2001 gsr misfires in all 4 cylinders. Somone told me to start the engine and hold the accelerator steady at 3,000 rpm until the cooland fan comes on. Then disconnect the electrical connector to the IAC valve. The engine idle spped should drop or stall. So I did what they told me and there is no change of the engine idle speed. Does it prove that the IAC valve malfunction? Need some help. Thanks

 

there should be a change, usually it would go down to about 450rpm. got any cel codes?

 

No change in idel speed after unplug the electrical connector to the IAC valve. Idel speed stays at 900 rpm. It throws a code after unplug the connector. No code with connector intact and only got the 91, 93 misfiring code. So is it the IAC valve defected or should I replace the IAC valve? Thanks