Adjusting idle speed

[Khanhfucious]

Anyone know how I can raise my idle a couple hundred RPM? Its idling around 500-600 right now and I want it a little higher.

[studum]

I thought it was done automatically by the ECM and not adjustable...

[shazapple]

yeah, it isnt adjustable. Why do you want to change it?

[Khanhfucious]

Damn. I have a humm from the motor that only happens when my car idles low. When I barely rest my foot ont he pedal and it raises the RPMs to around 750ish, the hum goes away.

[Huffer]

It is adjustable.
You have to have a dealership use the Subaru Select Monitor - they can set upper and lower idle limits.

I did this on my 99 Impreza once, it was idling at 600 so I had it raised to 700.

[scottzg]

you can also set the idle screw so the throttle is always a little [more] open. Subaru says not to do this, but i do it to crank the idle to teach ppl to drive stick. Just mark the factory position with a paint pen.

[shazapple]

I found this
http://www.northursalia.com/techdocs/pd ... rottle.pdf (http://www.northursalia.com/techdocs/pdf/engine/throttle.pdf)

so yeah, no touchy screwy

[Wiscon_Mark]

Damn. I have a humm from the motor that only happens when my car idles low. When I barely rest my foot ont he pedal and it raises the RPMs to around 750ish, the hum goes away.

You have any sort of intake mod?

[Khanhfucious]

I have the hum whether my intake is on or off

[jey]

you can also set the idle screw so the throttle is always a little [more] open. Subaru says not to do this, but i do it to crank the idle to teach ppl to drive stick. Just mark the factory position with a paint pen.

I use this screw too, no problems. If you change the idle by a lot, you can potentially skew the TPS's reading (it will think your throttle is like 0.5% open when the car is idling). To fix this you have to loosen your TPS and adjust that a little too.

Messing with the idle can be a real pain, though, because the ECU and the IAC does compensate for anything you do with that screw. So you can successfully raise the idle speed to 750, but then you shut the car off and the next time you start it up it will compensate and be back down to 600 again, I found, so you might be fighting a losing fight with the ECU with this whole process.

[SammyDaFish]

you can also set the idle screw so the throttle is always a little [more] open. Subaru says not to do this, but i do it to crank the idle to teach ppl to drive stick. Just mark the factory position with a paint pen.

I use this screw too, no problems. If you change the idle by a lot, you can potentially skew the TPS's reading (it will think your throttle is like 0.5% open when the car is idling). To fix this you have to loosen your TPS and adjust that a little too.

Messing with the idle can be a real pain, though, because the ECU and the IAC does compensate for anything you do with that screw. So you can successfully raise the idle speed to 750, but then you shut the car off and the next time you start it up it will compensate and be back down to 600 again, I found, so you might be fighting a losing fight with the ECU with this whole process.

that's exactly why the throttle plate stop is factory set and should not be changed. the ECU sets target idle and will try to compensate until it can achieve it.