My car started idling fast when hot and it turns out the thermowax plunger wasn't fully taking the throttle off the fast idle cam.

I tested the thermowax and it still contracts and expands as it should. I adjusted the screw so the cold alignment mark on the cam lines up with the roller. But the screw is turned almost all the way in.

So does the thermowax slowly deteriorate in a way that it's plunger moves lower into it's body? Why would this be so out of adjustment when supposedly nobody messed with it? Is it time to buy a new thermowax, before reinstalling the UI (again!)?

 

Not uncommon for any thermowax system to fail after a while.

 

I figured so. Now I don't know if it's to blame for a rough idle and stinky exhaust, where before it was smooth and clean.

 

No, if the throttle body thermowax fails it will keep the idle high. It won't effect the idle making it rough or stinky unless you have tried to compinsate for it instead of just fixing it.

 

What is the best way to make sure that the thermowax is working properly... is there a way to do it with the throttle body still on the car?

Cuz i tried letting it warm up and then looking back there and i could barely see anything... didnt have a mirror at the time... i will go back and try a mirror next time it stops raining...

what exactly should i be looking for also? (my idle stays at around 1200)

 

as the car warms the fast idle cam on the back of the throttle body will start retracting

 

if you have some help take off the hood.. gives you alot more space to work around