Need help please. 96 outback, 2.2L, MT. 56K miles. Idles fine when cold and slightly warm 600 rpm. But after driving 20 minutes or so if i stop and run into the store then the idle goes wild. It will jump up to 1200 to 1800 rpm. sometimes i can kick it down with the gas usually not. i just replaced the IAC valve with a brand new OEM replacement no change. Unhooked the battery for an hour no change. Vacuum is 21 inches off the intake manifold. I am not getting a CEL. What should i check next? i have read things about the alternator, this is an Indiana built car and A flash update from subaru. Has any one with a 96 2.2L had this problem and fixed it?

Larry

Muskegon Mi

I had this problem with a Jeep Cherokee and it was the Throttle Position Sensor. Check it with an old fashion ohm or volt meter with a needle. The needle should swing steadily with no jumps.

 

Never hurts to check all of your grounds either.

i agree tps may have a short or open when hot in it.

 

get one or three from a yard, as they are really pricey.

You can test it, but i think on the bench its going to test fine, as its a hot failure

 

nipper

The crazy thing is why does the idle go crazy after i shut the car down for a brief time period then drive it again warm? Is there something that is getting messed up while it sits hot? Can the throttle position sensor do this?. I will clean the neg battery teminal and engine ground connections.

larry

The TPS does look like it has been worked on. maybe it is the culprit.

larry

You might also spray the throttle body plate with a carb. cleaner it may be dirty and as it warms the expanision is causing it to stick.

The TPS does look like it has been worked on. maybe it is the culprit.

larry

Cleaned out the TB, it was pretty dirty. we'll see if it does the trick. It was a easy job. thanks for the advise. will post results in a day or two.\

larry