Idle Air Control Valve finally failed maybe (?)

[newhampshiresouthpaw]

I've got a 99 Legacy L, 30 year edition, 2.2, manual that my son's been using since he got his license. Ran the car without a MAF sensor for at least 6 months (bad idle and all car wouldn't run at all with the bad MAF plugged in, but could keep it running with it unplugged) Finally replaced the MAF, and an O2 sensor...and so all codes gone except the car still idles poorly at start up then stalls after engine was warm...dirty Idle Control Valve per suggestion of my mechanic and he tapped on it slightly which must have freed it up a bit because there was instant noticeable recovery and the engine would no longer stall...So we've been running the car with this better bad idling for about a month. This morning, he starts it up...it idles poorly, yet stays running...and then it stalled. He took the Impreza to school, and I kept looking the car over...oil was VERY LOW, but not out~ I'm hoping that the reason the car will not run at all now is because that idle control valve finally failed altogether. A seized engine wouldn't crank at all right? It cranks as I'm trying to start it, and then gives a kapoof out the tailpipe which was the same symptom the car gave when the BAD MAF sensor was plugged in. I think it's worth a $40 junkyard part to try to fix it~ New part ranges from $177 - $423 between 3 auto parts stores.

[Fairtax4me]

Possible the IAC is just totally stuck. They're easy to clean, but that may not fix it. I'd suggest removing the IAC to see if the port in the throttle body is clogged.

 

There are several hoses that attach to the intake tube. Make sure they're all connected and both ends of the tube are properly clamped. Also check the resonator tubes, make sure they're not cracked.

[newhampshiresouthpaw]

ty~ Also, I should mention how my son took off the original filter housing/filter @ the throttle body, and the one on the side and replaced them with a circular performance filter in front of the now replaced MAF. The larger intake pipe clamped onto the throttle body may not be tight enough. My oldest son just informed me that those performance filters need to be on a cleaning schedule and oiled and not sure if his brother has...~ Also, his new performance intake it didn't come with the right coupling part, so the filter is just duct taped on...I'm hoping you're right that the IAC is just finally totally stuck and likely because his modifications aren't quite right  lol~ I was shocked to hear the price of that part, so thanks again. My parents are having a 50th anniversary in 2 weeks for which I'm planning a surprise party...I'm already not sleeping thinking about how I'm going to manage that and so just didn't need to be thinking about a car problem especially since this ended up being a repair year to get stickers on all 4 just this past March :/

[Fairtax4me]

Oh goody lots to go wrong there.

The aftermarket intake tube don't ever have the fittings for the breather and PCV hoses that are attached to the stock intake tube. These need to be attached to the tube because they pull air into the engine and that air is not being metered by the MAF sensor. The result is you get a lean fuel mixture, which causes rough lumpy idle.

 

The oiled air filters have a tendency to coat the MAF sensor element with oil. Then it doesn't respond properly and can cause problems.

 

Fix all the handyman intake stuff before chasing other problems.

[AdventureSubaru]

Absolutely go back to the original air box and be sure your vacuum hoses are where they belong, and are tight and uncracked. Vacuum leaks can cause bad idle, stalling etc.

 

Running that long without the MAF can cause other stuff to go goofy. A good seafoam cleaning never hurts. 1/3 of in in your gas, 1/3 of it in your oil, 1/3 slowly down the intake. Guys out here in California use larger amounts down the intake that almost stall the vehicle to saturate and clean the catalytic converters and pass smog.