Idle issue

[Gaz mr-s]

My engine has recently gone back into the car. Primarily it was out because of a gearbox change.
Whilst out a bit of maintenance was done, water pump, thermostat, etc, & the IACV cleaned by the garage. The car did not have any idling issues before the job, - it worked as it should. It did have a fair bit of throttle cable play, which I adjusted when the engine went back in.

When it came to starting the car for the 1st time the idle was too high 2k-ish. So the throttle cable play was adjusted. It didn't make any difference. The car alarm was also playing up.
A day or two later when the engine was again started (battery remaining connected) the alarm had settled down, & the idle speed was about right for a cold engine.

The job is now finished & I drove the car home (only 1 mile)
2 issues so far...the idle is 1600rpm. And when I coasted with the clutch in before a slow turning I noticed the idle pulsing slowly up and down. I think it did it twice, then reverted to the 1600rpm.

The garage owner said for a 50k car (although 19 years old) the IACV was pretty dirty. He managed the job fine.

Any suggestions please?   

[Carolyn]

The idle air control valve is not correctly adjusted.

He may have 'done the job' on the valve, but it ain't right!

[Carolyn]

As per our exchange of messages, here are a couple of pics.

The valve can rotate around the two mounting screws on the end.  They are five point torx...

The default setting is bang in the middle of its rotational range.

If you can see shiny bits sticking out from behind the screws, it's not on that setting.

If you set to default, it should be close enough.

[Gaz mr-s]

So when the screws are tightened on re-fitting is there a tendency for the body to move about, so diligence is needed?

[Carolyn]

I suppose so.  I hold it in place, tighten the screws so it just binds but can move, double check, and tighten down.

When the valve body is opened up to be cleaned out, carefully remove the rubber gasket, if you can,  Don't get carb cleaner on it, it will swell up and go soggy!  Lubricate all the bits that rotate with light machine oil (3-in-1 or sewing machine oil are perfect).

If the gasket is damaged, you can find a replacement on the interent from a Subaru IAC, which is identical.

[Gaz mr-s]

Excellent, this should help others too.