[quietride]

As reported by others, my new 2017 2.5i has been slightly erratic at low speeds. Noticed the TSB that recently came out for this indicates resetting the ECU 'normally' so thought I'd give it a try to see if it made any difference. Have had to use the idle re-learn with my 2008 Forester after disconnecting the battery (idle way too low without it) so figured, why not?

What did and didn't need resetting was odd. The date/clock, auto front window up/down function, and gauge check (set to off) needed resetting, but that was it. The seat belt chime remains off after the initial sequence, the lock/unlock beep stayed off, and the radio stations weren't lost. Weird.

Thought maybe the ECU didn't reset either but the idle was initially a bit lower, plus it ran differently for the first few miles. Still notice a slight erratic behavior at low speeds but it seemed to be diminishing over time beforehand so will just keep an eye on it for now. If needed I'll let the dealer do the TSB reset with the first oil change in a few months.

 

[forester6291]

after a battery change, I had the same problem, almost a stall at lights and stop signs, sometimes full stop. performed idle learn and instant fix,staying that way.

 

[evolver79]

This thread sounded a little hokie at first, but I tried it anyway. I just finished the STI TMIC install on my 04 FXT which required me to remove the throttle body and had a hanging RPM issue when coasting in gear. After I performed this procedure, it runs and idles perfectly! Thank you.

 

[strngr]

I've been having sporadic revving and rough idles. Then I tried this method and it fixed everything! Thanks for sharing!

 

[Rustydawg]

So, since I'm competely new to all of this, I have a programmed stage 3 pro tune and an AP. my question is, if i do this process to relearn the idle, would I lose the current tune, or could I keep the tune on the AP, or would the ECU not lose the tune and just learn the idle?.

 

[2.5x_sleeper]

So, since I'm competely new to all of this, I have a programmed stage 3 pro tune and an AP. my question is, if i do this process to relearn the idle, would I lose the current tune, or could I keep the tune on the AP, or would the ECU not lose the tune and just learn the idle?.

@Rustydawg that complicates things!

The poor idle could be caused by the tune? The stage 3 tune is a pretty aggressive tune, so you might want to contact the person that tuned your Forester to see what they advise.

You really don't want to disconnect the battery, until you know how your tuner installed the tune maps! This is how my COBB tuner does his programing, so yours may be different!

Whatever is put onto the ECU as the "Reflash" will stay regardless of a battery disconnect or ECU reset. We usually use the economy mapping for as the reflash. This is beneficial because it will be the map that the car defaults to in case of any abnormalities (dead battery, vehicle maintenance at other shops, etc.).

Whatever is put onto the ECU as the "Realtime" map WILL be lost during a battery disconnect or ECU reset. After a battery disconnect or reset, the current realtime map will default to the base reflash map is until you change it.

We usually use the additional boost maps as realtime. Realtime mapping is a great feature because they can be switched virtually instantly and without losing any of the learned parameters the ECU has stored over time.

Bobby...

['07 FSXT Member Journal] ['03 X Member Journal]

 

[Rustydawg]

Well, I guess before I go any further I should be certain its an idle issue, and not just the fan kicking on. Its really only happening at lights and in park. It feels like it drops low and also goes high, both by about +/-100 rpms with it settling at about 450 to 500 rpms. It seems like it gets kinda low and almost stalling out but comes back up. How do I be sure its not just a normal thing.

 

[2.5x_sleeper]

Start with the easy stuff, like cleaning the MAF sensor.

Bobby...

['07 FSXT Member Journal] ['03 X Member Journal]

 

[hydn79]

Whew. JDM 2006 Forester ej205 here. Dude!!!! So I added MBC about a week about. Noticable power improvement running 16psi (td04 turbo).

My left side HID stopped working. I swapped bulbs from left to right and saw that it's probably the ballast. But to do so in had to remove the battery. Then came out tonight and while parking the SF stalled a few times. Idle is way off, it's trying to idle too low.

BUT DUDE!!! I Read the forums and now I'm getting much better pulls from turbo and less backfires. So tomorrow I'm gonna buy MAF cleaner, disconnect again, follow similar steps and let the ECU tune itself again.

