I just spent some quiet time with my throttle body freshly removed from my engine. I say quiet time because I was listening to the switch click as I manipulated the throttle cable linkage paying attention to where the plate was on both 'sides' of the click.
The Idle Switch is recently installed and new by the way and if you have ever installed one you know it has a range of orientation that it can be installed relative to the throttle body.
The conventional wisdom is it must be rocked all the way forward in order to function correctly. "Foward" as in the top of the switch when it is in the installed position will be rocked toward the firewall and the bottom of the switch rocked toward the front of the car then tighten the two mounting screws tightly so it doesn't loose it's position.

Well, I installed it that way last two times I was in there and only now do I discover that rocked all the way then tightened actually has the switch holding the shaft open ever so slightly! So slightly that I couldn't see it just by peering down into the mouth of the throttle body while it is installed in the engine...I know because over the last year or so I've checked that plate to see if it was held open by anything like a too tight cable or something and never really saw it.

If you attach the Throttle Switch to the plates shaft but leave it's mounting screws loose and make sure the plate is closed all the way you can then rock the switch slowly until you hear it click....that is where you want to lock it down....or...you can continue to rock it that direction after you hear the click until you feel the end of the switches range of rotation and lock it down.....basically rocked all the way. However, if you do that, the switch will be holding against the spring pressure of the throttle plate shaft linkage not just the plate at rest, and the plate at that point is just ever so slightly open!

I'll never know for sure if this was my high idle problem because I'm replacing the throttle plate shaft, and the flappy shaft, bearings at the same time I corrected this situation but it doesn't hurt to pass this info on since so many of us, for so many different reasons, are searching for the root of a high idle from time to time.

So rock that Throttle Position Switch forward but only until it clicks and lock it down tight, then check it a bunch of times before you reinstall everything.

 

Very good advice.

 

Glad you caught it. It is tricky to get it right. I make sure the throttle closes all the way against the stop and the switch trips a couple of degrees off the stop - as little as possible while still having a reliable on-off click.

 

Good advice

Thanks for the post.

 

Hmmmm.

I had the throttle plate out when I did the top end refresh. I wonder if it's not closing all the way.

Thanks, I need to check this.