06 Outback low idle

[Pinotguy]

My 06 Outback sedan, auto, 75k miles runs great, but has a very low idle, about 500 rpm. Recently the engine stumbles when coming to a stop or when slowing to near stopped. No codes, or check engine light.
Any ideas?

[gbhrps]

I finally got fed up with my 07 OBW LTD doing the same thing last week and dived into the problem. Same issue as yours, low idle at stoplights, shaking and vibration, and no engine codes, 156 000 km or 97 000 miles.

I put a fuel injection cleaner in with a full tank of gas, and installed a new set of platinum spark plugs (Bosch single electrodes).

The change, in my case, was dramatic. That zippy car is back, and the low rpms and shakes are gone. Good Luck!

[plain OM]

gbhrps

That improvement is interesting. But it leaves me wondering -- was it the injector cleaner, or the plugs, that did it?

How long had the previous plugs been in use (kms) and what condition were they when removed?

p.s. which injector cleaner did you use?

[Pinotguy]

Only 1000 miles on new plugs. I'd like to try a cleaner, but which one?

[tdelker]

Stumbling was there before the plug change?

[gbhrps]

Gentlemen,

OK, some clarification. The stumble at idle, shaking, and hesitation on initial launch, was all present before the plug change and the fuel injector cleaner application.

The correction to all of the problems was almost immediate, and noticeable the next time I had the car out for a drive. Unfortunately, my wife had the first drive using the Subie, while I was relegated to the diesel dually, just because that's how vehicles were parked in the driveway, with her car barricaded in the garage.

I asked her how it ran after my fix, and she said that she hadn't really noticed. (Read ego deflated on my part, as well as some frustration.)

The very next day I got to the Subie first and it was very easy to see that the problem was fixed. I would have to say that the platinum plugs made the biggest difference, simply because there hadn't been enough miles put on the car for the injector cleaner to have done much in the way of cleaning.

As for which injector cleaner I used, it was whatever bottle I latched onto at the parts store, I don't recall. I'm sure that others on here can suggest their favourites, and maybe they're all the same. (I was really going to use SeaFoam, but the store I went to didn't sell it.)

I purchased the car new, and changed the original plugs out at 35 000 km by putting in Bosch Platinum's then. From anything I've seen over the years, platinum's are supposed to be good for 100 000 km, which would have been about the mileage that my last set had gone before the stumbling problem.

Hope this helps!

[plain OM]

From anything I've seen over the years, platinum's are supposed to be good for 100 000 km, which would have been about the mileage that my last set had gone before the stumbling problem.

Okay, so 100,000 km on the plugs that were replaced. Sounds reasonable that the plugs were the issue.

Thanks for the clarification.

[tdelker]

My question was to the OP: Was the stumble there before the plug change?

[cardoc]

Originally Posted by Pinotguy

Only 1000 miles on new plugs. I'd like to try a cleaner, but which one?

Use a 12 oz bottle of Sea Foam in the gas tank with a full tank. By the time you burn 1/2 the tank its cleaned out the system including the injectors and combustion chamber.

Low idle could be lack of fuel or air. When's the last time the fuel filter was replaced? Carbon build up on the throttle body or plate will throw off the TPS sensor feedback, which will also effect the position of the throttle for idle. The throttle body is electronic, so CDC throttle body cleaner and a soft bristle tooth brush is best to use. The engine will start hard the first time due to flooding the intake with the cleaner, but it will blow it out.

Try these first and see what happens.



.

[Saint J VT]

Ours was idling about 300 to 400 RPM's. Slow enough that the low-pitch rumble actually shook some of our old window panes when the car would be idling near the house in the driveway and in the garage.

The car started running terribly at nearly 100,000 miles (just shy of warranty ending), and my wife took it directly to a dealer about 50 miles from here.

Within several hours, they had new catalytic converter(s) on the car and the idle was up to about 600 from then on. The CCs were apparently clogged, which I attribute to the alcohol they water the gas down with.