Thanks for this post. Definitely had zero stalls until battery pull.

 

[jeff122]

there is something in this

Hi . I have got a 2006 MY Impreza wagon EJ20, non turbo. I had the battery out overnight last night, and when I put it back in and started the car it ran like an old b*st*rd. it would not idle and I kept having to start it. I had to make a journey of about 10 miles and once it was rolling it seemed to improve.
Finally it was idling ok, and oddly, seems to have lost a hesitation it had at around 2500 rpm. Next time I disconnect the battery I will definitely try the 'idle learn' procedure :smile2:

 

[acmarinucci]

not BS, After you reconnect the battery, the car will continue to stall until its retrained. I tried to compress this proceedure and it cost me over $400 in towing, theft by the towing company etc.

 

[pebkac000]

A recent battery change resulted in the rev-hang issue returning for our 2009 model.
I have performed the reset procedure twice before using the instructions in the original post.
Today I did this,
Disconnect the battery for 10 minutes.
Reconnected the battery.
Turn the ignition to 'on' and wait for 20 seconds.
Start the engine and let it idle for 10 minutes.
Stop the engine for a few minutes.
Restart the engine and test drive with a successful result.

The disconnection time for the battery may be able to be much less but I have not tested a shorter time than 10 minutes.

It is most definitely a thing that happens and this procedure definitely works.

 

[Kevin]

^ yes indeed, tried and true! ;-)

 

[lgmayka]

The other day, the Subaru dealer replaced my battery (after 5-1/2 years and 95,000 miles). I am told that my car is ready to go; but when I try, it conks out repeatedly. An employee comes over and says that 3 out of 10 times, the car has to "re-learn the idle." He advises me to hold down the gas pedal while starting and idling the car. I am thereby able to get the car going. I ask him whether I will continue to have this problem after leaving the dealership. No, definitely not, he assures me.

My car conked out at the first stop light--with a large honking truck right behind me. The car conked out several more times in my garage, then again later in the day in a parking lot.

By the next day, the car appeared to be behaving normally.

 

[Ricofromchico1]

Thank you for the technical data...

I had followed a former thread about the speedo sensor and followed the insgtgructions to find out the cause. Perfect instructitons, they worked so I will try this method today, Gracias

 

[Barry James]

Hi all, i just came across this as I changed a dead battery in my 2012 today, but immediately recognized slight differences, being slower to start, low idling and lack of power off the line plus auto drivers window won’t work. Thought it was in my head, but visited Auto Electrician opposite Daughters school and he said the battery needed to be replaced professionally due to this and that, I replied, you joking? So Monday morning I’m revisiting him to see if he can fix it, what can i say? Unbelievable! Give me tye old cars any day!

 

[panixgr]

why not just unplug the ECM fuse? it is under the dashboard, driver side.

 

[JoseK]

Unnecessarily looooooooooooooooooooooooong procedure

After disconnecting the battery, the idle will be rough.

Simply find a place to park, switch off, turn key to on, let the gauges go all the way and back (I think its a self check or smth), start and off you go.
Works all the time on my 2.0 Spec.B GT legacy

 

[DockingPilot]

What a load of B.S. Internet mythology. I mean I'm glad it worked for you, but my battery has been disconnected dozens of times with no special "training" afterwards. I have a hard time believing any competently designed car would require a spurious mystic undocumented ritual to reset it after a battery disconnection!

-- Steve

Agreed. Ad I should know, I just replaced my battery this weekend. [emoji1787]


Sent from my iPhone using Tapatalk

 

[2.5x_sleeper]

I have recommended this procedure to forum members for years & it has worked for many of them. It only costs a bit of your time. If it doesn't work, you can move on to other troubleshooting.

It's true the ECM will eventually, relearn on its own, but it can take awhile. To some members, it's too long to wait & this procedure just speeds up the process.

We haven't needed to use the idle relearn procedure on either of our Foresters, but that seems to be the trend... some need this procedure & some don't...

Bobby...

['07 FSXT Member Journal] ['03 X Member Journal]