2008 Outback does not idle right

[RyanL]

Hello, I have a 2008 Subaru Outback.  I bought it about a year ago.  Recently it started idling too slow, and even quit on me a few times.  Started right up again, but whenever I come to a stop, it gets very slow, low RPMs.  500 RPM or lower.  The engine light does not come on, there are no codes, except one time it did have a code: P0172 "System Too Rich Bank 1"  I cleared the code (months ago) and it has not returned.  Still, the idle problem persists.  Is there any idle adjustment?  What could be the cause of this?  Thanks for your help.

[brus brother]

It may be something as simple as tune-up but if that has been addressed, then consider the following.

Have you recently disconnected the battery or "cleared" any codes?

In doing so, the car's ecu then needs to relearn the car.

Start the car by just turning the key and let it idle without touching the gas for about 10 minutes. That first turn of the key may take a few revolutions until it starts but DO NOT step on the gas 

If I don't follow this step, I end up with a car that tends to stall out, even after many miles of driving.

[gbhrps]

Ryan L,

Always give the mileage of your car as that lets us zero in on issues that will show up  with higher mileages.

When was the last time that you 1. had the throttle body cleaned? 2. the Air Flow Meter cleaned? 3. done an Idle Relearn Initiation? 4.cleaned the Idle Air Control Valve?

All of these are easy to do for a DIYer and can all be accomplished in less than two hours in your drive way.

Go to YouTube and check out videos for each procedure under "subaru throttle body cleaning", "subaru idle relearn" etc.

[brus brother]

Subaru Idle Relearn Procedure:

1) Turn off the lights, aircon, stereo or any system in the car that draws extra current on top of the engine.

2) Disconnect the battery for 30 mins.

3) Reconnect the battery.

4) Before you start the car for the first time, turn the key to the ON position but do NOT turn the engine over. Wait 10-15 seconds so the electronic throttle body or IACV has time to go to the factory programmed home position.

5) After waiting, start the car and let it idle without any load, lights, A/C etc.

6) Every 20 seconds or so the idle will be adjusted up and down as the ECU tries to adjust it towards a stoichiometric fuel / air mix.

7) Leave the engine running for a full 10 mins but DO NOT TOUCH THE ACCELERATOR during this time or turn on anything that will cause extra electrical current draw.

8) Turn off the engine, and leave the key in the OFF position for at least 20 sec.

9) As per step (4) turn the key back to the ON position for 10-15 sec without actually starting the engine.

10) Start the engine and leave to idle for a further 5 minutes without touching the accelerator and without turning on other systems in the car.

11) Turn off the engine again and wait at least 20 sec before restarting.

12) Take the car for a test drive as the ECU should now be fully retrained.

 

 

[Rooster2]

My 08 Outback developed idle and drive ability problems. Turned out the EGR valve was bad. Dealer said this is a typical problem on the 08 model.

[LKalenda]

Hello,   2008 OBL 137K

I recently installed LED low beam lights.  It immediately started having idle problems.  I will follow the  Subaru Idle Relearn Procedure: from brus brother and see if that fixes it.  If not, I will look at the EGR valve.

[LKalenda]

The procedure worked.  Idle is good again.  Thanks

[brus brother]

7 hours ago, LKalenda said:

Hello,   2008 OBL 137K

I recently installed LED low beam lights.  It immediately started having idle problems.  I will follow the  Subaru Idle Relearn Procedure: from brus brother and see if that fixes it.  If not, I will look at the EGR valve.

makes sense. you did disconnect the battery to install the lights? that would require the ecu to relearn.

[jtl]

On 7/28/2019 at 12:39 AM, brus brother said:

Subaru Idle Relearn Procedure:

1) Turn off the lights, aircon, stereo or any system in the car that draws extra current on top of the engine.

2) Disconnect the battery for 30 mins.

3) Reconnect the battery.

4) Before you start the car for the first time, turn the key to the ON position but do NOT turn the engine over. Wait 10-15 seconds so the electronic throttle body or IACV has time to go to the factory programmed home position.

5) After waiting, start the car and let it idle without any load, lights, A/C etc.

6) Every 20 seconds or so the idle will be adjusted up and down as the ECU tries to adjust it towards a stoichiometric fuel / air mix.

7) Leave the engine running for a full 10 mins but DO NOT TOUCH THE ACCELERATOR during this time or turn on anything that will cause extra electrical current draw.

😎 Turn off the engine, and leave the key in the OFF position for at least 20 sec.

9) As per step (4) turn the key back to the ON position for 10-15 sec without actually starting the engine.

10) Start the engine and leave to idle for a further 5 minutes without touching the accelerator and without turning on other systems in the car.

11) Turn off the engine again and wait at least 20 sec before restarting.

12) Take the car for a test drive as the ECU should now be fully retrained.

 

 

Hello - Before doing the above, should I clean the throttle body first?

[brus brother]

My post is 4 years old.

Not sure what your issues are.

If you suspect maintenance is required, do that first.

I got that ECU relearn procedure from a Google search.