a stop, it starts and idles just fine (e.g. no stall on initial startups after the ECU is reset). No codes get thrown when this happens.

 

 

 

Is this potentially an indication of some sort of issue (AFR issue due to bad sensors or injectors?), or something that isn't too unusual for an older turbo Subaru (216k miles)?

[Abductee]

I would have issues with my idle for a little while after a reflash (reset ecu same thing). One thing that helped be fore the miles were driven to relearn the fuel trims was-

After reset I would place the key in the ignition in the on position without touching the gas pedal or starting the car. Do this for 30 seconds. Then start the car again without touching the throttle and let it idle for 2 minutes. Then drive normal. Do you have any idea what your fuel trims look like? You may have a vacuum leak somewhere

[chato]

it has to learn idle after a reset but I've never had stalling occur.

pulling a learning view or logging would give you an idea if the fuel trims are really far off which would be an indication that something's wrong.

lots of potential causes like, dirty MAF, a small vac leak etc that could cause the unlearned idle to be too low to keep the car running.

[Casezilla]

I'm not sure about the fuel trims, I don't have any logging equipment. The powertrain is stock (original turbo ), stock map (). Sounds like logging would be the next step, I might even be able to borrow some logging equipment, but it also couldn't hurt to clean the MAF and check for vacuum leaks.

[Holla]

This is normal. Even when I disconnect my battery, the car will die at idle for the first 20 miles or so.

[Max Capacity]

FWIW, I clean my MAF yearly if not twice a year.

 

I have not had this happen in the 16 years I've owned my wagon, or 9 years with the Spec. Both cars are on Cobb AP.

 

It is known to leave the key in the "On" position for 10 seconds after resetting the ECU. Then drive the car for a few miles as you would normally drive it.

[chato]

Probably worth grabbing a cheap vag-com cable that can pull learning view. Its been years since I looked at it but I seem to remember there's a specific chip code that works with the learning view software. Feel like this is a must-have for all turbo legacys if you don't have other logging capability.

[Abductee]

https://www.btssm.com/

You can dig up more info here

[Casezilla]

Thanks, I'll look into that

[KevinEdgar]

This is normal for what I'm used to, stalls a few times after ECU reset, then learns parameters and is good.

[5thGenCVT]

Yeah thats normal, it happens when you disconnect your battery the car basically has to relearn all the fuel trim and throttle mapping. It usually goes away after a few miles of driving when it relearns everything. There are some tricks to reset it after removing the battery though, look up Mr. Subaru on youtube he has some good videos explaining the process. I've tried it it works, hope that helps!