Occasional Low Idle? - 2004 Outback 4 Cyl / Manual Trans

[cpyne]

Sometimes when I pull up to a light, my 2004 Outback will idle at a very low RPM and sound like it is about to stall out. I've never actually seen it stall, but my initial gut reation is to hit the gas to get the RPMs up. Most of the time it idles fine though. Any ideas what could cause this?

Thanks
Charlie

[cardoc]

Try cleaning the throttle body and the air control valve. The air control valve is mounted on the throttle body and held in place by 2 screws. It has an o-ring seal so don't lose it.

If that doesn't correct it, try spark plugs.

[highest_vision]

Something else to check out is the air assist injection solenoid/related bits. P0065 is the relavent code. Will rarely set a code, but can cause these symptoms nonetheless.

James

[coult45]

mine does this too, its a lot worse right after I reset the ECU/unplug the battery, and after a few days typically goes away and idle is better.

not sure what it is

[CSFiend]

Originally Posted by coult45

mine does this too, its a lot worse right after I reset the ECU/unplug the battery, and after a few days typically goes away and idle is better.

not sure what it is

In this case - because you've disconnected the battery - the ECU needs to relearn idle. On some of the automatics I've had, the proper method to relearn idle was to set the parking brake and leave the car idling in drive for five minutes.

With my 5 speed, after the engine swap the motor wouldn't hold an idle for almost a week of driving around. Not sure what the proper method to relearn idle on a manual trans is.

[cpyne]

Thanks Everyone. I was going to try CarDocs advice first on cleaning the throttle body and the air valve.

I can clearly see that air valve on other pics of 2004 engines, but mine is a bit different looking. This may be a dumb question, but does mine have an air valve? Here's what it looks like....

[cardoc]

Yours has an electronic throttle. No IACV. Just clean the throttle body. Carbon build up around the butterfly tends to throw off the measurement sent to the ECM. Also check the PCV valve.

[cpyne]

Thanks. Here's what I did....

1. Took off the throttle body and cleaned a ring of crud off the butterfly and throttle body. I didn't have a new gasket handy, so I reused the old one, but there were no obvious signs of damage.

2. Pulled out the PCV and blasted it out with carb cleaner. It seemed a bit oily, but not totally gummed up.

3. Changed the plugs. The right 2 were covered in oil. I'm guessing I have a bad valve cover gasket? I didn't change the wires. I believe they are original. The car has 115k miles on it. I was just outside looking at them in the pitch black, but didn't see any arcs. Think I should replace or keep going?

I started it up and so far so good. It doesn't have the low idle problem all the time, so I'll have to drive it around a bit before I know if the problem is gone.

Thanks again for the advice. If you've got any other pointers based on what I said above, please let me know. I'll reply in a few days to the thread and let everyone know if the problem clears up.

[radio head]

I had the same issue on my OBW (same drive-by-wire setup as well.) Cleaning the throttle body made a world of difference, including better drive-ability at low speeds (car was always very jumpy before cleaning the throttle body.)

[cpyne]

This seems to have fixed it. Thanks!