high idle when hot

[Kainnen]

I have a 91 N/T laser that starts up fine, idles great around 700-800 after it warms up for a few minutes but then after that it starts to go downhill. Once the car has been driven for 15 minutes or so and reaches operating temperature the idle starts to increase. It doesn't surge but it just climbs with each stop. Eventually it will be idling around 2000rpm and usually stays like that till the car is turned off and cooled down. I have had this problem since i got the car a year ago but it actually stopped doing it in the winter, now that the hot weather is back so is the high idle. Ive had the coolant flushed and the stock guage only shows the engine temp around halfway or less. Anyone have experiences like this with there cars?

 

[TwoLiterLaser]

Look at the easy stuff first, like idle screw, throttle cable, and clean the throttle body. Get back to us.

 

[ilikespeeding]

I have, but not in a DSM. I waited about 30 seconds then the idle went down. Do you have an aftermarket intake?

 

[Kainnen]

TB was cleaned, stock intake still on. BISS was adjusted and it idles perfect after a few minutes of warming up but then 20+min into driving it starts to climb. Could a throttle cable being bit tight really cause it to climb from 800 to 2100rpm idle, and it seems odd that it only happends when its hot out.

 

[TwoLiterLaser]

You never know...... Lossen that throttle cable and see what happens.

 

[Vert]

i've got the same problem with my 95gsx. The hotter it get, the higher the idle climbs. I've found that if I spray the TB with water, the idle will come back down. I don't know what's wrong either.
I'm open to suggestions too.

 

[propeine]

Hey I used to have this problem. My idle switch was bad so my ISC didn't know what to do about things. If I adjusted the BISS when the motor was hot it would barely idle when cold. If i set it to 800 cold, when it was hot it would idle at 1200.

 

[diatenshi]

I have the Exact same issue. Keep this thread updated.