Poor idle

[jewbaru]

Alright. So probably a lot of you guys kno that I've had a few issues these las couple months with cylinder 4. But I just got my motor back yesterday and installed. Wet the whole day with no issues. No more noise nothing. This morning I start my car. Everything was fine. Got down the highway to work and o the stop sign (now at operating temperature) and she almost stalls (it's an automatic). Get right on the gas and she seems a bit sluggish. Pull into work and park. My idle goes dOwn to like 250-300. And basically shuts off after 5 seconds..

Any idea why I'd have poor idle at operating temperature?

[geckoboy86]

After my experience with my old Civic, which was an auto and also did that kind of idling... I blame most of my idle issues on the Idle Air Control Valve (IACV for short)

[jewbaru]

I just put stage one cams in. They were good for about 2000 miles and I blew another piston. (apparently a vacuum leak?). But the knock from that has now gone away. And my oil filter was saturated with oil. I don't have a check engine light either. How can I diagnos iacv?

[jewbaru]

well, i took the car out on my lunch break and it started to stall again at idle as it was warming up enless i kept my foot down a little on the gas, grabbed lunch and almost didnt make it out of the parking lot on my way back to work. left the tranny in 3 or 2 on the ride back to keep the rpms up a bit. pulled into work and parked in my spot, and now.. its not stalling anymore and the idle is back to where it should be.. :-/

it still has a rough idle, but its just running a little rough which could b me interpreting the effects of the cams as a problem at idle, but i only have stage one cams, and a lightweight crank pully

when accelerating its real sluggish, and there seems to be a slight hesitation.. but nothing that effects normal driving situations

replaceing the IACV would cost me close to 4 bills.. so im not really looking to replace that if i dont have to

would a vacuum leak cause all of these problems?

the man who rebuilt my engine told me to inspect the vacuum line from the intake manifold (above cylinder 4) to the master brake cylinder, upon inspection the line seems alright, but has a hard buldge in it about 4 inches from the booster.. ill have a picture of that tomorrow

any ideas?? or tests you recommend i try?

[geckoboy86]

I'm trying to remember how I tested it (I'm glad to be rid of that POS)

I used forums and process of elimination. Plus my idle adjust screw didnt help any idling issues.
Subarus are new to me and so is the H4 engines.

[httrdd]

Vac leak would definately lead to rough idle. I have one now on my H6 and the car idles rough at times. Also had a vac leak on my f150 and the truck would try and stall.

[jewbaru]

how can i find the leak without access to a smoker or by using propane?

[httrdd]

Visually check all of the hoses.

[green97gt]

could also grab a can of brake cleaner, or carb cleaner, etc..something cheap...and spray it methodically around your engine bay, following the vacuum lines with it, etc.. the engine will stutter when a vacuum leak sucks up the cleaner.

iv found this very useful for diagnosing bad intake/tb gaskets