Good Morning All - my 1999 Outback (2.5/automatic) has developed a stumble at idle I'm having trouble finding. With the engine warm, transmission in drive, foot on brake (car stopped), the engine will intermittently stumble for a second or two, then clear up and run fine. The check engine light is not illuminated. I can't make it happen, but it does occur often. Other than that, it has good power and runs great. Any suggestions on items to look at will be greatly appreciated.

How many miles?

 

 

IACV is probably dirty.

 

nipper

Thanks for the quick response, nipper. The car has 135,000 miles; 30,000 on a new longblock. Is the IACV servicable, or must it be replaced? If cleanable, is a spray choke/carb cleaner ok to use?

How many miles?

 

 

IACV is probably dirty.

 

nipper

Does it hesitate at all when you start off? Especially if you are easy on the gas? I've had that issue caused a couple of times by carbon build up in the engine. You usually need something industrial strength to clean things out of this is the case.

 

Commuter

Nope, with the exception of the intermittent stumble at idle, no hesitation or any other problems.

 

Does it hesitate at all when you start off? Especially if you are easy on the gas? I've had that issue caused a couple of times by carbon build up in the engine. You usually need something industrial strength to clean things out of this is the case.

 

Commuter

Is the IACV servicable, or must it be replaced? If cleanable, is a spray choke/carb cleaner ok to use?

 

Yes, it can be cleaned. On my '95 Legacy 2.2 I found it best to remove it from the engine for cleaning. Not too difficult a job.

 

Try a search for IACV--lots of info here about it.

 

Good luck.

Yes, it can be cleaned. On my '95 Legacy 2.2 I found it best to remove it from the engine for cleaning. Not too difficult a job.[...]

Having a new gasket on hand might be a good idea. Since the problem is intermittent, I'd suggest checking electrical connections as well.