View Full Version : idle up solenoid?

09-07-2007, 08:26 AM
ok so i went to the toyota dealer to get a computer diagnostic. my car has a really bad idle and check engine light comes on after driving for a while. it idles at 600rpm and when i gas it, it kinda hesitates to get going. so they told me my "idle up solenoid" is broken, timing is out of adjustment, broken vaccum lines, and TPS is improperly adjusted. i changed the TPS because another shop told me that it was causing my bad idle. they were wrong and finally decided to go to toyota to avoid more incompetent mechanics. my question is what the heck is an idle up solenoid part #9091013004? what is its purpose? and also what does it look like? thanks in advance. any help is appreciated.

09-07-2007, 05:06 PM
You unfortunatly scored a less than brilliant mechanic at the dealer....
Go back and tell them your ECU reads air pressure, not airflow.

A vacuum leak in your engine will cause your idle to raise, not lower.
If it's bad enough it will surge.
Your broken vacuum lines are NOT causing a low idle.
They might even be helping your engine to run at this particular point in time.

Unfortunatly there are relatively few mechanics that know much about pre OBDII diagnostics and MAP based systems.

Start by fixing your timing. That WILL effect idle speed.
Also, if your TPS is out of adjustment it can also effect it.
Did they install a new one?
Is it adjusted correctly?

Your idle up solenoid [ISC or Idle Speed Control Valve] could also be causing problems.
It is on the bottom of your TB [Throttle Body]. It has 2 coolant lines and a vacuum line going to it.
It can be cleaned rather than replaced, however sometimes it's better to replace it, which is what the dealer usually will do to guarantee it's fixed. Cleaning doensn't always fix it, and if it doesn't work you will end up paying them again to replace it....

And while your vacuum lines are NOT causing the low idle, it is probably best if you replace them.