Low rough idle

[CoupedUpSubie]

Started to get a really rough idle on my drive back to school. I'm guessing it would idle around 400-500 and shake the whole car. Bring it off idle just a tad and it went smooth. I'm at 167300 miles now. Ideas and what to do to rule thing out?

 

[Legwagon]

PCV or IAC???

 

[CoupedUpSubie]

Very good possibility as I am sure they are original. PCV valve is cheap but an IAC valve $371. If that's gone it will be a JY part... just need the wierd 1.8 version

Would a dirty IAC also cause occasional idling at 1300-1500? I've been living with that problem also.

 

[Legwagon]

^that I'm not sure of ... someone else is gonna have to chime in.

 

[CoupedUpSubie]

Well I've done a bunch of searching and I will be cleaning the IACV as I think mine is sticking on occasion but working most of the time. Found that the ej18's built before the second half of 94 might have a similar IACV to the ea81/ea82. They said to pour some seafoam down the hose connecting the IACV to the intake and turn the car over pulling it through. Worth a shot or big DON'T DO IT?

 

[CoupedUpSubie]

Here is a picture to show you the IACV the 1.8 has. It's on the passenger side, one hose from the intake and another going to the top of the throttle body. I believe this is the IACV.

 

[jaKe]

try cleaning them

 

[CoupedUpSubie]

try cleaning them

I haven't dealt with these two particular items as of yet. The PCV is no big deal, $5-10 at napa. The IACV I am more concerned about where everything I find is for ea series engines or the newer style IAC that is mounted on the throttle body. Mine is on the manifold. I would rather not screw it up so I am looking for the proper procedure to clean it.

 

[Chris]

That vac solenoid on the manifold looks like it's for the evap canister, or the fuel tank pressure crap.

Follow the hose, I bet it either goes to the charcoal canister, or to the bottom hose under the two fuel hoses on the driver's side.

Only if it goes right to the intake is it iacv.

The ea82 one is actually mounted on the intake manifold. It's a cylinder bolted to a square block that's bolted to the intake manifold.

If it's the same, it's held on with four screws, take it off and clean it out, there isn't much in there. High idle could be caused by a dirty IACV, it did on mine, it was clogged up and couldn't close all the way.

Doubt PCV could cause a high idle, but maybe. It's not a bad idea to replace it anyway, seeing as it's so cheap and easy. Check for vac leaks. Old vacuum hoses are brittal and tend to crack when you start moving them around/exploring.

Also clean your MAF. Use only MAF cleaner, other stuff will ruin it. They can get dirty or even start going bad without throwing a code, but cause idle and run issues.

 

[CoupedUpSubie]

The solenoid does go to the intake just after the MAF. What should I clean it with? Electrical parts cleaner?

MAF was clean a bit ago along with the throttle body, and I used the correct cleaners.

 

[Chris]

The solenoid does go to the intake just after the MAF. What should I clean it with? Electrical parts cleaner?

MAF was clean a bit ago along with the throttle body, and I used the correct cleaners.

Now that you say it has a hose from the intake boot, to the solenoid, to the intake mani, I remember at some point telling you that's probably the IACV, or at least has something to do with the idle system.

Since I have the stuff sitting around, I usually use seafoam, Just pull it off, tip it so the nipples are straight up and fill it up with the stuff. Let it sit, shake it, dump it out. Hopefully that cleans it. The ea82 ones and later EJ ones you can see the moving bits in there and clean them better, maybe yours comes apart.

You'll probably also want to replace the vacuum lines after you take them off. They're probably hard and dry rotted and won't seal again when you put them back on.

 

[CoupedUpSubie]

Looks like a trip into Bucksport this week. I'm going to try putting a small amount at a time through the hose and running the car to pull it through. I'm not pulling it off while in castine.

 

[Chris]

It'll only go through if the valve is open. Your best bet is cold start at high idle. Take the hose off the intake and just stick it in the bottle.

Vacuum will suck the stuff in.

 

[Flipswitch]

The symptoms sound familiar & it was caused by a misfire for me.

http://www.mainelysubarus.com/forums/topic/12497-p0304-cynlinder-4-misfire/

Has the CEL come on or any codes from the OBD2?

When was the last time the plugs or wires were changed (worked for me but possibly due to voodoo)

 

[CoupedUpSubie]

The symptoms sound familiar & it was caused by a misfire for me.

http://www.mainelysu...nder-4-misfire/

Has the CEL come on or any codes from the OBD2?

When was the last time the plugs or wires were changed (worked for me but possibly due to voodoo)

Plugs and wires were done 2 years ago. Highly doubt that's the problem. It's OBD1 and no CEL, if it was misfiring I am sure it would throw a code. Also engine sounds to be firing on all cylinders with no power drop, its a 1.8 so a down cylinder would be very noticeable.

 

[Flipswitch]

ooh true

 

[Chris]

Depends what the plugs were changed with. If they're the cheap NGK ones, you're probably fine. I put bosch plats in my car, they melted in two weeks.

What about plug wires? They should be oem or NGK, otherwise they'll have issues. Subarus are picky about ignition components.

I doubt that's your problem though. If it was ignition related you'd be complaining about running rough trying to accelerate.

 

[CoupedUpSubie]

Cheap NGKs went in, did run bosch's "best" plug for a bit. Napa wires.

Car is idling was idling fine again. Still going to clean the IAC at some point.

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