1.7 Throttle body/idle problems

[RichMason]

I have a 73 1.7 with an idle problem. Once the car is warmed up it idles high, between 1500 and 2000. If you let it sit, it will eventually settle down to a normal idle but the time required for this varies. I have adjusted the TPS to no avail but I noticed that the butterfly in the throttlebody sticks open sometimes and there is a slight ridge that has formed where the butterfly contacts with the inside of the throttle body. If I push the throttle closed manually, it idles normally so I am sure that this is my problem. So how do I fix it? A stronger spring does not seem to be the solution as the one I have currently is pretty stiff. Is there a bushing that needs to be replaced? I lubed the butterfly pivots/shaft but it didn't help. How about grinding/polishing the ridge where the butterfly seems to hanging up? Finally, should I just buy a good used one from someone on the board?

[norustscott]

Rebush the throttle body...any carb rebuilder can do it. $$$
trim the butterfly plate (zero $)
open up the tB throat is also a possiblity (zero $)

swap out for a another TB...lots of them around say guys?$

[Dave at Pelican Parts]

If the idle drops to normal when you push the throttle valve closed, then it is the problem. You can file or polish the ridge down, re-bush the shaft, and make sure the throttle plate fits well. Or you can get another throttle body.

Similar symptoms can be caused by an Auxiliary Air Regulator that does not have power hooked up to it or whose heating element is broken. Check for +12V on the wire that plugs into the AAR when the engine is running. (More properly, when the fuel pump is running.) And check the resistance from the plug on the AAR to its case--it should be right around 13 ohms.

--DD