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Hey guys,

My car developped a weird idle pattern during the past few weeks.

When i start it cold it'll idle high then idle really low even stalling the engine. It goes up and down during a few minutes before stabilizing.

when i drive at around 2500 RPM the car seems to hesitate but if i give a little gas it'll pop back into place.

When i'm at idle i usually get - 19 mmHg pressure but since this started i get 13-14 but if i rev the engine a little it'll go back down to 19.

any ideas what the problem could be?

Possibly a vacuem leak? But then again, I wouldn't really know, hell I can't even spell vacuem!
Micum

Search for IAC , specifically cleaning.

I suspect the IAC but is there a way to clean it without taking everything around it apart to gain access?

viewtopic.php?t=194&start=0

Look at my first post.

Ive done this three times (I own 4 subaru) and everytime it has fixed the problem you describe.

On va l'avoir not' permis de biére!

Something about not being permetted to have beer on the plane?

non je pense que ça veut dire qu'il va avoir l'age légale de boire
... je pense


thought I could confuse you a bit more

it's a famous line from a Québecois film "Elvis Gratton"

Should i use brake cleaner instead of carb cleaner?

Why would you do that? Brake cleaner is designed to be external to the engine, carb cleaner is made just for spraying into the intake. Id worry that brake cleaner would be too strong and might leave residue.

Funny thing is that if you look at the ingredients, the two are almost the same.

brake cleaner will not leave any residue.

After cleaning the IAC Solenoid, the problem was still present.

I unplugged the O2 sensor and now it idles just fine. when plugged it'll idle funny.

My new question is: Is a faulty O2 sensor automatically to blame? or can it be the MAF or something else? basically unplugging the O2 sensor just puts me in open loop. i don't want to replace parts just for the fun of it wich is why i ask.

thanks,

If unplugging the oxygen sensor made the problems go away, I'd say there's at least a 90% chance that the oxygen sensor is bad.

The only way, as far as I can see, for a non-oxygen-sensor-related problem to go away when you unplug the sensor is if it's related to timing. Without the oxygen sensor's feedback, the ECU is more conservative with ignition timing. Your problems don't sound related though.

Replacing the oxygen sensor is pretty easy and cheap. The sensor's right on the downpipe, easily accessed from above without any lifting or disassembly. You should be able to use any old sensor; you don't have to use the expensive Subaru one. You can even use a non-heated sensor, just tying away the heater leads. Morgie has done this.

Hey Guys,

I finally changed the O2 sensor and problem solved.