Idle speed/stepper motor

[poorpeet]

Hi,
I'm wondering if anyone can help. when ever I start the car, hot or cold the idle speed goes straight to 1200+ rpm. It stay there for 1-2 secs then quickly drops back to 650 rpm & idles smoothly. It only happens on start up not during normal driving.
Is this due to the way the ecu is set up, ie normal, or something else?
I was wondering if it is to do with the stepper motor? Is it possible for the ignition off base setting for this to be wrong so that it has to adjust itself when the motor starts?
If so how do you correct it?
Cheers
Pete

[Ricardo Bertone]

On start up from cold it should initially sit higher. Your idle at 650rpm sounds low though - usually around 800-900rpm. Mind you the rev counter isn't deadly accurate.

Ricardo

[poorpeet]

No its not a rev counter problem, hot or cold it goes to 1200-1500 then drops back & idles properly.
As I don't have pas or aircon and if its the stepper motor thats causing this do I really need it?

[That Daddy]

Poorpete ,thats what your car should do,as long as it settles to a good idle shortly after, your idle should be about 800/900rpm,you will find when you slow down and come to a halt the revs stay up about 1200rpm,then drop to normal idle this is also correct.

[oggs]

Sounds fine to me... although 650 is low tho

[sam gamgee]

oggs said:

Sounds fine to me... although 650 is low tho

Agree...

Dave

[poorpeet]

Cheers all.
Pete

[BadRedWedge]

Have you set the base idle ?? The stepper motor has a limited range and can only control your idle speed within that range, if the base idle speed is out this can cause some problems. It sound like the stepper motor is doing its job it starts fully open, 1500 rpm, and then sorts its self out to drop the revs to a decent tickover, 650 is a bit low though.